* [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand
@ 2020-06-02 19:49 Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
` (31 more replies)
0 siblings, 32 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
recordmcount has its own ELF wrapper code and could utilize
objtool's ELF code to more-portably handle architecture variations.
This series makes recordmcount a subcommand of objtool. It very
gradually convert recordmcount to become a subcommand of objtool and
then reuses parts of objtool's ELF code. recordmcount maps the file in
and collects simple information it needs to append a section to the
object file. The only part of the original file it modifies is the
address of new section tables -- interestingly enough this
resembles RCU in that we don't really trim the old tables so
much as unlink them via a critical offset and then rely on
future tooling, in this case, to drop the unused bits. Much of
the recordmcount ELF code is only reading and walking the data
structures to collect the mcount locations it records in a separate
area of memory. This means it's safe to mix access to the mapped
file with access to the objtool-style linked data
structures as we gradually convert it to using only the linked data
structures. Once the old ELF code is no longer in use we can drop it
and use objtool to take over the task of writing the results without
using the RCU-like trick any more.
Testing:
I've been using scripts to test cross compilation and execution of
objtool, and mcount on objects built for x86, ppc64le, arm64, s390, and
sparc. I used PowerPC as a sample arch for fixing a bug (see Changes)
and confirmed it builds a full zImage with defconfig
(CONFIG_DYNAMIC_FTRACE=y).
Changes
v4:
Split out recordmcount cleanups and upstreamed.
[ https://lore.kernel.org/lkml/20190802134712.2d8cc63f@gandalf.local.home/ ]
Split out and iterated on objtool multi-arch support.
[ https://lore.kernel.org/lkml/cover.1586468801.git.mhelsley@vmware.com/ ]
Split out expanded relocation support, renamed types, and functions
to reflect expanded relocation support, and posted.
[ https://lore.kernel.org/lkml/cover.1590785960.git.mhelsley@vmware.com/ ]
This set is based on the patches sent upstream and posted above.
Adapted to renames by Ingo and Peter: s/elf_open/elf_open_read/
Added weak symbols for mcount subcommand
This nicely eliminated the need for the mcount.h header.
Added tools/objtool/Makefile per-arch SUBCMD_ blocks for each
arch recordmcount / mcount supports.
Moved ftrace/mcount/record.h from objtool_dep to recordmcount_dep
This keeps the dependencies better organized.
Fixed Makefile issue reported for PowerPC and a couple other archs
by kbuild test robot. The always-$(BUILD_C_RECORDMCOUNT)
line wasn't sufficiently replaced. Added to prepare-objtool
target in top level Makefile.
Split up dependencies to be independent of CONFIG_STACK_VALIDATION
and CONFIG_UNWINDER_ORC since these are x86-specific.
Now any arch which uses the C version of recordmcount
will build objtool if dynamic tracing is enabled.
Added a second rename at the end to be consistent with other
objtool subcommands.
v3:
Rebased on mainline. s/elf_open/elf_read/ in recordmcount.c
v2:
Fix whitespace before line continuation
Add ftrace/mcount/record.h to objtool_dep
Rename the Makefile variable BUILD_C_RECORDMCOUNT to
better reflect its purpose
Similar: rename recordmcount_source => recordmcount_dep
When using objtool we can just depend on the
binary rather than the source the binary is
built from. This should address Josh's feedback and
make the Makefile code a bit clearer
Add a comment to make reading the Makefile a little
easier
Rebased to latest mainline -rc
Matt Helsley (32):
objtool: Prepare to merge recordmcount
objtool: Make recordmcount into mcount subcmd
objtool: recordmcount: Start using objtool's elf wrapper
objtool: recordmcount: Search for __mcount_loc before walking the
sections
objtool: recordmcount: Convert do_func() relhdrs
objtool: mcount: Remove unused fname parameter
objtool: mcount: Use libelf for section header names
objtool: mcount: Walk objtool Elf structs in find_secsym_ndx
objtool: mcount: Use symbol structs to find mcount relocations
objtool: mcount: Walk relocation lists
objtool: mcount: Move get_mcountsym
objtool: mcount: Replace MIPS offset types
objtool: mcount: Move is_fake_mcount()
objtool: mcount: Stop using ehdr in find_section_sym_index
objtool: mcount: Move find_section_sym_index()
objtool: mcount: Restrict using ehdr in append_func()
objtool: mcount: Use objtool ELF to write
objtool: mcount: Move nop_mcount()
objtool: mcount: Move has_rel_mcount() and tot_relsize()
objtool: mcount: Move relocation entry size detection
objtool: mcount: Only keep ELF file size
objtool: mcount: Use ELF header from objtool
objtool: mcount: Remove unused file mapping
objtool: mcount: Reduce usage of _size wrapper
objtool: mcount: Move mcount_adjust out of wrapper
objtool: mcount: Pre-allocate new ELF sections
objtool: mcount: Generic location and relocation table types
objtool: mcount: Move sift_rel_mcount out of wrapper file
objtool: mcount: Remove wrapper for ELF relocation type
objtool: mcount: Remove wrapper double-include trick
objtool: mcount: Remove endian wrappers
objtool: mcount: Rename
Documentation/dontdiff | 2 +-
Documentation/trace/ftrace-design.rst | 4 +-
Documentation/trace/ftrace.rst | 6 +-
Makefile | 24 +-
arch/arm64/include/asm/ftrace.h | 2 +-
arch/x86/include/asm/ftrace.h | 2 +-
kernel/trace/Kconfig | 2 +-
scripts/.gitignore | 1 -
scripts/Makefile | 1 -
scripts/Makefile.build | 22 +-
scripts/recordmcount.c | 663 --------------------
scripts/recordmcount.h | 606 ------------------
scripts/sorttable.h | 2 +-
tools/objtool/.gitignore | 1 +
tools/objtool/Build | 2 +
tools/objtool/Makefile | 37 +-
tools/objtool/builtin-mcount.c | 50 ++
tools/objtool/builtin.h | 2 +
tools/objtool/elf.c | 5 +-
tools/objtool/elf.h | 2 +
tools/objtool/mcount.c | 682 +++++++++++++++++++++
tools/objtool/objtool.c | 1 +
tools/objtool/objtool.h | 1 +
{scripts => tools/objtool}/recordmcount.pl | 0
tools/objtool/weak.c | 5 +
25 files changed, 821 insertions(+), 1304 deletions(-)
delete mode 100644 scripts/recordmcount.c
delete mode 100644 scripts/recordmcount.h
create mode 100644 tools/objtool/builtin-mcount.c
create mode 100644 tools/objtool/mcount.c
rename {scripts => tools/objtool}/recordmcount.pl (100%)
base-commit: 2160e6958fc4fa0a70d5f8a2f32760c7ab3bfd6c
--
2.20.1
^ permalink raw reply [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-09 8:54 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
` (30 subsequent siblings)
31 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Move recordmcount into the objtool directory. We keep this step separate
so changes which turn recordmcount into a subcommand of objtool don't
get obscured.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
Documentation/trace/ftrace-design.rst | 4 ++--
Documentation/trace/ftrace.rst | 2 +-
Makefile | 15 +++++++++------
scripts/.gitignore | 1 -
scripts/Makefile | 1 -
scripts/Makefile.build | 11 ++++++-----
tools/objtool/.gitignore | 1 +
tools/objtool/Build | 2 ++
tools/objtool/Makefile | 13 ++++++++++++-
{scripts => tools/objtool}/recordmcount.c | 0
{scripts => tools/objtool}/recordmcount.h | 0
{scripts => tools/objtool}/recordmcount.pl | 0
12 files changed, 33 insertions(+), 17 deletions(-)
rename {scripts => tools/objtool}/recordmcount.c (100%)
rename {scripts => tools/objtool}/recordmcount.h (100%)
rename {scripts => tools/objtool}/recordmcount.pl (100%)
diff --git a/Documentation/trace/ftrace-design.rst b/Documentation/trace/ftrace-design.rst
index a8e22e0db63c..dea8db5e79d0 100644
--- a/Documentation/trace/ftrace-design.rst
+++ b/Documentation/trace/ftrace-design.rst
@@ -261,7 +261,7 @@ You need very few things to get the syscalls tracing in an arch.
HAVE_FTRACE_MCOUNT_RECORD
-------------------------
-See scripts/recordmcount.pl for more info. Just fill in the arch-specific
+See tools/objtool/recordmcount.pl for more info. Just fill in the arch-specific
details for how to locate the addresses of mcount call sites via objdump.
This option doesn't make much sense without also implementing dynamic ftrace.
@@ -379,7 +379,7 @@ linux/ftrace.h for the functions::
ftrace_make_call()
The rec->ip value is the address of the mcount call site that was collected
-by the scripts/recordmcount.pl during build time.
+by the tools/objtool/recordmcount.pl during build time.
The last function is used to do runtime patching of the active tracer. This
will be modifying the assembly code at the location of the ftrace_call symbol
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index 3b5614b1d1a5..9adefcc3c7a8 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -2685,7 +2685,7 @@ starts of pointing to a simple return. (Enabling FTRACE will
include the -pg switch in the compiling of the kernel.)
At compile time every C file object is run through the
-recordmcount program (located in the scripts directory). This
+recordmcount program (located in the tools/objtool directory). This
program will parse the ELF headers in the C object to find all
the locations in the .text section that call mcount. Starting
with gcc version 4.6, the -mfentry has been added for x86, which
diff --git a/Makefile b/Makefile
index 04f5662ae61a..d353a0a65a71 100644
--- a/Makefile
+++ b/Makefile
@@ -844,6 +844,7 @@ ifdef CONFIG_DYNAMIC_FTRACE
ifdef CONFIG_HAVE_C_RECORDMCOUNT
BUILD_C_RECORDMCOUNT := y
export BUILD_C_RECORDMCOUNT
+ objtool_target := tools/objtool FORCE
endif
endif
endif
@@ -1023,10 +1024,10 @@ endif
export mod_sign_cmd
HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+has_libelf := $(call try-run,\
+ echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
ifdef CONFIG_STACK_VALIDATION
- has_libelf := $(call try-run,\
- echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
ifeq ($(has_libelf),1)
objtool_target := tools/objtool FORCE
else
@@ -1163,13 +1164,15 @@ uapi-asm-generic:
PHONY += prepare-objtool
prepare-objtool: $(objtool_target)
-ifeq ($(SKIP_STACK_VALIDATION),1)
-ifdef CONFIG_UNWINDER_ORC
+ifneq ($(has_libelf),1)
+ ifdef CONFIG_UNWINDER_ORC
@echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
-else
+ else
+ ifeq ($(SKIP_STACK_VALIDATION),1)
@echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
-endif
+ endif
+ endif
endif
# Generate some files
diff --git a/scripts/.gitignore b/scripts/.gitignore
index 0d1c8e217cd7..dafda6d2c306 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -2,7 +2,6 @@
bin2c
kallsyms
unifdef
-recordmcount
sorttable
asn1_compiler
extract-cert
diff --git a/scripts/Makefile b/scripts/Makefile
index 95ecf970c74c..d8d81de4f1cb 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -5,7 +5,6 @@
always-$(CONFIG_BUILD_BIN2C) += bin2c
always-$(CONFIG_KALLSYMS) += kallsyms
-always-$(BUILD_C_RECORDMCOUNT) += recordmcount
always-$(CONFIG_BUILDTIME_TABLE_SORT) += sorttable
always-$(CONFIG_ASN1) += asn1_compiler
always-$(CONFIG_MODULE_SIG_FORMAT) += sign-file
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9fcbfac15d1d..d753facdb943 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -174,18 +174,19 @@ endif
# files, including recordmcount.
sub_cmd_record_mcount = \
if [ $(@) != "scripts/mod/empty.o" ]; then \
- $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
+ $(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
fi;
-recordmcount_source := $(srctree)/scripts/recordmcount.c \
- $(srctree)/scripts/recordmcount.h
+
+recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
+ $(srctree)/tools/objtool/recordmcount.h
else
-sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
"$(if $(CONFIG_64BIT),64,32)" \
"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
"$(if $(part-of-module),1,0)" "$(@)";
-recordmcount_source := $(srctree)/scripts/recordmcount.pl
+recordmcount_source := $(srctree)/tools/objtool/recordmcount.pl
endif # BUILD_C_RECORDMCOUNT
cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
$(sub_cmd_record_mcount))
diff --git a/tools/objtool/.gitignore b/tools/objtool/.gitignore
index 45cefda24c7b..ea441abcd1d3 100644
--- a/tools/objtool/.gitignore
+++ b/tools/objtool/.gitignore
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
arch/x86/lib/inat-tables.c
objtool
+recordmcount
fixdep
diff --git a/tools/objtool/Build b/tools/objtool/Build
index b7222d5cc7bc..4d399aff76de 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -35,3 +35,5 @@ $(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
$(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
$(call rule_mkdir)
$(call if_changed_dep,cc_o_c)
+
+recordmcount-y += recordmcount.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 7770edcda3a0..285474a77fe9 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -31,6 +31,12 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
LIBELF_LIBS := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+RECORDMCOUNT := $(OUTPUT)recordmcount
+RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
+ifeq ($(BUILD_C_RECORDMCOUNT),y)
+all: $(RECORDMCOUNT)
+endif
+
all: $(OBJTOOL)
INCLUDES := -I$(srctree)/tools/include \
@@ -63,15 +69,20 @@ $(OBJTOOL_IN): fixdep FORCE
@$(CONFIG_SHELL) ./sync-check.sh
@$(MAKE) $(build)=objtool
+$(RECORDMCOUNT_IN): fixdep FORCE
+ @$(MAKE) $(build)=recordmcount
+
$(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
+$(RECORDMCOUNT): $(RECORDMCOUNT_IN)
+ $(QUIET_LINK)$(CC) $(RECORDMCOUNT_IN) $(KBUILD_HOSTLDFLAGS) -o $@
$(LIBSUBCMD): fixdep FORCE
$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
clean:
- $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
+ $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) $(RECORDMCOUNT)
$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
$(Q)$(RM) $(OUTPUT)arch/x86/inat-tables.c $(OUTPUT)fixdep
diff --git a/scripts/recordmcount.c b/tools/objtool/recordmcount.c
similarity index 100%
rename from scripts/recordmcount.c
rename to tools/objtool/recordmcount.c
diff --git a/scripts/recordmcount.h b/tools/objtool/recordmcount.h
similarity index 100%
rename from scripts/recordmcount.h
rename to tools/objtool/recordmcount.h
diff --git a/scripts/recordmcount.pl b/tools/objtool/recordmcount.pl
similarity index 100%
rename from scripts/recordmcount.pl
rename to tools/objtool/recordmcount.pl
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-09 9:00 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
` (29 subsequent siblings)
31 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than a standalone executable merge recordmcount as a sub command
of objtool. This is a small step towards cleaning up recordmcount and
eventually sharing ELF code with objtool.
For the initial step all that's required is a bit of Makefile changes
and invoking the former main() function from recordmcount.c because the
subcommand code uses similar function arguments as main when dispatching.
objtool ignores some object files that tracing does not, specifically
those with OBJECT_FILES_NON_STANDARD Makefile variables. For this reason
we keep the recordmcount_dep separate from the objtool_dep. When using
objtool mcount we can also, like the other objtool invocations, just
depend on the binary rather than the source the binary is built from.
Subsequent patches will gradually convert recordmcount to use
more and more of libelf/objtool's ELF accessor code. This will both
clean up recordmcount to be more easily readable and remove
recordmcount's crude accessor wrapping code.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
Documentation/dontdiff | 2 +-
Documentation/trace/ftrace.rst | 6 ++--
Makefile | 9 ++++--
arch/arm64/include/asm/ftrace.h | 2 +-
arch/x86/include/asm/ftrace.h | 2 +-
kernel/trace/Kconfig | 2 +-
scripts/Makefile.build | 19 +++++++------
scripts/sorttable.h | 2 +-
tools/objtool/Build | 4 +--
tools/objtool/Makefile | 48 +++++++++++++++++++++++--------
tools/objtool/builtin-mcount.c | 50 +++++++++++++++++++++++++++++++++
tools/objtool/builtin.h | 2 ++
tools/objtool/objtool.c | 1 +
tools/objtool/objtool.h | 1 +
tools/objtool/recordmcount.c | 36 +++++++-----------------
tools/objtool/weak.c | 5 ++++
16 files changed, 131 insertions(+), 60 deletions(-)
create mode 100644 tools/objtool/builtin-mcount.c
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index 72fc2e9e2b63..d7e0ec691e02 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -211,7 +211,7 @@ r420_reg_safe.h
r600_reg_safe.h
randomize_layout_hash.h
randomize_layout_seed.h
-recordmcount
+objtool
relocs
rlim_names.h
rn50_reg_safe.h
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index 9adefcc3c7a8..6b9fc7cad543 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -2684,8 +2684,8 @@ every kernel function, produced by the -pg switch in gcc),
starts of pointing to a simple return. (Enabling FTRACE will
include the -pg switch in the compiling of the kernel.)
-At compile time every C file object is run through the
-recordmcount program (located in the tools/objtool directory). This
+At compile time every C file object is run through objtool's
+mcount subcommand (located in the tools/objtool directory). This
program will parse the ELF headers in the C object to find all
the locations in the .text section that call mcount. Starting
with gcc version 4.6, the -mfentry has been added for x86, which
@@ -2699,7 +2699,7 @@ can be traced.
A section called "__mcount_loc" is created that holds
references to all the mcount/fentry call sites in the .text section.
-The recordmcount program re-links this section back into the
+Running "objtool mcount" re-links this section back into the
original object. The final linking stage of the kernel will add all these
references into a single table.
diff --git a/Makefile b/Makefile
index d353a0a65a71..99a4d8c61bdb 100644
--- a/Makefile
+++ b/Makefile
@@ -842,12 +842,12 @@ KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
KBUILD_AFLAGS += $(CC_FLAGS_USING)
ifdef CONFIG_DYNAMIC_FTRACE
ifdef CONFIG_HAVE_C_RECORDMCOUNT
- BUILD_C_RECORDMCOUNT := y
- export BUILD_C_RECORDMCOUNT
+ USE_OBJTOOL_MCOUNT := y
+ export USE_OBJTOOL_MCOUNT
objtool_target := tools/objtool FORCE
endif
endif
-endif
+endif # CONFIG_FUNCTION_TRACER
# We trigger additional mismatches with less inlining
ifdef CONFIG_DEBUG_SECTION_MISMATCH
@@ -1168,6 +1168,9 @@ ifneq ($(has_libelf),1)
ifdef CONFIG_UNWINDER_ORC
@echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
@false
+ else ifdef USE_OBJTOOL_MCOUNT
+ @echo "error: Cannot generate tracing metadata for CONFIG_DYNAMIC_FTRACE, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
+ @false
else
ifeq ($(SKIP_STACK_VALIDATION),1)
@echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 91fa4baa1a93..5fd71bf592d5 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -62,7 +62,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
return addr + AARCH64_INSN_SIZE;
/*
* addr is the address of the mcount call instruction.
- * recordmcount does the necessary offset calculation.
+ * "objtool mcount" does the necessary offset calculation.
*/
return addr;
}
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 84b9449be080..c849f3818369 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -23,7 +23,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
/*
* addr is the address of the mcount call instruction.
- * recordmcount does the necessary offset calculation.
+ * "objtool mcount" does the necessary offset calculation.
*/
return addr;
}
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 743647005f64..ae74647b06fa 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -59,7 +59,7 @@ config HAVE_NOP_MCOUNT
config HAVE_C_RECORDMCOUNT
bool
help
- C version of recordmcount available?
+ C version of objtool mcount available?
config TRACER_MAX_TRACE
bool
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d753facdb943..ab0aa6088039 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -163,22 +163,23 @@ endif
ifdef CONFIG_FTRACE_MCOUNT_RECORD
ifndef CC_USING_RECORD_MCOUNT
-# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
-ifdef BUILD_C_RECORDMCOUNT
+# The compiler does not support generation of the __mcount_loc section.
+# Generate it manually with "objtool mcount record" or recordmcount.pl
+ifdef USE_OBJTOOL_MCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
RECORDMCOUNT_FLAGS = -w
endif
# Due to recursion, we must skip empty.o.
# The empty.o file is created in the make process in order to determine
# the target endianness and word size. It is made before all other C
-# files, including recordmcount.
+# files, including objtool.
sub_cmd_record_mcount = \
if [ $(@) != "scripts/mod/empty.o" ]; then \
- $(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
+ $(objtree)/tools/objtool/objtool mcount record $(RECORDMCOUNT_FLAGS) "$(@)"; \
fi;
-recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
- $(srctree)/tools/objtool/recordmcount.h
+recordmcount_dep = $(objtree)/tools/objtool/objtool \
+ $(wildcard include/config/ftrace/mcount/record.h)
else
sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
@@ -186,8 +187,8 @@ sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)"
"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
"$(if $(part-of-module),1,0)" "$(@)";
-recordmcount_source := $(srctree)/tools/objtool/recordmcount.pl
-endif # BUILD_C_RECORDMCOUNT
+recordmcount_dep = $(srctree)/tools/objtool/recordmcount.pl
+endif # USE_OBJTOOL_MCOUNT
cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
$(sub_cmd_record_mcount))
endif # CC_USING_RECORD_MCOUNT
@@ -263,7 +264,7 @@ cmd_undef_syms = echo
endif
# Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_dep) $(objtool_dep) FORCE
$(call cmd,force_checksrc)
$(call if_changed_rule,cc_o_c)
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index a2baa2fefb13..986aa3414cf6 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -11,7 +11,7 @@
* Some of code was taken out of arch/x86/kernel/unwind_orc.c, written by:
* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
*
- * Some of this code was taken out of recordmcount.h written by:
+ * Some of this code was taken out of objtool mcount written by:
*
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
diff --git a/tools/objtool/Build b/tools/objtool/Build
index 4d399aff76de..f4f0515d4f91 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -7,9 +7,11 @@ objtool-$(SUBCMD_CHECK) += special.o
objtool-$(SUBCMD_ORC) += check.o
objtool-$(SUBCMD_ORC) += orc_gen.o
objtool-$(SUBCMD_ORC) += orc_dump.o
+objtool-$(SUBCMD_MCOUNT) += recordmcount.o
objtool-y += builtin-check.o
objtool-y += builtin-orc.o
+objtool-y += builtin-mcount.o
objtool-y += elf.o
objtool-y += objtool.o
@@ -35,5 +37,3 @@ $(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
$(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
$(call rule_mkdir)
$(call if_changed_dep,cc_o_c)
-
-recordmcount-y += recordmcount.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 285474a77fe9..ffef73f7f47e 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -31,12 +31,6 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
LIBELF_LIBS := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
-RECORDMCOUNT := $(OUTPUT)recordmcount
-RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
-ifeq ($(BUILD_C_RECORDMCOUNT),y)
-all: $(RECORDMCOUNT)
-endif
-
all: $(OBJTOOL)
INCLUDES := -I$(srctree)/tools/include \
@@ -55,13 +49,47 @@ AWK = awk
SUBCMD_CHECK := n
SUBCMD_ORC := n
+SUBCMD_MCOUNT := n
ifeq ($(SRCARCH),x86)
SUBCMD_CHECK := y
SUBCMD_ORC := y
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),arm)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),arm64)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),ia64)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),mips)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),powerpc)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),s390)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),sh)
+ SUBCMD_MCOUNT := y
+endif
+
+ifeq ($(SRCARCH),sparc)
+ SUBCMD_MCOUNT := y
endif
-export SUBCMD_CHECK SUBCMD_ORC
+export SUBCMD_CHECK SUBCMD_ORC SUBCMD_MCOUNT
export srctree OUTPUT CFLAGS SRCARCH AWK
include $(srctree)/tools/build/Makefile.include
@@ -69,20 +97,16 @@ $(OBJTOOL_IN): fixdep FORCE
@$(CONFIG_SHELL) ./sync-check.sh
@$(MAKE) $(build)=objtool
-$(RECORDMCOUNT_IN): fixdep FORCE
- @$(MAKE) $(build)=recordmcount
$(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
-$(RECORDMCOUNT): $(RECORDMCOUNT_IN)
- $(QUIET_LINK)$(CC) $(RECORDMCOUNT_IN) $(KBUILD_HOSTLDFLAGS) -o $@
$(LIBSUBCMD): fixdep FORCE
$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
clean:
- $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) $(RECORDMCOUNT)
+ $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
$(Q)$(RM) $(OUTPUT)arch/x86/inat-tables.c $(OUTPUT)fixdep
diff --git a/tools/objtool/builtin-mcount.c b/tools/objtool/builtin-mcount.c
new file mode 100644
index 000000000000..4ffc105ab7bb
--- /dev/null
+++ b/tools/objtool/builtin-mcount.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * objtool mcount:
+ *
+ * This command analyzes a .o file and constructs a table of the locations of
+ * calls to 'mcount' useful to ftrace. We can optionally append this table to
+ * the object file ("objtool mcount record foo.o") or output it separately
+ * ("objtool mcount show"). The latter can be used to compare the expected
+ * callers of mcount to those actually found.
+ */
+
+#include <string.h>
+#include <subcmd/parse-options.h>
+#include "builtin.h"
+#include "objtool.h"
+
+static const char * const mcount_usage[] = {
+ "objtool mcount record [<options>] file.o [file2.o ...]",
+ NULL,
+};
+
+bool warn_on_notrace_sect;
+
+const static struct option mcount_options[] = {
+ OPT_BOOLEAN('w', "warn-on-notrace-section", &warn_on_notrace_sect,
+ "Emit a warning when a section omitting mcount "
+ "(possibly due to \"notrace\" marking) is encountered"),
+ OPT_END(),
+};
+
+int cmd_mcount(int argc, const char **argv)
+{
+ argc--; argv++;
+ if (argc <= 0)
+ usage_with_options(mcount_usage, mcount_options);
+
+ if (!strncmp(argv[0], "record", 6)) {
+ argc = parse_options(argc, argv,
+ mcount_options, mcount_usage, 0);
+ if (argc < 1)
+ usage_with_options(mcount_usage, mcount_options);
+
+ return record_mcount(argc, argv);
+ }
+
+ usage_with_options(mcount_usage, mcount_options);
+
+ return 0;
+}
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
index 85c979caa367..9c7331592fa7 100644
--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -12,5 +12,7 @@ extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);
+extern bool is_cmd_mcount_available(void);
+extern int cmd_mcount(int argc, const char **argv);
#endif /* _BUILTIN_H */
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 58fdda510653..b2d6b9fec7dd 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -35,6 +35,7 @@ static const char objtool_usage_string[] =
static struct cmd_struct objtool_cmds[] = {
{"check", cmd_check, "Perform stack metadata validation on an object file" },
{"orc", cmd_orc, "Generate in-place ORC unwind tables for an object file" },
+ {"mcount", cmd_mcount, "Construct a table of locations of calls to mcount. Useful for ftrace."},
};
bool help;
diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
index 528028a66816..c6563aa9d921 100644
--- a/tools/objtool/objtool.h
+++ b/tools/objtool/objtool.h
@@ -21,6 +21,7 @@ struct objtool_file {
int check(const char *objname, bool orc);
int orc_dump(const char *objname);
+int record_mcount(int argc, const char **argv);
int create_orc(struct objtool_file *file);
int create_orc_sections(struct objtool_file *file);
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 7225107a9aaf..601e83840085 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
- * recordmcount.c: construct a table of the locations of calls to 'mcount'
- * so that ftrace can find them quickly.
+ * Construct a table of the locations of calls to 'mcount' so that ftrace
+ * can find them quickly.
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
*
* Restructured to fit Linux format, as well as other updates:
@@ -24,7 +24,6 @@
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
-#include <getopt.h>
#include <elf.h>
#include <fcntl.h>
#include <stdio.h>
@@ -32,6 +31,8 @@
#include <string.h>
#include <unistd.h>
+#include "objtool.h"
+
#ifndef EM_AARCH64
#define EM_AARCH64 183
#define R_AARCH64_NONE 0
@@ -47,7 +48,7 @@ static int mmap_failed; /* Boolean flag. */
static char gpfx; /* prefix for global symbol name (sometimes '_') */
static struct stat sb; /* Remember .st_size, etc. */
static const char *altmcount; /* alternate mcount symbol name */
-static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
+extern int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
static void *file_map; /* pointer of the mapped file */
static void *file_end; /* pointer to the end of the mapped file */
static int file_updated; /* flag to state file was changed */
@@ -488,7 +489,7 @@ static int do_file(char const *const fname)
goto out;
case ELFDATA2LSB:
if (*(unsigned char const *)&endian != 1) {
- /* main() is big endian, file.o is little endian. */
+ /* objtool is big endian, file.o is little endian. */
w = w4rev;
w2 = w2rev;
w8 = w8rev;
@@ -501,7 +502,7 @@ static int do_file(char const *const fname)
break;
case ELFDATA2MSB:
if (*(unsigned char const *)&endian != 0) {
- /* main() is little endian, file.o is big endian. */
+ /* objtool is little endian, file.o is big endian. */
w = w4rev;
w2 = w2rev;
w8 = w8rev;
@@ -615,33 +616,16 @@ static int do_file(char const *const fname)
return rc;
}
-int main(int argc, char *argv[])
+int record_mcount(int argc, const char **argv)
{
const char ftrace[] = "/ftrace.o";
int ftrace_size = sizeof(ftrace) - 1;
int n_error = 0; /* gcc-4.3.0 false positive complaint */
- int c;
int i;
- while ((c = getopt(argc, argv, "w")) >= 0) {
- switch (c) {
- case 'w':
- warn_on_notrace_sect = 1;
- break;
- default:
- fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
- return 0;
- }
- }
-
- if ((argc - optind) < 1) {
- fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
- return 0;
- }
-
/* Process each file in turn, allowing deep failure. */
- for (i = optind; i < argc; i++) {
- char *file = argv[i];
+ for (i = 0; i < argc; i++) {
+ const char *file = argv[i];
int len;
/*
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
index 942ea5e8ac36..0c9161bb1612 100644
--- a/tools/objtool/weak.c
+++ b/tools/objtool/weak.c
@@ -29,6 +29,11 @@ int __weak orc_dump(const char *_objname)
UNSUPPORTED("orc");
}
+int __weak record_mcount(int argc, const char **argv)
+{
+ UNSUPPORTED("mcount");
+}
+
int __weak create_orc(struct objtool_file *file)
{
UNSUPPORTED("orc");
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
` (28 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Use struct elf to grab the file descriptor. We will later
move these calls into other functions as we expand the
lifetime of the struct elf so that it can be passed to
objtool elf.[ch] functions.
This creates the libelf/objtool data structures and gives
us two separate ways to walk the ELF file -- the libelf/objtool
way and the old recordmcount wrapper way which avoids these
extra data structures by using indices, offsets, and pointers
into the mmapped ELF file.
Subsequent patches will convert from the old recordmcount
accessors to the libelf/objtool accessors.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 601e83840085..b2c606eb269b 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -33,6 +33,8 @@
#include "objtool.h"
+#include "elf.h"
+
#ifndef EM_AARCH64
#define EM_AARCH64 183
#define R_AARCH64_NONE 0
@@ -57,6 +59,8 @@ static void *file_ptr; /* current file pointer location */
static void *file_append; /* added to the end of the file */
static size_t file_append_size; /* how much is added to end of file */
+static struct elf *lf;
+
/* Per-file resource cleanup when multiple files. */
static void file_append_cleanup(void)
{
@@ -73,6 +77,9 @@ static void mmap_cleanup(void)
else
free(file_map);
file_map = NULL;
+ if (lf)
+ elf_close(lf);
+ lf = NULL;
}
/* ulseek, uwrite, ...: Check return value for errors. */
@@ -170,11 +177,12 @@ static void *mmap_file(char const *fname)
file_updated = 0;
sb.st_size = 0;
- fd_map = open(fname, O_RDONLY);
- if (fd_map < 0) {
+ lf = elf_open_read(fname, O_RDONLY);
+ if (!lf) {
perror(fname);
return NULL;
}
+ fd_map = lf->fd;
if (fstat(fd_map, &sb) < 0) {
perror(fname);
goto out;
@@ -194,14 +202,14 @@ static void *mmap_file(char const *fname)
}
if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
perror(fname);
- free(file_map);
- file_map = NULL;
+ mmap_cleanup();
goto out;
}
} else
mmap_failed = 0;
out:
- close(fd_map);
+ elf_close(lf);
+ lf = NULL;
fd_map = -1;
file_end = file_map + sb.st_size;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (2 preceding siblings ...)
2020-06-02 19:49 ` [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
` (27 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
recordmcount iterates over the sections in the order they're
listed in the ELF file and checks whether the section name
indicates it's of interest. Objtool's elf code works differently
-- it scans the elf file and builds up data structures
representing the headers, sections, etc. and then supplies
functions to search these structures. Both walk the elf file
in order, however objtool uses more memory to enable faster
searches it needs for other tools such as the reliable backtrace
support offered by the ORC unwinder.
Rather than walk the section table a second time in the recordmcount
code, we use objtool's elf code to search for the section
recordmcount is interested in. This also simplifies flow and means
we can easily check for already-processed object files before we
do any of the more complex things recordmcount does.
This also allows us to remove the already_has_rel_mcount string
pointer trick.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 4 ----
tools/objtool/recordmcount.h | 17 +++--------------
2 files changed, 3 insertions(+), 18 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index b2c606eb269b..f585bf7f45f5 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -208,8 +208,6 @@ static void *mmap_file(char const *fname)
} else
mmap_failed = 0;
out:
- elf_close(lf);
- lf = NULL;
fd_map = -1;
file_end = file_map + sb.st_size;
@@ -424,8 +422,6 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static char const *already_has_rel_mcount = "success"; /* our work here is done! */
-
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 74eab03e31d4..1a848b8104c8 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -473,11 +473,6 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
char const *const txtname = &shstrtab[w(txthdr->sh_name)];
- if (strcmp("__mcount_loc", txtname) == 0) {
- fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
- fname);
- return already_has_rel_mcount;
- }
if (w(txthdr->sh_type) != SHT_PROGBITS ||
!(_w(txthdr->sh_flags) & SHF_EXECINSTR))
return NULL;
@@ -506,10 +501,6 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
for (; nhdr; --nhdr, ++shdrp) {
txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
- if (txtname == already_has_rel_mcount) {
- totrelsz = 0;
- break;
- }
if (txtname && is_mcounted_section_name(txtname))
totrelsz += _w(shdrp->sh_size);
}
@@ -545,6 +536,9 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
int result = 0;
+ if (find_section_by_name(lf, "__mcount_loc") != NULL)
+ return 0;
+
totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
if (totrelsz == 0)
return 0;
@@ -564,11 +558,6 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
char const *const txtname = has_rel_mcount(relhdr, shdr0,
shstrtab, fname);
- if (txtname == already_has_rel_mcount) {
- result = 0;
- file_updated = 0;
- goto out; /* Nothing to be done; don't append! */
- }
if (txtname && is_mcounted_section_name(txtname)) {
unsigned int recsym;
uint_t recval = 0;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (3 preceding siblings ...)
2020-06-02 19:49 ` [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter Matt Helsley
` (26 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Use objtool's ELF data structures to visit the relocation
sections in the top-level ELF file walking function, do_func().
This means we can pass pointers to the relocation header structures
into nested functions and avoid the indexing patterns for them.
These conversions don't use libelf/objtool to modify the ELF
file -- it only changes the way we walk the ELF sections and do
lookups to find the relocations.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 62 +++++++++++++++++++-----------------
1 file changed, 32 insertions(+), 30 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 1a848b8104c8..3c4807dca3d0 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -285,7 +285,7 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
return mcountsym;
}
-static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
+static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
Elf_Ehdr const *const ehdr,
Elf_Sym const **sym0,
char const **str0,
@@ -293,10 +293,10 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- unsigned const symsec_sh_link = w(relhdr->sh_link);
+ unsigned const symsec_sh_link = relhdr->sh_link;
Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
- Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
+ Elf_Rel const *const rel0 = (Elf_Rel const *)(relhdr->sh_offset
+ (void *)ehdr);
*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
@@ -316,9 +316,9 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
static uint_t *sift_rel_mcount(uint_t *mlocp,
unsigned const offbase,
Elf_Rel **const mrelpp,
- Elf_Shdr const *const relhdr,
+ GElf_Shdr const *const relhdr,
Elf_Ehdr const *const ehdr,
- unsigned const recsym,
+ unsigned const recsym_index,
uint_t const recval,
unsigned const reltype)
{
@@ -327,8 +327,8 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- unsigned rel_entsize = _w(relhdr->sh_entsize);
- unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+ unsigned int rel_entsize = relhdr->sh_entsize;
+ unsigned const nrel = relhdr->sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
@@ -344,7 +344,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
_w(_w(relp->r_offset) - recval + mcount_adjust);
mrelp->r_offset = _w(offbase
+ ((void *)mlocp - (void *)mloc0));
- Elf_r_info(mrelp, recsym, reltype);
+ Elf_r_info(mrelp, recsym_index, reltype);
if (rel_entsize == sizeof(Elf_Rela)) {
((Elf_Rela *)mrelp)->r_addend = addend;
*mlocp++ = 0;
@@ -364,7 +364,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
* that are not going to be traced. The mcount calls here will be converted
* into nops.
*/
-static int nop_mcount(Elf_Shdr const *const relhdr,
+static int nop_mcount(GElf_Shdr const *const relhdr,
Elf_Ehdr const *const ehdr,
const char *const txtname)
{
@@ -373,9 +373,9 @@ static int nop_mcount(Elf_Shdr const *const relhdr,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
- unsigned rel_entsize = _w(relhdr->sh_entsize);
- unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+ Elf_Shdr const *const shdr = &shdr0[relhdr->sh_info];
+ unsigned int rel_entsize = relhdr->sh_entsize;
+ unsigned const nrel = relhdr->sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
int once = 0;
@@ -464,13 +464,13 @@ static int find_secsym_ndx(unsigned const txtndx,
}
/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
-static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
+static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */
Elf_Shdr const *const shdr0,
char const *const shstrtab,
char const *const fname)
{
/* .sh_info depends on .sh_type == SHT_REL[,A] */
- Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
+ Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info];
char const *const txtname = &shstrtab[w(txthdr->sh_name)];
if (w(txthdr->sh_type) != SHT_PROGBITS ||
@@ -479,30 +479,29 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
return txtname;
}
-static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
+static char const *has_rel_mcount(GElf_Shdr const *const relhdr,
Elf_Shdr const *const shdr0,
char const *const shstrtab,
char const *const fname)
{
- if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
+ if (relhdr->sh_type != SHT_REL && relhdr->sh_type != SHT_RELA)
return NULL;
return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
}
static unsigned tot_relsize(Elf_Shdr const *const shdr0,
- unsigned nhdr,
const char *const shstrtab,
const char *const fname)
{
+ struct section *sec;
unsigned totrelsz = 0;
- Elf_Shdr const *shdrp = shdr0;
char const *txtname;
- for (; nhdr; --nhdr, ++shdrp) {
- txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
+ list_for_each_entry(sec, &lf->sections, list) {
+ txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab, fname);
if (txtname && is_mcounted_section_name(txtname))
- totrelsz += _w(shdrp->sh_size);
+ totrelsz += sec->sh.sh_size;
}
return totrelsz;
}
@@ -514,13 +513,11 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- unsigned const nhdr = w2(ehdr->e_shnum);
Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
+ (void *)ehdr);
- Elf_Shdr const *relhdr;
- unsigned k;
+ GElf_Shdr const *relhdr;
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -534,12 +531,14 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
unsigned rel_entsize = 0;
unsigned symsec_sh_link = 0;
+ struct section *sec;
+
int result = 0;
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
- totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
+ totrelsz = tot_relsize(shdr0, shstrtab, fname);
if (totrelsz == 0)
return 0;
mrel0 = umalloc(totrelsz);
@@ -555,22 +554,25 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
return -1;
}
- for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
- char const *const txtname = has_rel_mcount(relhdr, shdr0,
+ list_for_each_entry(sec, &lf->sections, list) {
+ char const *txtname;
+
+ relhdr = &sec->sh;
+ txtname = has_rel_mcount(relhdr, shdr0,
shstrtab, fname);
if (txtname && is_mcounted_section_name(txtname)) {
unsigned int recsym;
uint_t recval = 0;
- symsec_sh_link = w(relhdr->sh_link);
- result = find_secsym_ndx(w(relhdr->sh_info), txtname,
+ symsec_sh_link = relhdr->sh_link;
+ result = find_secsym_ndx(relhdr->sh_info, txtname,
&recval, &recsym,
&shdr0[symsec_sh_link],
ehdr);
if (result)
goto out;
- rel_entsize = _w(relhdr->sh_entsize);
+ rel_entsize = relhdr->sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
relhdr, ehdr, recsym, recval, reltype);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (4 preceding siblings ...)
2020-06-02 19:49 ` [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
@ 2020-06-02 19:49 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names Matt Helsley
` (25 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:49 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The name of the object file being processed is unused in
the wrapper's leaf functions so we no longer need to pass
it as a parameter.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 4 ++--
tools/objtool/recordmcount.h | 19 ++++++++-----------
2 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index f585bf7f45f5..9941683b3f60 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -586,7 +586,7 @@ static int do_file(char const *const fname)
reltype = R_MIPS_32;
is_fake_mcount32 = MIPS32_is_fake_mcount;
}
- if (do32(ehdr, fname, reltype) < 0)
+ if (do32(ehdr, reltype) < 0)
goto out;
break;
case ELFCLASS64: {
@@ -607,7 +607,7 @@ static int do_file(char const *const fname)
Elf64_r_info = MIPS64_r_info;
is_fake_mcount64 = MIPS64_is_fake_mcount;
}
- if (do64(ghdr, fname, reltype) < 0)
+ if (do64(ghdr, reltype) < 0)
goto out;
break;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 3c4807dca3d0..3250a461895d 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -466,8 +466,7 @@ static int find_secsym_ndx(unsigned const txtndx,
/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */
Elf_Shdr const *const shdr0,
- char const *const shstrtab,
- char const *const fname)
+ char const *const shstrtab)
{
/* .sh_info depends on .sh_type == SHT_REL[,A] */
Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info];
@@ -481,25 +480,23 @@ static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype *
static char const *has_rel_mcount(GElf_Shdr const *const relhdr,
Elf_Shdr const *const shdr0,
- char const *const shstrtab,
- char const *const fname)
+ char const *const shstrtab)
{
if (relhdr->sh_type != SHT_REL && relhdr->sh_type != SHT_RELA)
return NULL;
- return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
+ return __has_rel_mcount(relhdr, shdr0, shstrtab);
}
static unsigned tot_relsize(Elf_Shdr const *const shdr0,
- const char *const shstrtab,
- const char *const fname)
+ const char *const shstrtab)
{
struct section *sec;
unsigned totrelsz = 0;
char const *txtname;
list_for_each_entry(sec, &lf->sections, list) {
- txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab, fname);
+ txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab);
if (txtname && is_mcounted_section_name(txtname))
totrelsz += sec->sh.sh_size;
}
@@ -508,7 +505,7 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
/* Overall supervision for Elf32 ET_REL file. */
-static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
+static int do_func(Elf_Ehdr *const ehdr,
unsigned const reltype)
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
@@ -538,7 +535,7 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
- totrelsz = tot_relsize(shdr0, shstrtab, fname);
+ totrelsz = tot_relsize(shdr0, shstrtab);
if (totrelsz == 0)
return 0;
mrel0 = umalloc(totrelsz);
@@ -559,7 +556,7 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
relhdr = &sec->sh;
txtname = has_rel_mcount(relhdr, shdr0,
- shstrtab, fname);
+ shstrtab);
if (txtname && is_mcounted_section_name(txtname)) {
unsigned int recsym;
uint_t recval = 0;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (5 preceding siblings ...)
2020-06-02 19:49 ` [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
` (24 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than passing in the string table contents as a parameter,
pass in the section index of the string table and rely on libelf
string table accessor functions to look up section names.
Note that modifying the string table with libelf will come later
so append_func() is unchanged.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/elf.c | 3 +-
tools/objtool/elf.h | 1 +
tools/objtool/recordmcount.c | 2 +-
tools/objtool/recordmcount.h | 89 ++++++++++++++----------------------
4 files changed, 37 insertions(+), 58 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 067e2850a116..2e8f5f90e264 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -138,8 +138,7 @@ struct section *find_section_by_name(const struct elf *elf, const char *name)
return NULL;
}
-static struct section *find_section_by_index(struct elf *elf,
- unsigned int idx)
+struct section *find_section_by_index(const struct elf *elf, unsigned int idx)
{
struct section *sec;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 78a2db23b8b6..ae82479a8259 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -125,6 +125,7 @@ int elf_write(const struct elf *elf);
void elf_close(struct elf *elf);
struct section *find_section_by_name(const struct elf *elf, const char *name);
+struct section *find_section_by_index(const struct elf *elf, unsigned int idx);
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 9941683b3f60..f20582ac99e2 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -177,7 +177,7 @@ static void *mmap_file(char const *fname)
file_updated = 0;
sb.st_size = 0;
- lf = elf_open_read(fname, O_RDONLY);
+ lf = elf_open_read(fname, O_RDWR);
if (!lf) {
perror(fname);
return NULL;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 3250a461895d..b487308992ce 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -25,7 +25,6 @@
#undef sift_rel_mcount
#undef nop_mcount
#undef find_secsym_ndx
-#undef __has_rel_mcount
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
@@ -55,7 +54,6 @@
# define sift_rel_mcount sift64_rel_mcount
# define nop_mcount nop_mcount_64
# define find_secsym_ndx find64_secsym_ndx
-# define __has_rel_mcount __has64_rel_mcount
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_64
@@ -88,7 +86,6 @@
# define sift_rel_mcount sift32_rel_mcount
# define nop_mcount nop_mcount_32
# define find_secsym_ndx find32_secsym_ndx
-# define __has_rel_mcount __has32_rel_mcount
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_32
@@ -197,6 +194,7 @@ static int append_func(Elf_Ehdr *const ehdr,
shstr->sh_size = _w(t);
shstr->sh_offset = _w(sb.st_size);
+
t += sb.st_size;
t += (_align & -t); /* word-byte align */
new_e_shoff = t;
@@ -260,7 +258,7 @@ static int append_func(Elf_Ehdr *const ehdr,
return -1;
if (uwrite(ehdr, sizeof(*ehdr)) < 0)
return -1;
- return 0;
+ return elf_write(lf);
}
static unsigned get_mcountsym(Elf_Sym const *const sym0,
@@ -285,7 +283,7 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
return mcountsym;
}
-static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
+static void get_sym_str_and_relp(const struct section * const rels,
Elf_Ehdr const *const ehdr,
Elf_Sym const **sym0,
char const **str0,
@@ -293,10 +291,10 @@ static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- unsigned const symsec_sh_link = relhdr->sh_link;
+ unsigned const symsec_sh_link = rels->sh.sh_link;
Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
- Elf_Rel const *const rel0 = (Elf_Rel const *)(relhdr->sh_offset
+ Elf_Rel const *const rel0 = (Elf_Rel const *)(rels->sh.sh_offset
+ (void *)ehdr);
*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
@@ -316,7 +314,7 @@ static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
static uint_t *sift_rel_mcount(uint_t *mlocp,
unsigned const offbase,
Elf_Rel **const mrelpp,
- GElf_Shdr const *const relhdr,
+ const struct section * const rels,
Elf_Ehdr const *const ehdr,
unsigned const recsym_index,
uint_t const recval,
@@ -327,12 +325,12 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- unsigned int rel_entsize = relhdr->sh_entsize;
- unsigned const nrel = relhdr->sh_size / rel_entsize;
+ unsigned int rel_entsize = rels->sh.sh_entsize;
+ unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
- get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+ get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
for (t = nrel; t; --t) {
if (!mcountsym)
@@ -364,7 +362,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
* that are not going to be traced. The mcount calls here will be converted
* into nops.
*/
-static int nop_mcount(GElf_Shdr const *const relhdr,
+static int nop_mcount(const struct section * const rels,
Elf_Ehdr const *const ehdr,
const char *const txtname)
{
@@ -373,14 +371,14 @@ static int nop_mcount(GElf_Shdr const *const relhdr,
Elf_Sym const *sym0;
char const *str0;
Elf_Rel const *relp;
- Elf_Shdr const *const shdr = &shdr0[relhdr->sh_info];
- unsigned int rel_entsize = relhdr->sh_entsize;
- unsigned const nrel = relhdr->sh_size / rel_entsize;
+ Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
+ unsigned rel_entsize = rels->sh.sh_entsize;
+ unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
int once = 0;
- get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+ get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
for (t = nrel; t; --t) {
int ret = -1;
@@ -463,40 +461,27 @@ static int find_secsym_ndx(unsigned const txtndx,
return -1;
}
-/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
-static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */
- Elf_Shdr const *const shdr0,
- char const *const shstrtab)
+static char const *has_rel_mcount(const struct section * const rels)
{
- /* .sh_info depends on .sh_type == SHT_REL[,A] */
- Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info];
- char const *const txtname = &shstrtab[w(txthdr->sh_name)];
-
- if (w(txthdr->sh_type) != SHT_PROGBITS ||
- !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
+ const struct section *txts;
+ if (rels->sh.sh_type != SHT_REL && rels->sh.sh_type != SHT_RELA)
return NULL;
- return txtname;
-}
-
-static char const *has_rel_mcount(GElf_Shdr const *const relhdr,
- Elf_Shdr const *const shdr0,
- char const *const shstrtab)
-{
- if (relhdr->sh_type != SHT_REL && relhdr->sh_type != SHT_RELA)
+ txts = find_section_by_index(lf, rels->sh.sh_info);
+ if ((txts->sh.sh_type != SHT_PROGBITS) ||
+ !(txts->sh.sh_flags & SHF_EXECINSTR))
return NULL;
- return __has_rel_mcount(relhdr, shdr0, shstrtab);
+ return txts->name;
}
-static unsigned tot_relsize(Elf_Shdr const *const shdr0,
- const char *const shstrtab)
+static unsigned tot_relsize(void)
{
- struct section *sec;
+ const struct section *sec;
unsigned totrelsz = 0;
char const *txtname;
list_for_each_entry(sec, &lf->sections, list) {
- txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab);
+ txtname = has_rel_mcount(sec);
if (txtname && is_mcounted_section_name(txtname))
totrelsz += sec->sh.sh_size;
}
@@ -510,11 +495,6 @@ static int do_func(Elf_Ehdr *const ehdr,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
- char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
- + (void *)ehdr);
-
- GElf_Shdr const *relhdr;
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -528,14 +508,14 @@ static int do_func(Elf_Ehdr *const ehdr,
unsigned rel_entsize = 0;
unsigned symsec_sh_link = 0;
- struct section *sec;
+ const struct section *sec;
int result = 0;
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
- totrelsz = tot_relsize(shdr0, shstrtab);
+ totrelsz = tot_relsize();
if (totrelsz == 0)
return 0;
mrel0 = umalloc(totrelsz);
@@ -554,38 +534,37 @@ static int do_func(Elf_Ehdr *const ehdr,
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
- relhdr = &sec->sh;
- txtname = has_rel_mcount(relhdr, shdr0,
- shstrtab);
+ txtname = has_rel_mcount(sec);
if (txtname && is_mcounted_section_name(txtname)) {
unsigned int recsym;
uint_t recval = 0;
- symsec_sh_link = relhdr->sh_link;
- result = find_secsym_ndx(relhdr->sh_info, txtname,
+ symsec_sh_link = sec->sh.sh_link;
+ result = find_secsym_ndx(sec->sh.sh_info, txtname,
&recval, &recsym,
&shdr0[symsec_sh_link],
ehdr);
if (result)
goto out;
- rel_entsize = relhdr->sh_entsize;
+ rel_entsize = sec->sh.sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
- relhdr, ehdr, recsym, recval, reltype);
+ sec, ehdr, recsym, recval, reltype);
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
/*
* This section is ignored by ftrace, but still
* has mcount calls. Convert them to nops now.
*/
- if (nop_mcount(relhdr, ehdr, txtname) < 0) {
+ if (nop_mcount(sec, ehdr, txtname) < 0) {
result = -1;
goto out;
}
}
}
if (!result && mloc0 != mlocp)
- result = append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
+ result = append_func(ehdr, &shdr0[w2(ehdr->e_shstrndx)],
+ mloc0, mlocp, mrel0, mrelp,
rel_entsize, symsec_sh_link);
out:
free(mrel0);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (6 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
` (23 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than using indices into raw ELF32/64 tables mapped for the
wrapper, use the objtool functions to find the a suitable symbol
in the given text section.
Also take advantage of this commit to rename the function to
something that reads more easily.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 2 ++
tools/objtool/recordmcount.h | 42 ++++++++++++++++--------------------
2 files changed, 21 insertions(+), 23 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index f20582ac99e2..843027a46e1b 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -422,6 +422,8 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
+static const unsigned int missing_sym = (unsigned int)-1;
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index b487308992ce..dba1c385106f 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -24,7 +24,7 @@
#undef mcount_adjust
#undef sift_rel_mcount
#undef nop_mcount
-#undef find_secsym_ndx
+#undef find_section_sym_index
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
@@ -53,7 +53,7 @@
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
# define nop_mcount nop_mcount_64
-# define find_secsym_ndx find64_secsym_ndx
+# define find_section_sym_index find64_section_sym_index
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_64
@@ -85,7 +85,7 @@
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
# define nop_mcount nop_mcount_32
-# define find_secsym_ndx find32_secsym_ndx
+# define find_section_sym_index find32_section_sym_index
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define get_sym_str_and_relp get_sym_str_and_relp_32
@@ -427,38 +427,36 @@ static int nop_mcount(const struct section * const rels,
* Num: Value Size Type Bind Vis Ndx Name
* 2: 00000000 0 SECTION LOCAL DEFAULT 1
*/
-static int find_secsym_ndx(unsigned const txtndx,
+static int find_section_sym_index(unsigned const txtndx,
char const *const txtname,
uint_t *const recvalp,
unsigned int *sym_index,
- Elf_Shdr const *const symhdr,
Elf_Ehdr const *const ehdr)
{
- Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
- + (void *)ehdr);
- unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
- Elf_Sym const *symp;
- unsigned t;
+ struct symbol *sym;
+ struct section *txts = find_section_by_index(lf, txtndx);
- for (symp = sym0, t = nsym; t; --t, ++symp) {
- unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
+ if (!txts) {
+ fprintf(stderr, "Cannot find section %u: %s.\n",
+ txtndx, txtname);
+ return missing_sym;
+ }
- if (txtndx == w2(symp->st_shndx)
- /* avoid STB_WEAK */
- && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
+ list_for_each_entry(sym, &txts->symbol_list, list) {
+ if ((sym->bind == STB_LOCAL) || (sym->bind == STB_GLOBAL)) {
/* function symbols on ARM have quirks, avoid them */
if (w2(ehdr->e_machine) == EM_ARM
- && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
+ && sym->type == STT_FUNC)
continue;
- *recvalp = _w(symp->st_value);
- *sym_index = symp - sym0;
+ *recvalp = sym->sym.st_value;
+ *sym_index = sym->idx;
return 0;
}
}
fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
txtndx, txtname);
- return -1;
+ return missing_sym;
}
static char const *has_rel_mcount(const struct section * const rels)
@@ -540,10 +538,8 @@ static int do_func(Elf_Ehdr *const ehdr,
uint_t recval = 0;
symsec_sh_link = sec->sh.sh_link;
- result = find_secsym_ndx(sec->sh.sh_info, txtname,
- &recval, &recsym,
- &shdr0[symsec_sh_link],
- ehdr);
+ result = find_section_sym_index(sec->sh.sh_info,
+ txtname, &recval, &recsym, ehdr);
if (result)
goto out;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (7 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists Matt Helsley
` (22 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than open coding symbol name lookups in get_sym_and_*()
we rename the structure and use objtool's lookup function to
get the symbol name for a relocation. We also change the name
of the function to better reflect its purpose.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/elf.c | 2 +-
tools/objtool/elf.h | 1 +
tools/objtool/recordmcount.h | 54 ++++++++++--------------------------
3 files changed, 17 insertions(+), 40 deletions(-)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 2e8f5f90e264..107f89660e45 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -149,7 +149,7 @@ struct section *find_section_by_index(const struct elf *elf, unsigned int idx)
return NULL;
}
-static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
+struct symbol *find_symbol_by_index(const struct elf *elf, unsigned int idx)
{
struct symbol *sym;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index ae82479a8259..235719730392 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -129,6 +129,7 @@ struct section *find_section_by_index(const struct elf *elf, unsigned int idx);
struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
+struct symbol *find_symbol_by_index(const struct elf *elf, unsigned int idx);
struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index dba1c385106f..d49da1e32315 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -28,7 +28,7 @@
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
-#undef get_sym_str_and_relp
+#undef get_relp
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
@@ -56,7 +56,7 @@
# define find_section_sym_index find64_section_sym_index
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
-# define get_sym_str_and_relp get_sym_str_and_relp_64
+# define get_relp get_relp_64
# define do_func do64
# define get_mcountsym get_mcountsym_64
# define is_fake_mcount is_fake_mcount64
@@ -88,7 +88,7 @@
# define find_section_sym_index find32_section_sym_index
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
-# define get_sym_str_and_relp get_sym_str_and_relp_32
+# define get_relp get_relp_32
# define do_func do32
# define get_mcountsym get_mcountsym_32
# define is_fake_mcount is_fake_mcount32
@@ -261,15 +261,10 @@ static int append_func(Elf_Ehdr *const ehdr,
return elf_write(lf);
}
-static unsigned get_mcountsym(Elf_Sym const *const sym0,
- Elf_Rel const *relp,
- char const *const str0)
+static unsigned get_mcountsym(Elf_Rel const *relp)
{
- unsigned mcountsym = 0;
-
- Elf_Sym const *const symp =
- &sym0[Elf_r_sym(relp)];
- char const *symname = &str0[w(symp->st_name)];
+ struct symbol *sym = find_symbol_by_index(lf, Elf_r_sym(relp));
+ char const *symname = sym->name;
char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
char const *fentry = "__fentry__";
@@ -278,31 +273,16 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
if (strcmp(mcount, symname) == 0 ||
(altmcount && strcmp(altmcount, symname) == 0) ||
(strcmp(fentry, symname) == 0))
- mcountsym = Elf_r_sym(relp);
-
- return mcountsym;
+ return Elf_r_sym(relp);
+ return 0;
}
-static void get_sym_str_and_relp(const struct section * const rels,
- Elf_Ehdr const *const ehdr,
- Elf_Sym const **sym0,
- char const **str0,
- Elf_Rel const **relp)
+static void get_relp(const struct section * const rels,
+ Elf_Ehdr const *const ehdr,
+ Elf_Rel const **relp)
{
- Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
- + (void *)ehdr);
- unsigned const symsec_sh_link = rels->sh.sh_link;
- Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
- Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
Elf_Rel const *const rel0 = (Elf_Rel const *)(rels->sh.sh_offset
+ (void *)ehdr);
-
- *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
- + (void *)ehdr);
-
- *str0 = (char const *)(_w(strsec->sh_offset)
- + (void *)ehdr);
-
*relp = rel0;
}
@@ -322,19 +302,17 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
{
uint_t *const mloc0 = mlocp;
Elf_Rel *mrelp = *mrelpp;
- Elf_Sym const *sym0;
- char const *str0;
Elf_Rel const *relp;
unsigned int rel_entsize = rels->sh.sh_entsize;
unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
unsigned t;
- get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
+ get_relp(rels, ehdr, &relp);
for (t = nrel; t; --t) {
if (!mcountsym)
- mcountsym = get_mcountsym(sym0, relp, str0);
+ mcountsym = get_mcountsym(relp);
if (mcountsym && mcountsym == Elf_r_sym(relp) &&
!is_fake_mcount(relp)) {
@@ -368,8 +346,6 @@ static int nop_mcount(const struct section * const rels,
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf_Sym const *sym0;
- char const *str0;
Elf_Rel const *relp;
Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
unsigned rel_entsize = rels->sh.sh_entsize;
@@ -378,13 +354,13 @@ static int nop_mcount(const struct section * const rels,
unsigned t;
int once = 0;
- get_sym_str_and_relp(rels, ehdr, &sym0, &str0, &relp);
+ get_relp(rels, ehdr, &relp);
for (t = nrel; t; --t) {
int ret = -1;
if (!mcountsym)
- mcountsym = get_mcountsym(sym0, relp, str0);
+ mcountsym = get_mcountsym(relp);
if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
if (make_nop)
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (8 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym Matt Helsley
` (21 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than walk the section tables using the old recordmcount mapping
of the ELF file, walk the section list provided by objtool's ELF code.
This removes the last use of of the Elf_r_sym wrapper so we remove
that too.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 10 +---
tools/objtool/recordmcount.h | 103 +++++++++--------------------------
2 files changed, 28 insertions(+), 85 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 843027a46e1b..dafa6dd10d04 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -429,9 +429,9 @@ static const unsigned int missing_sym = (unsigned int)-1;
#define RECORD_MCOUNT_64
#include "recordmcount.h"
-static int arm_is_fake_mcount(Elf32_Rel const *rp)
+static int arm_is_fake_mcount(struct reloc const *rp)
{
- switch (ELF32_R_TYPE(w(rp->r_info))) {
+ switch (rp->type) {
case R_ARM_THM_CALL:
case R_ARM_CALL:
case R_ARM_PC24:
@@ -462,11 +462,6 @@ union mips_r_info {
} r_mips;
};
-static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
-{
- return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
-}
-
static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
{
rp->r_info = ((union mips_r_info){
@@ -605,7 +600,6 @@ static int do_file(char const *const fname)
}
if (w2(ghdr->e_machine) == EM_MIPS) {
reltype = R_MIPS_64;
- Elf64_r_sym = MIPS64_r_sym;
Elf64_r_info = MIPS64_r_info;
is_fake_mcount64 = MIPS64_is_fake_mcount;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index d49da1e32315..cbf66b63ff82 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -28,21 +28,14 @@
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
-#undef get_relp
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
-#undef Elf_Sym
-#undef ELF_R_SYM
-#undef Elf_r_sym
#undef ELF_R_INFO
#undef Elf_r_info
-#undef ELF_ST_BIND
-#undef ELF_ST_TYPE
-#undef fn_ELF_R_SYM
#undef fn_ELF_R_INFO
#undef uint_t
#undef _w
@@ -56,7 +49,6 @@
# define find_section_sym_index find64_section_sym_index
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
-# define get_relp get_relp_64
# define do_func do64
# define get_mcountsym get_mcountsym_64
# define is_fake_mcount is_fake_mcount64
@@ -68,14 +60,8 @@
# define Elf_Shdr Elf64_Shdr
# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
-# define Elf_Sym Elf64_Sym
-# define ELF_R_SYM ELF64_R_SYM
-# define Elf_r_sym Elf64_r_sym
# define ELF_R_INFO ELF64_R_INFO
# define Elf_r_info Elf64_r_info
-# define ELF_ST_BIND ELF64_ST_BIND
-# define ELF_ST_TYPE ELF64_ST_TYPE
-# define fn_ELF_R_SYM fn_ELF64_R_SYM
# define fn_ELF_R_INFO fn_ELF64_R_INFO
# define uint_t uint64_t
# define _w w8
@@ -88,7 +74,6 @@
# define find_section_sym_index find32_section_sym_index
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
-# define get_relp get_relp_32
# define do_func do32
# define get_mcountsym get_mcountsym_32
# define is_fake_mcount is_fake_mcount32
@@ -100,14 +85,8 @@
# define Elf_Shdr Elf32_Shdr
# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
-# define Elf_Sym Elf32_Sym
-# define ELF_R_SYM ELF32_R_SYM
-# define Elf_r_sym Elf32_r_sym
# define ELF_R_INFO ELF32_R_INFO
# define Elf_r_info Elf32_r_info
-# define ELF_ST_BIND ELF32_ST_BIND
-# define ELF_ST_TYPE ELF32_ST_TYPE
-# define fn_ELF_R_SYM fn_ELF32_R_SYM
# define fn_ELF_R_INFO fn_ELF32_R_INFO
# define uint_t uint32_t
# define _w w
@@ -116,17 +95,11 @@
#endif
/* Functions and pointers that do_file() may override for specific e_machine. */
-static int fn_is_fake_mcount(Elf_Rel const *rp)
+static int fn_is_fake_mcount(struct reloc const *reloc)
{
return 0;
}
-static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
-
-static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
-{
- return ELF_R_SYM(_w(rp->r_info));
-}
-static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
+static int (*is_fake_mcount)(struct reloc const *reloc) = fn_is_fake_mcount;
static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
{
@@ -157,10 +130,10 @@ static int mcount_adjust = 0;
*/
#define MIPS_FAKEMCOUNT_OFFSET 4
-static int MIPS_is_fake_mcount(Elf_Rel const *rp)
+static int MIPS_is_fake_mcount(struct reloc const *reloc)
{
static Elf_Addr old_r_offset = ~(Elf_Addr)0;
- Elf_Addr current_r_offset = _w(rp->r_offset);
+ Elf_Addr current_r_offset = reloc->offset;
int is_fake;
is_fake = (old_r_offset != ~(Elf_Addr)0) &&
@@ -261,9 +234,9 @@ static int append_func(Elf_Ehdr *const ehdr,
return elf_write(lf);
}
-static unsigned get_mcountsym(Elf_Rel const *relp)
+static unsigned get_mcountsym(struct reloc *reloc)
{
- struct symbol *sym = find_symbol_by_index(lf, Elf_r_sym(relp));
+ struct symbol *sym = reloc->sym;
char const *symname = sym->name;
char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
char const *fentry = "__fentry__";
@@ -273,19 +246,10 @@ static unsigned get_mcountsym(Elf_Rel const *relp)
if (strcmp(mcount, symname) == 0 ||
(altmcount && strcmp(altmcount, symname) == 0) ||
(strcmp(fentry, symname) == 0))
- return Elf_r_sym(relp);
+ return GELF_R_INFO(reloc->sym->idx, reloc->type);
return 0;
}
-static void get_relp(const struct section * const rels,
- Elf_Ehdr const *const ehdr,
- Elf_Rel const **relp)
-{
- Elf_Rel const *const rel0 = (Elf_Rel const *)(rels->sh.sh_offset
- + (void *)ehdr);
- *relp = rel0;
-}
-
/*
* Look at the relocations in order to find the calls to mcount.
* Accumulate the section offsets that are found, and their relocation info,
@@ -295,29 +259,23 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
unsigned const offbase,
Elf_Rel **const mrelpp,
const struct section * const rels,
- Elf_Ehdr const *const ehdr,
unsigned const recsym_index,
uint_t const recval,
unsigned const reltype)
{
uint_t *const mloc0 = mlocp;
Elf_Rel *mrelp = *mrelpp;
- Elf_Rel const *relp;
unsigned int rel_entsize = rels->sh.sh_entsize;
- unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
- unsigned t;
-
- get_relp(rels, ehdr, &relp);
+ struct reloc *reloc;
- for (t = nrel; t; --t) {
+ list_for_each_entry(reloc, &rels->reloc_list, list) {
if (!mcountsym)
- mcountsym = get_mcountsym(relp);
+ mcountsym = get_mcountsym(reloc);
- if (mcountsym && mcountsym == Elf_r_sym(relp) &&
- !is_fake_mcount(relp)) {
+ if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
uint_t const addend =
- _w(_w(relp->r_offset) - recval + mcount_adjust);
+ _w(reloc->offset - recval + mcount_adjust);
mrelp->r_offset = _w(offbase
+ ((void *)mlocp - (void *)mloc0));
Elf_r_info(mrelp, recsym_index, reltype);
@@ -329,7 +287,6 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
}
- relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
}
*mrelpp = mrelp;
return mlocp;
@@ -340,31 +297,29 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
* that are not going to be traced. The mcount calls here will be converted
* into nops.
*/
-static int nop_mcount(const struct section * const rels,
+static int nop_mcount(struct section * const rels,
Elf_Ehdr const *const ehdr,
const char *const txtname)
{
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ (void *)ehdr);
- Elf_Rel const *relp;
+ struct reloc *reloc;
Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
- unsigned rel_entsize = rels->sh.sh_entsize;
- unsigned const nrel = rels->sh.sh_size / rel_entsize;
unsigned mcountsym = 0;
- unsigned t;
int once = 0;
- get_relp(rels, ehdr, &relp);
-
- for (t = nrel; t; --t) {
+ list_for_each_entry(reloc, &rels->reloc_list, list) {
int ret = -1;
if (!mcountsym)
- mcountsym = get_mcountsym(relp);
+ mcountsym = get_mcountsym(reloc);
- if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
- if (make_nop)
- ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
+ if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
+ if (make_nop) {
+ ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + reloc->offset);
+ if (ret < 0)
+ return -1;
+ }
if (warn_on_notrace_sect && !once) {
printf("Section %s has mcount callers being ignored\n",
txtname);
@@ -380,15 +335,9 @@ static int nop_mcount(const struct section * const rels,
* as a nop (don't do anything with it).
*/
if (!ret) {
- Elf_Rel rel;
- rel = *(Elf_Rel *)relp;
- Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
- if (ulseek((void *)relp - (void *)ehdr, SEEK_SET) < 0)
- return -1;
- if (uwrite(&rel, sizeof(rel)) < 0)
- return -1;
+ reloc->type = rel_type_nop;
+ rels->changed = true;
}
- relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
}
return 0;
}
@@ -482,7 +431,7 @@ static int do_func(Elf_Ehdr *const ehdr,
unsigned rel_entsize = 0;
unsigned symsec_sh_link = 0;
- const struct section *sec;
+ struct section *sec;
int result = 0;
@@ -522,7 +471,7 @@ static int do_func(Elf_Ehdr *const ehdr,
rel_entsize = sec->sh.sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
- sec, ehdr, recsym, recval, reltype);
+ sec, recsym, recval, reltype);
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
/*
* This section is ignored by ftrace, but still
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (9 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types Matt Helsley
` (20 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Now that it's been stripped of using the old recordmcount ELF
wrapper get_mcountsym() is ready to be promoted out of the
double-included wrapper header.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 16 ++++++++++++++++
tools/objtool/recordmcount.h | 19 -------------------
2 files changed, 16 insertions(+), 19 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index dafa6dd10d04..f72d313a2b51 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -422,6 +422,22 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
+static unsigned get_mcountsym(struct reloc *reloc)
+{
+ struct symbol *sym = reloc->sym;
+ char const *symname = sym->name;
+ char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
+ char const *fentry = "__fentry__";
+
+ if (symname[0] == '.')
+ ++symname; /* ppc64 hack */
+ if (strcmp(mcount, symname) == 0 ||
+ (altmcount && strcmp(altmcount, symname) == 0) ||
+ (strcmp(fentry, symname) == 0))
+ return GELF_R_INFO(reloc->sym->idx, reloc->type);
+ return 0;
+}
+
static const unsigned int missing_sym = (unsigned int)-1;
/* 32 bit and 64 bit are very similar */
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index cbf66b63ff82..a3fb62e88450 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -27,7 +27,6 @@
#undef find_section_sym_index
#undef has_rel_mcount
#undef tot_relsize
-#undef get_mcountsym
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
@@ -50,7 +49,6 @@
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define do_func do64
-# define get_mcountsym get_mcountsym_64
# define is_fake_mcount is_fake_mcount64
# define fn_is_fake_mcount fn_is_fake_mcount64
# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
@@ -75,7 +73,6 @@
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define do_func do32
-# define get_mcountsym get_mcountsym_32
# define is_fake_mcount is_fake_mcount32
# define fn_is_fake_mcount fn_is_fake_mcount32
# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
@@ -234,22 +231,6 @@ static int append_func(Elf_Ehdr *const ehdr,
return elf_write(lf);
}
-static unsigned get_mcountsym(struct reloc *reloc)
-{
- struct symbol *sym = reloc->sym;
- char const *symname = sym->name;
- char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
- char const *fentry = "__fentry__";
-
- if (symname[0] == '.')
- ++symname; /* ppc64 hack */
- if (strcmp(mcount, symname) == 0 ||
- (altmcount && strcmp(altmcount, symname) == 0) ||
- (strcmp(fentry, symname) == 0))
- return GELF_R_INFO(reloc->sym->idx, reloc->type);
- return 0;
-}
-
/*
* Look at the relocations in order to find the calls to mcount.
* Accumulate the section offsets that are found, and their relocation info,
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (10 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount() Matt Helsley
` (19 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Replace MIPS is_fake_mcount code using Elf_Addr with
unsigned long for the offsets. This is consistent with the way
that objtool more generally treats offsets and removes the
last use of the Elf_Addr wrapper.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index a3fb62e88450..1a39f7acac11 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -28,7 +28,6 @@
#undef has_rel_mcount
#undef tot_relsize
#undef do_func
-#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
@@ -53,7 +52,6 @@
# define fn_is_fake_mcount fn_is_fake_mcount64
# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
# define mcount_adjust mcount_adjust_64
-# define Elf_Addr Elf64_Addr
# define Elf_Ehdr Elf64_Ehdr
# define Elf_Shdr Elf64_Shdr
# define Elf_Rel Elf64_Rel
@@ -77,7 +75,6 @@
# define fn_is_fake_mcount fn_is_fake_mcount32
# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
# define mcount_adjust mcount_adjust_32
-# define Elf_Addr Elf32_Addr
# define Elf_Ehdr Elf32_Ehdr
# define Elf_Shdr Elf32_Shdr
# define Elf_Rel Elf32_Rel
@@ -129,11 +126,11 @@ static int mcount_adjust = 0;
static int MIPS_is_fake_mcount(struct reloc const *reloc)
{
- static Elf_Addr old_r_offset = ~(Elf_Addr)0;
- Elf_Addr current_r_offset = reloc->offset;
+ static unsigned long old_r_offset = ~0UL;
+ unsigned long current_r_offset = reloc->offset;
int is_fake;
- is_fake = (old_r_offset != ~(Elf_Addr)0) &&
+ is_fake = (old_r_offset != ~0UL) &&
(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
old_r_offset = current_r_offset;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount()
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (11 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
` (18 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Promote the now-bit-independent is_fake_mcount() out of the old
recordmcount ELF wrapper.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 48 +++++++++++++++++++++++++++++++---
tools/objtool/recordmcount.h | 50 ------------------------------------
2 files changed, 45 insertions(+), 53 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index f72d313a2b51..24090f36d26d 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -438,6 +438,48 @@ static unsigned get_mcountsym(struct reloc *reloc)
return 0;
}
+/*
+ * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
+ * _mcount symbol is needed for dynamic function tracer, with it, to disable
+ * tracing(ftrace_make_nop), the instruction in the position is replaced with
+ * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
+ * instruction back. So, here, we set the 2nd one as fake and filter it.
+ *
+ * c: 3c030000 lui v1,0x0 <--> b label
+ * c: R_MIPS_HI16 _mcount
+ * c: R_MIPS_NONE *ABS*
+ * c: R_MIPS_NONE *ABS*
+ * 10: 64630000 daddiu v1,v1,0
+ * 10: R_MIPS_LO16 _mcount
+ * 10: R_MIPS_NONE *ABS*
+ * 10: R_MIPS_NONE *ABS*
+ * 14: 03e0082d move at,ra
+ * 18: 0060f809 jalr v1
+ * label:
+ */
+#define MIPS_FAKEMCOUNT_OFFSET 4
+
+static int MIPS_is_fake_mcount(struct reloc const *reloc)
+{
+ static unsigned long old_r_offset = ~0UL;
+ unsigned long current_r_offset = reloc->offset;
+ int is_fake;
+
+ is_fake = (old_r_offset != ~0UL) &&
+ (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
+ old_r_offset = current_r_offset;
+
+ return is_fake;
+}
+
+/* Functions and pointers that do_file() may override for specific e_machine. */
+static int fn_is_fake_mcount(struct reloc const *reloc)
+{
+ return 0;
+}
+
+static int (*is_fake_mcount)(struct reloc const *reloc) = fn_is_fake_mcount;
+
static const unsigned int missing_sym = (unsigned int)-1;
/* 32 bit and 64 bit are very similar */
@@ -557,7 +599,7 @@ static int do_file(char const *const fname)
altmcount = "__gnu_mcount_nc";
make_nop = make_nop_arm;
rel_type_nop = R_ARM_NONE;
- is_fake_mcount32 = arm_is_fake_mcount;
+ is_fake_mcount = arm_is_fake_mcount;
gpfx = 0;
break;
case EM_AARCH64:
@@ -597,7 +639,7 @@ static int do_file(char const *const fname)
}
if (w2(ehdr->e_machine) == EM_MIPS) {
reltype = R_MIPS_32;
- is_fake_mcount32 = MIPS32_is_fake_mcount;
+ is_fake_mcount = MIPS_is_fake_mcount;
}
if (do32(ehdr, reltype) < 0)
goto out;
@@ -617,7 +659,7 @@ static int do_file(char const *const fname)
if (w2(ghdr->e_machine) == EM_MIPS) {
reltype = R_MIPS_64;
Elf64_r_info = MIPS64_r_info;
- is_fake_mcount64 = MIPS64_is_fake_mcount;
+ is_fake_mcount = MIPS_is_fake_mcount;
}
if (do64(ghdr, reltype) < 0)
goto out;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 1a39f7acac11..65386938693b 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -18,9 +18,6 @@
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
#undef append_func
-#undef is_fake_mcount
-#undef fn_is_fake_mcount
-#undef MIPS_is_fake_mcount
#undef mcount_adjust
#undef sift_rel_mcount
#undef nop_mcount
@@ -48,9 +45,6 @@
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define do_func do64
-# define is_fake_mcount is_fake_mcount64
-# define fn_is_fake_mcount fn_is_fake_mcount64
-# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
# define mcount_adjust mcount_adjust_64
# define Elf_Ehdr Elf64_Ehdr
# define Elf_Shdr Elf64_Shdr
@@ -71,9 +65,6 @@
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define do_func do32
-# define is_fake_mcount is_fake_mcount32
-# define fn_is_fake_mcount fn_is_fake_mcount32
-# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
# define mcount_adjust mcount_adjust_32
# define Elf_Ehdr Elf32_Ehdr
# define Elf_Shdr Elf32_Shdr
@@ -88,13 +79,6 @@
# define _size 4
#endif
-/* Functions and pointers that do_file() may override for specific e_machine. */
-static int fn_is_fake_mcount(struct reloc const *reloc)
-{
- return 0;
-}
-static int (*is_fake_mcount)(struct reloc const *reloc) = fn_is_fake_mcount;
-
static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
{
rp->r_info = _w(ELF_R_INFO(sym, type));
@@ -103,40 +87,6 @@ static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_E
static int mcount_adjust = 0;
-/*
- * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
- * _mcount symbol is needed for dynamic function tracer, with it, to disable
- * tracing(ftrace_make_nop), the instruction in the position is replaced with
- * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
- * instruction back. So, here, we set the 2nd one as fake and filter it.
- *
- * c: 3c030000 lui v1,0x0 <--> b label
- * c: R_MIPS_HI16 _mcount
- * c: R_MIPS_NONE *ABS*
- * c: R_MIPS_NONE *ABS*
- * 10: 64630000 daddiu v1,v1,0
- * 10: R_MIPS_LO16 _mcount
- * 10: R_MIPS_NONE *ABS*
- * 10: R_MIPS_NONE *ABS*
- * 14: 03e0082d move at,ra
- * 18: 0060f809 jalr v1
- * label:
- */
-#define MIPS_FAKEMCOUNT_OFFSET 4
-
-static int MIPS_is_fake_mcount(struct reloc const *reloc)
-{
- static unsigned long old_r_offset = ~0UL;
- unsigned long current_r_offset = reloc->offset;
- int is_fake;
-
- is_fake = (old_r_offset != ~0UL) &&
- (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
- old_r_offset = current_r_offset;
-
- return is_fake;
-}
-
/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
static int append_func(Elf_Ehdr *const ehdr,
Elf_Shdr *const shstr,
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (12 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount() Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index() Matt Helsley
` (17 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
We can use the objtool GElf_Ehdr structure to access ehdr here.
This makes the function completely independent of the old
recordmcount ELF wrapper. The next step will be to promote it
to the C file.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 65386938693b..c7ce6345089d 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -188,7 +188,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
Elf_Rel **const mrelpp,
const struct section * const rels,
unsigned const recsym_index,
- uint_t const recval,
+ unsigned long const recval,
unsigned const reltype)
{
uint_t *const mloc0 = mlocp;
@@ -282,9 +282,8 @@ static int nop_mcount(struct section * const rels,
*/
static int find_section_sym_index(unsigned const txtndx,
char const *const txtname,
- uint_t *const recvalp,
- unsigned int *sym_index,
- Elf_Ehdr const *const ehdr)
+ unsigned long *const recvalp,
+ unsigned int *sym_index)
{
struct symbol *sym;
struct section *txts = find_section_by_index(lf, txtndx);
@@ -298,7 +297,7 @@ static int find_section_sym_index(unsigned const txtndx,
list_for_each_entry(sym, &txts->symbol_list, list) {
if ((sym->bind == STB_LOCAL) || (sym->bind == STB_GLOBAL)) {
/* function symbols on ARM have quirks, avoid them */
- if (w2(ehdr->e_machine) == EM_ARM
+ if (lf->ehdr.e_machine == EM_ARM
&& sym->type == STT_FUNC)
continue;
@@ -387,12 +386,12 @@ static int do_func(Elf_Ehdr *const ehdr,
txtname = has_rel_mcount(sec);
if (txtname && is_mcounted_section_name(txtname)) {
+ unsigned long recval = 0;
unsigned int recsym;
- uint_t recval = 0;
symsec_sh_link = sec->sh.sh_link;
result = find_section_sym_index(sec->sh.sh_info,
- txtname, &recval, &recsym, ehdr);
+ txtname, &recval, &recsym);
if (result)
goto out;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index()
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (13 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
` (16 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
This function is no longer dependent upon the old recordmcount
ELF wrapper code -- it doesn't use the wrapper's Elf_* types nor
does it call wrapped functions. Move it into the C file.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 41 ++++++++++++++++++++++++++++++++
tools/objtool/recordmcount.h | 46 +-----------------------------------
2 files changed, 42 insertions(+), 45 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 24090f36d26d..6150af8d67ce 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -482,6 +482,47 @@ static int (*is_fake_mcount)(struct reloc const *reloc) = fn_is_fake_mcount;
static const unsigned int missing_sym = (unsigned int)-1;
+/*
+ * Find a symbol in the given section, to be used as the base for relocating
+ * the table of offsets of calls to mcount. A local or global symbol suffices,
+ * but avoid a Weak symbol because it may be overridden; the change in value
+ * would invalidate the relocations of the offsets of the calls to mcount.
+ * Often the found symbol will be the unnamed local symbol generated by
+ * GNU 'as' for the start of each section. For example:
+ * Num: Value Size Type Bind Vis Ndx Name
+ * 2: 00000000 0 SECTION LOCAL DEFAULT 1
+ */
+static int find_section_sym_index(unsigned const txtndx,
+ char const *const txtname,
+ unsigned long *const recvalp,
+ unsigned int *sym_index)
+{
+ struct symbol *sym;
+ struct section *txts = find_section_by_index(lf, txtndx);
+
+ if (!txts) {
+ fprintf(stderr, "Cannot find section %u: %s.\n",
+ txtndx, txtname);
+ return missing_sym;
+ }
+
+ list_for_each_entry(sym, &txts->symbol_list, list) {
+ if ((sym->bind == STB_LOCAL) || (sym->bind == STB_GLOBAL)) {
+ /* function symbols on ARM have quirks, avoid them */
+ if (lf->ehdr.e_machine == EM_ARM
+ && sym->type == STT_FUNC)
+ continue;
+
+ *recvalp = sym->sym.st_value;
+ *sym_index = sym->idx;
+ return 0;
+ }
+ }
+ fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
+ txtndx, txtname);
+ return missing_sym;
+}
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index c7ce6345089d..98cf9eea6074 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -21,7 +21,6 @@
#undef mcount_adjust
#undef sift_rel_mcount
#undef nop_mcount
-#undef find_section_sym_index
#undef has_rel_mcount
#undef tot_relsize
#undef do_func
@@ -41,7 +40,6 @@
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
# define nop_mcount nop_mcount_64
-# define find_section_sym_index find64_section_sym_index
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define do_func do64
@@ -61,7 +59,6 @@
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
# define nop_mcount nop_mcount_32
-# define find_section_sym_index find32_section_sym_index
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define do_func do32
@@ -270,47 +267,6 @@ static int nop_mcount(struct section * const rels,
return 0;
}
-/*
- * Find a symbol in the given section, to be used as the base for relocating
- * the table of offsets of calls to mcount. A local or global symbol suffices,
- * but avoid a Weak symbol because it may be overridden; the change in value
- * would invalidate the relocations of the offsets of the calls to mcount.
- * Often the found symbol will be the unnamed local symbol generated by
- * GNU 'as' for the start of each section. For example:
- * Num: Value Size Type Bind Vis Ndx Name
- * 2: 00000000 0 SECTION LOCAL DEFAULT 1
- */
-static int find_section_sym_index(unsigned const txtndx,
- char const *const txtname,
- unsigned long *const recvalp,
- unsigned int *sym_index)
-{
- struct symbol *sym;
- struct section *txts = find_section_by_index(lf, txtndx);
-
- if (!txts) {
- fprintf(stderr, "Cannot find section %u: %s.\n",
- txtndx, txtname);
- return missing_sym;
- }
-
- list_for_each_entry(sym, &txts->symbol_list, list) {
- if ((sym->bind == STB_LOCAL) || (sym->bind == STB_GLOBAL)) {
- /* function symbols on ARM have quirks, avoid them */
- if (lf->ehdr.e_machine == EM_ARM
- && sym->type == STT_FUNC)
- continue;
-
- *recvalp = sym->sym.st_value;
- *sym_index = sym->idx;
- return 0;
- }
- }
- fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
- txtndx, txtname);
- return missing_sym;
-}
-
static char const *has_rel_mcount(const struct section * const rels)
{
const struct section *txts;
@@ -398,7 +354,7 @@ static int do_func(Elf_Ehdr *const ehdr,
rel_entsize = sec->sh.sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
- sec, recsym, recval, reltype);
+ sec, recsym, (uint_t)recval, reltype);
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
/*
* This section is ignored by ftrace, but still
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func()
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (14 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index() Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write Matt Helsley
` (15 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Use the ehdr parameter to append_func() to write the
ELF file's header but use the objtool ELF header data
as the basis for making changes. The makes it clearer
when we can switch from using the old recordmcount
wrapper to write the ELF file because ehdr will only
be passed on to uwrite() calls and those will get
replaced later.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 98cf9eea6074..7ebc617fb3a6 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -99,8 +99,8 @@ static int append_func(Elf_Ehdr *const ehdr,
char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
? ".rela__mcount_loc"
: ".rel__mcount_loc";
- unsigned const old_shnum = w2(ehdr->e_shnum);
- uint_t const old_shoff = _w(ehdr->e_shoff);
+ unsigned const old_shnum = lf->ehdr.e_shnum;
+ uint_t const old_shoff = lf->ehdr.e_shoff;
uint_t const old_shstr_sh_size = _w(shstr->sh_size);
uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
@@ -167,7 +167,7 @@ static int append_func(Elf_Ehdr *const ehdr,
return -1;
ehdr->e_shoff = _w(new_e_shoff);
- ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum)); /* {.rel,}__mcount_loc */
+ ehdr->e_shnum = w2(2 + lf->ehdr.e_shnum); /* {.rel,}__mcount_loc */
if (ulseek(0, SEEK_SET) < 0)
return -1;
if (uwrite(ehdr, sizeof(*ehdr)) < 0)
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (15 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
` (14 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than modify the pseudo-mapping of the ELF file directly,
which is the recordmcount way of operating, use the objtool
section list and generic ELF functions to modify the ELF file.
This eliminates a bunch of code -- the ulseek() and uwrite()
functions -- because it's used to patch the ELF data. Instead
we rely on objtool's ELF code to handle updating the ELF file.
This means a bunch of the odd bits in append_func() also go
away since they did things like update the ELF header, add
to the section table, and append the new section names to the
string table -- all handled by objtool's ELF code.
One unusual part, with respect to objtool is the way we handle
writing nops. Objtool is not designed to modify the an ELF
text section directly (or at least I could not find and example
to base this work on). So we break layering to access the
"data" of the text section via the section's "data buffer".
This is still cleaner -- we can now pass in the section struct
and offset as separate parameters.
Note that this patch does not move the associated parts out
of the wrapper file. We postpone that cleanup for later so that
it's easier to see the changes to the functions rather than
obscuring them with the move.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 161 ++++-------------------------------
tools/objtool/recordmcount.h | 132 +++++++++-------------------
2 files changed, 55 insertions(+), 238 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 6150af8d67ce..89762908290e 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -52,24 +52,9 @@ static struct stat sb; /* Remember .st_size, etc. */
static const char *altmcount; /* alternate mcount symbol name */
extern int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
static void *file_map; /* pointer of the mapped file */
-static void *file_end; /* pointer to the end of the mapped file */
-static int file_updated; /* flag to state file was changed */
-static void *file_ptr; /* current file pointer location */
-
-static void *file_append; /* added to the end of the file */
-static size_t file_append_size; /* how much is added to end of file */
static struct elf *lf;
-/* Per-file resource cleanup when multiple files. */
-static void file_append_cleanup(void)
-{
- free(file_append);
- file_append = NULL;
- file_append_size = 0;
- file_updated = 0;
-}
-
static void mmap_cleanup(void)
{
if (!mmap_failed)
@@ -82,72 +67,11 @@ static void mmap_cleanup(void)
lf = NULL;
}
-/* ulseek, uwrite, ...: Check return value for errors. */
-
-static off_t ulseek(off_t const offset, int const whence)
-{
- switch (whence) {
- case SEEK_SET:
- file_ptr = file_map + offset;
- break;
- case SEEK_CUR:
- file_ptr += offset;
- break;
- case SEEK_END:
- file_ptr = file_map + (sb.st_size - offset);
- break;
- }
- if (file_ptr < file_map) {
- fprintf(stderr, "lseek: seek before file\n");
- return -1;
- }
- return file_ptr - file_map;
-}
-
-static ssize_t uwrite(void const *const buf, size_t const count)
-{
- size_t cnt = count;
- off_t idx = 0;
-
- file_updated = 1;
-
- if (file_ptr + count >= file_end) {
- off_t aoffset = (file_ptr + count) - file_end;
-
- if (aoffset > file_append_size) {
- file_append = realloc(file_append, aoffset);
- file_append_size = aoffset;
- }
- if (!file_append) {
- perror("write");
- file_append_cleanup();
- mmap_cleanup();
- return -1;
- }
- if (file_ptr < file_end) {
- cnt = file_end - file_ptr;
- } else {
- cnt = 0;
- idx = aoffset - count;
- }
- }
-
- if (cnt)
- memcpy(file_ptr, buf, cnt);
-
- if (cnt < count)
- memcpy(file_append + idx, buf + cnt, count - cnt);
-
- file_ptr += count;
- return count;
-}
-
static void * umalloc(size_t size)
{
void *const addr = malloc(size);
if (addr == 0) {
fprintf(stderr, "malloc failed: %zu bytes\n", size);
- file_append_cleanup();
mmap_cleanup();
return NULL;
}
@@ -173,8 +97,6 @@ static void *mmap_file(char const *fname)
fd_map = -1;
mmap_failed = 1;
file_map = NULL;
- file_ptr = NULL;
- file_updated = 0;
sb.st_size = 0;
lf = elf_open_read(fname, O_RDWR);
@@ -210,8 +132,6 @@ static void *mmap_file(char const *fname)
out:
fd_map = -1;
- file_end = file_map + sb.st_size;
-
return file_map;
}
@@ -222,12 +142,16 @@ static unsigned char *ideal_nop;
static char rel_type_nop;
-static int (*make_nop)(void *map, size_t const offset);
+static int (*make_nop)(struct section *, size_t const offset);
-static int make_nop_x86(void *map, size_t const offset)
+static int make_nop_x86(struct section *txts, size_t const offset)
{
uint32_t *ptr;
unsigned char *op;
+ void *map = txts->data->d_buf;
+
+ if (offset < 1)
+ return -1;
/* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
ptr = map + offset;
@@ -239,10 +163,7 @@ static int make_nop_x86(void *map, size_t const offset)
return -1;
/* convert to nop */
- if (ulseek(offset - 1, SEEK_SET) < 0)
- return -1;
- if (uwrite(ideal_nop, 5) < 0)
- return -1;
+ memcpy(op, ideal_nop, 5);
return 0;
}
@@ -266,12 +187,13 @@ static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe
static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */
static unsigned char *push_bl_mcount_thumb;
-static int make_nop_arm(void *map, size_t const offset)
+static int make_nop_arm(struct section *txts, size_t const offset)
{
char *ptr;
int cnt = 1;
int nop_size;
size_t off = offset;
+ void *map = txts->data->d_buf;
ptr = map + offset;
if (memcmp(ptr, bl_mcount_arm, 4) == 0) {
@@ -290,21 +212,19 @@ static int make_nop_arm(void *map, size_t const offset)
return -1;
/* Convert to nop */
- if (ulseek(off, SEEK_SET) < 0)
- return -1;
-
do {
- if (uwrite(ideal_nop, nop_size) < 0)
- return -1;
+ memcpy(map + off, ideal_nop, nop_size);
+ off += nop_size;
} while (--cnt > 0);
return 0;
}
static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};
-static int make_nop_arm64(void *map, size_t const offset)
+static int make_nop_arm64(struct section *txts, size_t const offset)
{
uint32_t *ptr;
+ void *map = txts->data->d_buf;
ptr = map + offset;
/* bl <_mcount> is 0x94000000 before relocation */
@@ -312,52 +232,7 @@ static int make_nop_arm64(void *map, size_t const offset)
return -1;
/* Convert to nop */
- if (ulseek(offset, SEEK_SET) < 0)
- return -1;
- if (uwrite(ideal_nop, 4) < 0)
- return -1;
- return 0;
-}
-
-static int write_file(const char *fname)
-{
- char tmp_file[strlen(fname) + 4];
- size_t n;
-
- if (!file_updated)
- return 0;
-
- sprintf(tmp_file, "%s.rc", fname);
-
- /*
- * After reading the entire file into memory, delete it
- * and write it back, to prevent weird side effects of modifying
- * an object file in place.
- */
- fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
- if (fd_map < 0) {
- perror(fname);
- return -1;
- }
- n = write(fd_map, file_map, sb.st_size);
- if (n != sb.st_size) {
- perror("write");
- close(fd_map);
- return -1;
- }
- if (file_append_size) {
- n = write(fd_map, file_append, file_append_size);
- if (n != file_append_size) {
- perror("write");
- close(fd_map);
- return -1;
- }
- }
- close(fd_map);
- if (rename(tmp_file, fname) < 0) {
- perror(fname);
- return -1;
- }
+ memcpy(map + offset, ideal_nop, 4);
return 0;
}
@@ -682,8 +557,7 @@ static int do_file(char const *const fname)
reltype = R_MIPS_32;
is_fake_mcount = MIPS_is_fake_mcount;
}
- if (do32(ehdr, reltype) < 0)
- goto out;
+ rc = do32(reltype);
break;
case ELFCLASS64: {
Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
@@ -702,15 +576,12 @@ static int do_file(char const *const fname)
Elf64_r_info = MIPS64_r_info;
is_fake_mcount = MIPS_is_fake_mcount;
}
- if (do64(ghdr, reltype) < 0)
- goto out;
+ rc = do64(reltype);
break;
}
} /* end switch */
- rc = write_file(fname);
out:
- file_append_cleanup();
mmap_cleanup();
return rc;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 7ebc617fb3a6..6754bde0bacc 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -24,7 +24,6 @@
#undef has_rel_mcount
#undef tot_relsize
#undef do_func
-#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
@@ -33,7 +32,6 @@
#undef fn_ELF_R_INFO
#undef uint_t
#undef _w
-#undef _align
#undef _size
#ifdef RECORD_MCOUNT_64
@@ -44,8 +42,6 @@
# define tot_relsize tot64_relsize
# define do_func do64
# define mcount_adjust mcount_adjust_64
-# define Elf_Ehdr Elf64_Ehdr
-# define Elf_Shdr Elf64_Shdr
# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
# define ELF_R_INFO ELF64_R_INFO
@@ -53,7 +49,6 @@
# define fn_ELF_R_INFO fn_ELF64_R_INFO
# define uint_t uint64_t
# define _w w8
-# define _align 7u
# define _size 8
#else
# define append_func append32
@@ -63,8 +58,6 @@
# define tot_relsize tot32_relsize
# define do_func do32
# define mcount_adjust mcount_adjust_32
-# define Elf_Ehdr Elf32_Ehdr
-# define Elf_Shdr Elf32_Shdr
# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
# define ELF_R_INFO ELF32_R_INFO
@@ -72,7 +65,6 @@
# define fn_ELF_R_INFO fn_ELF32_R_INFO
# define uint_t uint32_t
# define _w w
-# define _align 3u
# define _size 4
#endif
@@ -84,10 +76,8 @@ static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_E
static int mcount_adjust = 0;
-/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
-static int append_func(Elf_Ehdr *const ehdr,
- Elf_Shdr *const shstr,
- uint_t const *const mloc0,
+/* Append the new __mcount_loc and its relocations. */
+static int append_func(uint_t const *const mloc0,
uint_t const *const mlocp,
Elf_Rel const *const mrel0,
Elf_Rel const *const mrelp,
@@ -95,83 +85,47 @@ static int append_func(Elf_Ehdr *const ehdr,
unsigned int const symsec_sh_link)
{
/* Begin constructing output file */
- Elf_Shdr mcsec;
+ struct section *sec;
char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
? ".rela__mcount_loc"
: ".rel__mcount_loc";
unsigned const old_shnum = lf->ehdr.e_shnum;
- uint_t const old_shoff = lf->ehdr.e_shoff;
- uint_t const old_shstr_sh_size = _w(shstr->sh_size);
- uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
- uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
- uint_t new_e_shoff;
-
- shstr->sh_size = _w(t);
- shstr->sh_offset = _w(sb.st_size);
-
- t += sb.st_size;
- t += (_align & -t); /* word-byte align */
- new_e_shoff = t;
-
- /* body for new shstrtab */
- if (ulseek(sb.st_size, SEEK_SET) < 0)
- return -1;
- if (uwrite(old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size) < 0)
- return -1;
- if (uwrite(mc_name, 1 + strlen(mc_name)) < 0)
- return -1;
-
- /* old(modified) Elf_Shdr table, word-byte aligned */
- if (ulseek(t, SEEK_SET) < 0)
- return -1;
- t += sizeof(Elf_Shdr) * old_shnum;
- if (uwrite(old_shoff + (void *)ehdr,
- sizeof(Elf_Shdr) * old_shnum) < 0)
- return -1;
-
- /* new sections __mcount_loc and .rel__mcount_loc */
- t += 2*sizeof(mcsec);
- mcsec.sh_name = w((sizeof(Elf_Rela) == rel_entsize) + strlen(".rel")
- + old_shstr_sh_size);
- mcsec.sh_type = w(SHT_PROGBITS);
- mcsec.sh_flags = _w(SHF_ALLOC);
- mcsec.sh_addr = 0;
- mcsec.sh_offset = _w(t);
- mcsec.sh_size = _w((void *)mlocp - (void *)mloc0);
- mcsec.sh_link = 0;
- mcsec.sh_info = 0;
- mcsec.sh_addralign = _w(_size);
- mcsec.sh_entsize = _w(_size);
- if (uwrite(&mcsec, sizeof(mcsec)) < 0)
- return -1;
- mcsec.sh_name = w(old_shstr_sh_size);
- mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
- ? w(SHT_RELA)
- : w(SHT_REL);
- mcsec.sh_flags = 0;
- mcsec.sh_addr = 0;
- mcsec.sh_offset = _w((void *)mlocp - (void *)mloc0 + t);
- mcsec.sh_size = _w((void *)mrelp - (void *)mrel0);
- mcsec.sh_link = w(symsec_sh_link);
- mcsec.sh_info = w(old_shnum);
- mcsec.sh_addralign = _w(_size);
- mcsec.sh_entsize = _w(rel_entsize);
-
- if (uwrite(&mcsec, sizeof(mcsec)) < 0)
+ /* add section: __mcount_loc */
+ sec = elf_create_section(lf, mc_name + (sizeof(Elf_Rela) == rel_entsize) + strlen(".rel"), _size, mlocp - mloc0);
+ if (!sec)
return -1;
- if (uwrite(mloc0, (void *)mlocp - (void *)mloc0) < 0)
- return -1;
- if (uwrite(mrel0, (void *)mrelp - (void *)mrel0) < 0)
+ // created sec->sh.sh_size = (void *)mlocp - (void *)mloc0;
+ sec->sh.sh_link = 0;/* TODO objtool uses this? */
+ sec->sh.sh_info = 0;/* TODO objtool uses this? */
+ sec->sh.sh_addralign = _size;
+ // created sec->sh.sh_entsize = _size;
+
+ // assert sec->data->d_size == (void *)mlocp - (void *)mloc0
+ memcpy(sec->data->d_buf, mloc0, sec->data->d_size);
+ /* HACK link in Pre-assembled buffer ?
+ sec->data->d_buf = mloc0;
+ sec->data->d_size = sec->sh.sh_size;*/
+
+ /* add section .rel[a]__mcount_loc */
+ sec = elf_create_section(lf, mc_name, rel_entsize, mrelp - mrel0);
+ if (!sec)
return -1;
+ sec->sh.sh_type = (sizeof(Elf_Rela) == rel_entsize)
+ ? SHT_RELA
+ : SHT_REL;
+ sec->sh.sh_flags = 0;
+ sec->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
+ sec->sh.sh_info = old_shnum;
+ sec->sh.sh_addralign = _size;
+
+ // assert sec->data->d_size == (void *)mrelp - (void *)mrel0
+ memcpy(sec->data->d_buf, mrel0, sec->data->d_size);
+ /* HACK link in Pre-assembled buffer ?
+ sec->data->d_buf = mrel0;
+ sec->data->d_size = sec->sh.sh_size;*/
- ehdr->e_shoff = _w(new_e_shoff);
- ehdr->e_shnum = w2(2 + lf->ehdr.e_shnum); /* {.rel,}__mcount_loc */
- if (ulseek(0, SEEK_SET) < 0)
- return -1;
- if (uwrite(ehdr, sizeof(*ehdr)) < 0)
- return -1;
return elf_write(lf);
}
@@ -223,13 +177,10 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
* into nops.
*/
static int nop_mcount(struct section * const rels,
- Elf_Ehdr const *const ehdr,
const char *const txtname)
{
- Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
- + (void *)ehdr);
struct reloc *reloc;
- Elf_Shdr const *const shdr = &shdr0[rels->sh.sh_info];
+ struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
unsigned mcountsym = 0;
int once = 0;
@@ -241,7 +192,7 @@ static int nop_mcount(struct section * const rels,
if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
if (make_nop) {
- ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + reloc->offset);
+ ret = make_nop(txts, reloc->offset);
if (ret < 0)
return -1;
}
@@ -296,12 +247,8 @@ static unsigned tot_relsize(void)
/* Overall supervision for Elf32 ET_REL file. */
-static int do_func(Elf_Ehdr *const ehdr,
- unsigned const reltype)
+static int do_func(unsigned const reltype)
{
- Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
- + (void *)ehdr);
-
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -360,15 +307,14 @@ static int do_func(Elf_Ehdr *const ehdr,
* This section is ignored by ftrace, but still
* has mcount calls. Convert them to nops now.
*/
- if (nop_mcount(sec, ehdr, txtname) < 0) {
+ if (nop_mcount(sec, txtname) < 0) {
result = -1;
goto out;
}
}
}
if (!result && mloc0 != mlocp)
- result = append_func(ehdr, &shdr0[w2(ehdr->e_shstrndx)],
- mloc0, mlocp, mrel0, mrelp,
+ result = append_func(mloc0, mlocp, mrel0, mrelp,
rel_entsize, symsec_sh_link);
out:
free(mrel0);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (16 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-12 13:26 ` Peter Zijlstra
2020-06-02 19:50 ` [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
` (13 subsequent siblings)
31 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The nop_mcount() function overwrites mcount calls that should be
ignored with no-ops. This operation varies by architecture and
wordsize so we retain the function pointers used to implement
the fundamental operation while nop_mcount() itself is responsible
for walking the relocations, determining if they should be turned
into no-ops, then calling the arch-specific code. Since none of
these use the recordmcount ELF wrappers anymore we can move it out
of the wrapper.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 47 +++++++++++++++++++++++++++++++++
tools/objtool/recordmcount.h | 50 ------------------------------------
2 files changed, 47 insertions(+), 50 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 89762908290e..88998a505859 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -398,6 +398,53 @@ static int find_section_sym_index(unsigned const txtndx,
return missing_sym;
}
+/*
+ * Read the relocation table again, but this time its called on sections
+ * that are not going to be traced. The mcount calls here will be converted
+ * into nops.
+ */
+static int nop_mcount(struct section * const rels,
+ const char *const txtname)
+{
+ struct reloc *reloc;
+ struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
+ unsigned mcountsym = 0;
+ int once = 0;
+
+ list_for_each_entry(reloc, &rels->reloc_list, list) {
+ int ret = -1;
+
+ if (!mcountsym)
+ mcountsym = get_mcountsym(reloc);
+
+ if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
+ if (make_nop) {
+ ret = make_nop(txts, reloc->offset);
+ if (ret < 0)
+ return -1;
+ }
+ if (warn_on_notrace_sect && !once) {
+ printf("Section %s has mcount callers being ignored\n",
+ txtname);
+ once = 1;
+ /* just warn? */
+ if (!make_nop)
+ return 0;
+ }
+ }
+
+ /*
+ * If we successfully removed the mcount, mark the relocation
+ * as a nop (don't do anything with it).
+ */
+ if (!ret) {
+ reloc->type = rel_type_nop;
+ rels->changed = true;
+ }
+ }
+ return 0;
+}
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 6754bde0bacc..e033b600bd61 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -20,7 +20,6 @@
#undef append_func
#undef mcount_adjust
#undef sift_rel_mcount
-#undef nop_mcount
#undef has_rel_mcount
#undef tot_relsize
#undef do_func
@@ -37,7 +36,6 @@
#ifdef RECORD_MCOUNT_64
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
-# define nop_mcount nop_mcount_64
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
# define do_func do64
@@ -53,7 +51,6 @@
#else
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
-# define nop_mcount nop_mcount_32
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
# define do_func do32
@@ -171,53 +168,6 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
return mlocp;
}
-/*
- * Read the relocation table again, but this time its called on sections
- * that are not going to be traced. The mcount calls here will be converted
- * into nops.
- */
-static int nop_mcount(struct section * const rels,
- const char *const txtname)
-{
- struct reloc *reloc;
- struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- unsigned mcountsym = 0;
- int once = 0;
-
- list_for_each_entry(reloc, &rels->reloc_list, list) {
- int ret = -1;
-
- if (!mcountsym)
- mcountsym = get_mcountsym(reloc);
-
- if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
- if (make_nop) {
- ret = make_nop(txts, reloc->offset);
- if (ret < 0)
- return -1;
- }
- if (warn_on_notrace_sect && !once) {
- printf("Section %s has mcount callers being ignored\n",
- txtname);
- once = 1;
- /* just warn? */
- if (!make_nop)
- return 0;
- }
- }
-
- /*
- * If we successfully removed the mcount, mark the relocation
- * as a nop (don't do anything with it).
- */
- if (!ret) {
- reloc->type = rel_type_nop;
- rels->changed = true;
- }
- }
- return 0;
-}
-
static char const *has_rel_mcount(const struct section * const rels)
{
const struct section *txts;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize()
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (17 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection Matt Helsley
` (12 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The has_rel_mcount() and tot_relsize() helpers are no longer
dependent on the ELF wrapper so we can move them.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 25 +++++++++++++++++++++++++
tools/objtool/recordmcount.h | 33 ---------------------------------
2 files changed, 25 insertions(+), 33 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 88998a505859..248e49033538 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -445,6 +445,31 @@ static int nop_mcount(struct section * const rels,
return 0;
}
+static char const *has_rel_mcount(const struct section * const rels)
+{
+ const struct section *txts;
+ if (rels->sh.sh_type != SHT_REL && rels->sh.sh_type != SHT_RELA)
+ return NULL;
+ txts = find_section_by_index(lf, rels->sh.sh_info);
+ if ((txts->sh.sh_type != SHT_PROGBITS) ||
+ !(txts->sh.sh_flags & SHF_EXECINSTR))
+ return NULL;
+ return txts->name;
+}
+
+static unsigned tot_relsize(void)
+{
+ const struct section *sec;
+ unsigned totrelsz = 0;
+ char const *txtname;
+
+ list_for_each_entry(sec, &lf->sections, list) {
+ txtname = has_rel_mcount(sec);
+ if (txtname && is_mcounted_section_name(txtname))
+ totrelsz += sec->sh.sh_size;
+ }
+ return totrelsz;
+}
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index e033b600bd61..f8d3e81c0129 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -20,8 +20,6 @@
#undef append_func
#undef mcount_adjust
#undef sift_rel_mcount
-#undef has_rel_mcount
-#undef tot_relsize
#undef do_func
#undef Elf_Shdr
#undef Elf_Rel
@@ -36,8 +34,6 @@
#ifdef RECORD_MCOUNT_64
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
-# define has_rel_mcount has64_rel_mcount
-# define tot_relsize tot64_relsize
# define do_func do64
# define mcount_adjust mcount_adjust_64
# define Elf_Rel Elf64_Rel
@@ -51,8 +47,6 @@
#else
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
-# define has_rel_mcount has32_rel_mcount
-# define tot_relsize tot32_relsize
# define do_func do32
# define mcount_adjust mcount_adjust_32
# define Elf_Rel Elf32_Rel
@@ -168,33 +162,6 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
return mlocp;
}
-static char const *has_rel_mcount(const struct section * const rels)
-{
- const struct section *txts;
- if (rels->sh.sh_type != SHT_REL && rels->sh.sh_type != SHT_RELA)
- return NULL;
- txts = find_section_by_index(lf, rels->sh.sh_info);
- if ((txts->sh.sh_type != SHT_PROGBITS) ||
- !(txts->sh.sh_flags & SHF_EXECINSTR))
- return NULL;
- return txts->name;
-}
-
-
-static unsigned tot_relsize(void)
-{
- const struct section *sec;
- unsigned totrelsz = 0;
- char const *txtname;
-
- list_for_each_entry(sec, &lf->sections, list) {
- txtname = has_rel_mcount(sec);
- if (txtname && is_mcounted_section_name(txtname))
- totrelsz += sec->sh.sh_size;
- }
- return totrelsz;
-}
-
/* Overall supervision for Elf32 ET_REL file. */
static int do_func(unsigned const reltype)
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (18 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size Matt Helsley
` (11 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Move where we detect the size of relocation entries we wish to
use into the first loop over the sections. This will allow us
to allocate the mcount location and relocation sections before
the next loop that collects them.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 8 +++++---
tools/objtool/recordmcount.h | 5 ++---
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 248e49033538..6feb4e6b4113 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -457,7 +457,7 @@ static char const *has_rel_mcount(const struct section * const rels)
return txts->name;
}
-static unsigned tot_relsize(void)
+static unsigned tot_relsize(unsigned int *rel_entsize)
{
const struct section *sec;
unsigned totrelsz = 0;
@@ -465,8 +465,10 @@ static unsigned tot_relsize(void)
list_for_each_entry(sec, &lf->sections, list) {
txtname = has_rel_mcount(sec);
- if (txtname && is_mcounted_section_name(txtname))
- totrelsz += sec->sh.sh_size;
+ if (!(txtname && is_mcounted_section_name(txtname)))
+ continue;
+ totrelsz += sec->sh.sh_size;
+ *rel_entsize = sec->sh.sh_entsize;
}
return totrelsz;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index f8d3e81c0129..352d2042be35 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -175,7 +175,7 @@ static int do_func(unsigned const reltype)
uint_t * mloc0;
uint_t * mlocp;
- unsigned rel_entsize = 0;
+ unsigned int rel_entsize = 0;
unsigned symsec_sh_link = 0;
struct section *sec;
@@ -185,7 +185,7 @@ static int do_func(unsigned const reltype)
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
- totrelsz = tot_relsize();
+ totrelsz = tot_relsize(&rel_entsize);
if (totrelsz == 0)
return 0;
mrel0 = umalloc(totrelsz);
@@ -215,7 +215,6 @@ static int do_func(unsigned const reltype)
if (result)
goto out;
- rel_entsize = sec->sh.sh_entsize;
mlocp = sift_rel_mcount(mlocp,
(void *)mlocp - (void *)mloc0, &mrelp,
sec, recsym, (uint_t)recval, reltype);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (19 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool Matt Helsley
` (10 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Since we're no longer writing to the ELF file mapping and we're
not appending to it we don't need to keep more information from the
stat structure. At the same time we can give the smaller global
variable a better name.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 6feb4e6b4113..85e95e1ea6f6 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -48,17 +48,17 @@
static int fd_map; /* File descriptor for file being modified. */
static int mmap_failed; /* Boolean flag. */
static char gpfx; /* prefix for global symbol name (sometimes '_') */
-static struct stat sb; /* Remember .st_size, etc. */
static const char *altmcount; /* alternate mcount symbol name */
extern int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
static void *file_map; /* pointer of the mapped file */
+static size_t file_map_size; /* original ELF file size */
static struct elf *lf;
static void mmap_cleanup(void)
{
if (!mmap_failed)
- munmap(file_map, sb.st_size);
+ munmap(file_map, file_map_size);
else
free(file_map);
file_map = NULL;
@@ -93,11 +93,13 @@ static void * umalloc(size_t size)
*/
static void *mmap_file(char const *fname)
{
+ struct stat sb;
+
/* Avoid problems if early cleanup() */
fd_map = -1;
mmap_failed = 1;
file_map = NULL;
- sb.st_size = 0;
+ file_map_size = 0;
lf = elf_open_read(fname, O_RDWR);
if (!lf) {
@@ -129,6 +131,7 @@ static void *mmap_file(char const *fname)
}
} else
mmap_failed = 0;
+ file_map_size = sb.st_size;
out:
fd_map = -1;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (20 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping Matt Helsley
` (9 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The ELF header is the very first structure in an ELF file.
Rather than cast it from the file mapping we use the ELF
header extracted via objtool's ELF code.
This is the last usage of the open-coded mapping of the ELF
file which we will remove in a later step.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 37 +++++++++++++++++-------------------
1 file changed, 17 insertions(+), 20 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 85e95e1ea6f6..bfed27f53f75 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -523,21 +523,19 @@ static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
static int do_file(char const *const fname)
{
unsigned int reltype = 0;
- Elf32_Ehdr *ehdr;
int rc = -1;
- ehdr = mmap_file(fname);
- if (!ehdr)
+ if (!mmap_file(fname))
goto out;
w = w4nat;
w2 = w2nat;
w8 = w8nat;
- switch (ehdr->e_ident[EI_DATA]) {
+ switch (lf->ehdr.e_ident[EI_DATA]) {
static unsigned int const endian = 1;
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
- ehdr->e_ident[EI_DATA], fname);
+ lf->ehdr.e_ident[EI_DATA], fname);
goto out;
case ELFDATA2LSB:
if (*(unsigned char const *)&endian != 1) {
@@ -566,18 +564,18 @@ static int do_file(char const *const fname)
push_bl_mcount_thumb = push_bl_mcount_thumb_be;
break;
} /* end switch */
- if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 ||
- w2(ehdr->e_type) != ET_REL ||
- ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+ if (memcmp(ELFMAG, lf->ehdr.e_ident, SELFMAG) != 0 ||
+ lf->ehdr.e_type != ET_REL ||
+ lf->ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
goto out;
}
gpfx = '_';
- switch (w2(ehdr->e_machine)) {
+ switch (lf->ehdr.e_machine) {
default:
fprintf(stderr, "unrecognized e_machine %u %s\n",
- w2(ehdr->e_machine), fname);
+ lf->ehdr.e_machine, fname);
goto out;
case EM_386:
reltype = R_386_32;
@@ -618,37 +616,36 @@ static int do_file(char const *const fname)
break;
} /* end switch */
- switch (ehdr->e_ident[EI_CLASS]) {
+ switch (lf->ehdr.e_ident[EI_CLASS]) {
default:
fprintf(stderr, "unrecognized ELF class %d %s\n",
- ehdr->e_ident[EI_CLASS], fname);
+ lf->ehdr.e_ident[EI_CLASS], fname);
goto out;
case ELFCLASS32:
- if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
- || w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
+ if (lf->ehdr.e_ehsize != sizeof(Elf32_Ehdr)
+ || lf->ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_REL file: %s\n", fname);
goto out;
}
- if (w2(ehdr->e_machine) == EM_MIPS) {
+ if (lf->ehdr.e_machine == EM_MIPS) {
reltype = R_MIPS_32;
is_fake_mcount = MIPS_is_fake_mcount;
}
rc = do32(reltype);
break;
case ELFCLASS64: {
- Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
- if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
- || w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
+ if (lf->ehdr.e_ehsize != sizeof(Elf64_Ehdr)
+ || lf->ehdr.e_shentsize != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_REL file: %s\n", fname);
goto out;
}
- if (w2(ghdr->e_machine) == EM_S390) {
+ if (lf->ehdr.e_machine == EM_S390) {
reltype = R_390_64;
mcount_adjust_64 = -14;
}
- if (w2(ghdr->e_machine) == EM_MIPS) {
+ if (lf->ehdr.e_machine == EM_MIPS) {
reltype = R_MIPS_64;
Elf64_r_info = MIPS64_r_info;
is_fake_mcount = MIPS_is_fake_mcount;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (21 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
` (8 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The ELF data is now accessed completely through objtool's
ELF code. We can remove the mapping of the original ELF
file and propagate elf_open_read(), elf_close(), and malloc()
up in place of mmap_file(), mmap_cleanup(), and umalloc()
respectively. This also eliminates the last use of the
umalloc() wrapper, reduces the number of global
variables, and limits the use of globals to:
The struct elf for the file we're working on. This
saves passing it to nearly every function as a parameter.
Variables set depending on the ELF file endian, wordsize,
and arch so that the appropriate relocation structures,
offset sizes, architecture quirks, and nop encodings will
be used.
One command-line option
Note that we're still using the recordmcount wrapper to change
variable sizes and structure definitions we use to build the
mcount relocation data and call instruction offsets.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 99 +++---------------------------------
tools/objtool/recordmcount.h | 4 +-
2 files changed, 9 insertions(+), 94 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index bfed27f53f75..5ec44c9f2884 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -41,104 +41,14 @@
#define R_AARCH64_ABS64 257
#endif
-#define R_ARM_PC24 1
#define R_ARM_THM_CALL 10
-#define R_ARM_CALL 28
-static int fd_map; /* File descriptor for file being modified. */
-static int mmap_failed; /* Boolean flag. */
static char gpfx; /* prefix for global symbol name (sometimes '_') */
static const char *altmcount; /* alternate mcount symbol name */
extern int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
-static void *file_map; /* pointer of the mapped file */
-static size_t file_map_size; /* original ELF file size */
static struct elf *lf;
-static void mmap_cleanup(void)
-{
- if (!mmap_failed)
- munmap(file_map, file_map_size);
- else
- free(file_map);
- file_map = NULL;
- if (lf)
- elf_close(lf);
- lf = NULL;
-}
-
-static void * umalloc(size_t size)
-{
- void *const addr = malloc(size);
- if (addr == 0) {
- fprintf(stderr, "malloc failed: %zu bytes\n", size);
- mmap_cleanup();
- return NULL;
- }
- return addr;
-}
-
-/*
- * Get the whole file as a programming convenience in order to avoid
- * malloc+lseek+read+free of many pieces. If successful, then mmap
- * avoids copying unused pieces; else just read the whole file.
- * Open for both read and write; new info will be appended to the file.
- * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
- * do not propagate to the file until an explicit overwrite at the last.
- * This preserves most aspects of consistency (all except .st_size)
- * for simultaneous readers of the file while we are appending to it.
- * However, multiple writers still are bad. We choose not to use
- * locking because it is expensive and the use case of kernel build
- * makes multiple writers unlikely.
- */
-static void *mmap_file(char const *fname)
-{
- struct stat sb;
-
- /* Avoid problems if early cleanup() */
- fd_map = -1;
- mmap_failed = 1;
- file_map = NULL;
- file_map_size = 0;
-
- lf = elf_open_read(fname, O_RDWR);
- if (!lf) {
- perror(fname);
- return NULL;
- }
- fd_map = lf->fd;
- if (fstat(fd_map, &sb) < 0) {
- perror(fname);
- goto out;
- }
- if (!S_ISREG(sb.st_mode)) {
- fprintf(stderr, "not a regular file: %s\n", fname);
- goto out;
- }
- file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
- fd_map, 0);
- if (file_map == MAP_FAILED) {
- mmap_failed = 1;
- file_map = umalloc(sb.st_size);
- if (!file_map) {
- perror(fname);
- goto out;
- }
- if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
- perror(fname);
- mmap_cleanup();
- goto out;
- }
- } else
- mmap_failed = 0;
- file_map_size = sb.st_size;
-out:
- fd_map = -1;
-
- return file_map;
-}
-
-
static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
static unsigned char *ideal_nop;
@@ -525,8 +435,11 @@ static int do_file(char const *const fname)
unsigned int reltype = 0;
int rc = -1;
- if (!mmap_file(fname))
+ lf = elf_open_read(fname, O_RDWR);
+ if (!lf) {
+ perror(fname);
goto out;
+ }
w = w4nat;
w2 = w2nat;
@@ -656,7 +569,9 @@ static int do_file(char const *const fname)
} /* end switch */
out:
- mmap_cleanup();
+ if (lf)
+ elf_close(lf);
+ lf = NULL;
return rc;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 352d2042be35..e1be7243742b 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -188,13 +188,13 @@ static int do_func(unsigned const reltype)
totrelsz = tot_relsize(&rel_entsize);
if (totrelsz == 0)
return 0;
- mrel0 = umalloc(totrelsz);
+ mrel0 = malloc(totrelsz);
mrelp = mrel0;
if (!mrel0)
return -1;
/* 2*sizeof(address) <= sizeof(Elf_Rel) */
- mloc0 = umalloc(totrelsz>>1);
+ mloc0 = malloc(totrelsz>>1);
mlocp = mloc0;
if (!mloc0) {
free(mrel0);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (22 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
` (7 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Use a new loc_size parameter to append_func() rather than
use the wrapper's _size macro directly.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index e1be7243742b..e2de71f99566 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -72,6 +72,7 @@ static int append_func(uint_t const *const mloc0,
uint_t const *const mlocp,
Elf_Rel const *const mrel0,
Elf_Rel const *const mrelp,
+ unsigned int const loc_size,
unsigned int const rel_entsize,
unsigned int const symsec_sh_link)
{
@@ -83,14 +84,14 @@ static int append_func(uint_t const *const mloc0,
unsigned const old_shnum = lf->ehdr.e_shnum;
/* add section: __mcount_loc */
- sec = elf_create_section(lf, mc_name + (sizeof(Elf_Rela) == rel_entsize) + strlen(".rel"), _size, mlocp - mloc0);
+ sec = elf_create_section(lf, mc_name + (sizeof(Elf_Rela) == rel_entsize) + strlen(".rel"), loc_size, mlocp - mloc0);
if (!sec)
return -1;
// created sec->sh.sh_size = (void *)mlocp - (void *)mloc0;
sec->sh.sh_link = 0;/* TODO objtool uses this? */
sec->sh.sh_info = 0;/* TODO objtool uses this? */
- sec->sh.sh_addralign = _size;
+ sec->sh.sh_addralign = loc_size;
// created sec->sh.sh_entsize = _size;
// assert sec->data->d_size == (void *)mlocp - (void *)mloc0
@@ -109,7 +110,7 @@ static int append_func(uint_t const *const mloc0,
sec->sh.sh_flags = 0;
sec->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
sec->sh.sh_info = old_shnum;
- sec->sh.sh_addralign = _size;
+ sec->sh.sh_addralign = loc_size;
// assert sec->data->d_size == (void *)mrelp - (void *)mrel0
memcpy(sec->data->d_buf, mrel0, sec->data->d_size);
@@ -231,7 +232,7 @@ static int do_func(unsigned const reltype)
}
if (!result && mloc0 != mlocp)
result = append_func(mloc0, mlocp, mrel0, mrelp,
- rel_entsize, symsec_sh_link);
+ _size, rel_entsize, symsec_sh_link);
out:
free(mrel0);
free(mloc0);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (23 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
` (6 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
The mcount_adjust variable defines how many bytes to move back
from the relocation address in order to be able to get to the
start of the function call instruction(s) needed to turn it
into a no-op. The values are very small and signed so we don't
need to worry about changing the size of the variable's type
inside the wrapper -- we can just use a regular int.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 12 +++++++++---
tools/objtool/recordmcount.h | 5 -----
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 5ec44c9f2884..06a8f8ddefa7 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -385,6 +385,12 @@ static unsigned tot_relsize(unsigned int *rel_entsize)
}
return totrelsz;
}
+
+/* zero or a small negative offset added to get the start of the call
+ * instruction
+ */
+static int mcount_adjust = 0;
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
@@ -495,7 +501,7 @@ static int do_file(char const *const fname)
rel_type_nop = R_386_NONE;
make_nop = make_nop_x86;
ideal_nop = ideal_nop5_x86_32;
- mcount_adjust_32 = -1;
+ mcount_adjust = -1;
gpfx = 0;
break;
case EM_ARM:
@@ -524,7 +530,7 @@ static int do_file(char const *const fname)
ideal_nop = ideal_nop5_x86_64;
reltype = R_X86_64_64;
rel_type_nop = R_X86_64_NONE;
- mcount_adjust_64 = -1;
+ mcount_adjust = -1;
gpfx = 0;
break;
} /* end switch */
@@ -556,7 +562,7 @@ static int do_file(char const *const fname)
}
if (lf->ehdr.e_machine == EM_S390) {
reltype = R_390_64;
- mcount_adjust_64 = -14;
+ mcount_adjust = -14;
}
if (lf->ehdr.e_machine == EM_MIPS) {
reltype = R_MIPS_64;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index e2de71f99566..853c4006a34f 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -18,7 +18,6 @@
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
#undef append_func
-#undef mcount_adjust
#undef sift_rel_mcount
#undef do_func
#undef Elf_Shdr
@@ -35,7 +34,6 @@
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
# define do_func do64
-# define mcount_adjust mcount_adjust_64
# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
# define ELF_R_INFO ELF64_R_INFO
@@ -48,7 +46,6 @@
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
# define do_func do32
-# define mcount_adjust mcount_adjust_32
# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
# define ELF_R_INFO ELF32_R_INFO
@@ -65,8 +62,6 @@ static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
}
static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
-static int mcount_adjust = 0;
-
/* Append the new __mcount_loc and its relocations. */
static int append_func(uint_t const *const mloc0,
uint_t const *const mlocp,
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (24 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
` (5 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than allocating the ELF sections after collecting the
mcount locations and building the relocation entries, create
the empty sections beforehand. This has the benefit of
removing the memcpy() and just using the resulting libgelf
buffers directly.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.h | 122 +++++++++++++++--------------------
1 file changed, 52 insertions(+), 70 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 853c4006a34f..de31ff003032 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -17,7 +17,6 @@
* This conversion to macros was done by:
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
-#undef append_func
#undef sift_rel_mcount
#undef do_func
#undef Elf_Shdr
@@ -31,7 +30,6 @@
#undef _size
#ifdef RECORD_MCOUNT_64
-# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
# define do_func do64
# define Elf_Rel Elf64_Rel
@@ -43,7 +41,6 @@
# define _w w8
# define _size 8
#else
-# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
# define do_func do32
# define Elf_Rel Elf32_Rel
@@ -62,60 +59,6 @@ static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
}
static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
-/* Append the new __mcount_loc and its relocations. */
-static int append_func(uint_t const *const mloc0,
- uint_t const *const mlocp,
- Elf_Rel const *const mrel0,
- Elf_Rel const *const mrelp,
- unsigned int const loc_size,
- unsigned int const rel_entsize,
- unsigned int const symsec_sh_link)
-{
- /* Begin constructing output file */
- struct section *sec;
- char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
- ? ".rela__mcount_loc"
- : ".rel__mcount_loc";
- unsigned const old_shnum = lf->ehdr.e_shnum;
-
- /* add section: __mcount_loc */
- sec = elf_create_section(lf, mc_name + (sizeof(Elf_Rela) == rel_entsize) + strlen(".rel"), loc_size, mlocp - mloc0);
- if (!sec)
- return -1;
-
- // created sec->sh.sh_size = (void *)mlocp - (void *)mloc0;
- sec->sh.sh_link = 0;/* TODO objtool uses this? */
- sec->sh.sh_info = 0;/* TODO objtool uses this? */
- sec->sh.sh_addralign = loc_size;
- // created sec->sh.sh_entsize = _size;
-
- // assert sec->data->d_size == (void *)mlocp - (void *)mloc0
- memcpy(sec->data->d_buf, mloc0, sec->data->d_size);
- /* HACK link in Pre-assembled buffer ?
- sec->data->d_buf = mloc0;
- sec->data->d_size = sec->sh.sh_size;*/
-
- /* add section .rel[a]__mcount_loc */
- sec = elf_create_section(lf, mc_name, rel_entsize, mrelp - mrel0);
- if (!sec)
- return -1;
- sec->sh.sh_type = (sizeof(Elf_Rela) == rel_entsize)
- ? SHT_RELA
- : SHT_REL;
- sec->sh.sh_flags = 0;
- sec->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
- sec->sh.sh_info = old_shnum;
- sec->sh.sh_addralign = loc_size;
-
- // assert sec->data->d_size == (void *)mrelp - (void *)mrel0
- memcpy(sec->data->d_buf, mrel0, sec->data->d_size);
- /* HACK link in Pre-assembled buffer ?
- sec->data->d_buf = mrel0;
- sec->data->d_size = sec->sh.sh_size;*/
-
- return elf_write(lf);
-}
-
/*
* Look at the relocations in order to find the calls to mcount.
* Accumulate the section offsets that are found, and their relocation info,
@@ -172,11 +115,13 @@ static int do_func(unsigned const reltype)
uint_t * mlocp;
unsigned int rel_entsize = 0;
- unsigned symsec_sh_link = 0;
- struct section *sec;
+ struct section *sec, *mlocs, *mrels;
+ unsigned int const old_shnum = lf->ehdr.e_shnum;
- int result = 0;
+ int result = -1;
+ char const *mc_name;
+ bool is_rela;
if (find_section_by_name(lf, "__mcount_loc") != NULL)
return 0;
@@ -184,6 +129,7 @@ static int do_func(unsigned const reltype)
totrelsz = tot_relsize(&rel_entsize);
if (totrelsz == 0)
return 0;
+
mrel0 = malloc(totrelsz);
mrelp = mrel0;
if (!mrel0)
@@ -197,6 +143,32 @@ static int do_func(unsigned const reltype)
return -1;
}
+ is_rela = (sizeof(Elf_Rela) == rel_entsize);
+ mc_name = is_rela
+ ? ".rela__mcount_loc"
+ : ".rel__mcount_loc";
+
+ /* add section: __mcount_loc */
+ mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), _size, 0);
+ if (!mlocs)
+ goto out;
+
+ mlocs->sh.sh_link = 0;
+ mlocs->sh.sh_info = 0;
+ mlocs->sh.sh_addralign = _size;
+
+ /* add section .rel[a]__mcount_loc */
+ mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
+ if (!mrels)
+ goto out;
+ mrels->sh.sh_type = is_rela
+ ? SHT_RELA
+ : SHT_REL;
+ mrels->sh.sh_flags = 0;
+ mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
+ mrels->sh.sh_info = old_shnum;
+ mrels->sh.sh_addralign = _size;
+
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
@@ -205,10 +177,8 @@ static int do_func(unsigned const reltype)
unsigned long recval = 0;
unsigned int recsym;
- symsec_sh_link = sec->sh.sh_link;
- result = find_section_sym_index(sec->sh.sh_info,
- txtname, &recval, &recsym);
- if (result)
+ if (find_section_sym_index(sec->sh.sh_info,
+ txtname, &recval, &recsym))
goto out;
mlocp = sift_rel_mcount(mlocp,
@@ -219,15 +189,27 @@ static int do_func(unsigned const reltype)
* This section is ignored by ftrace, but still
* has mcount calls. Convert them to nops now.
*/
- if (nop_mcount(sec, txtname) < 0) {
- result = -1;
+ if (nop_mcount(sec, txtname) < 0)
goto out;
- }
}
}
- if (!result && mloc0 != mlocp)
- result = append_func(mloc0, mlocp, mrel0, mrelp,
- _size, rel_entsize, symsec_sh_link);
+
+ if (mloc0 != mlocp) {
+ /* Update the section sizes */
+ mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
+ mlocs->len = mlocs->sh.sh_size;
+ mlocs->data->d_size = mlocs->len;
+ mlocs->data->d_buf = mloc0;
+
+ mrels->sh.sh_size = (void *)mrelp - (void *)mrel0;
+ mrels->len = mrels->sh.sh_size;
+ mrels->data->d_size = mrels->len;
+ mrels->data->d_buf = mrel0;
+
+ /* overwrite the ELF file */
+ result = elf_write(lf);
+ } else
+ result = 0;
out:
free(mrel0);
free(mloc0);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (25 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-09 6:41 ` Kamalesh Babulal
2020-06-02 19:50 ` [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
` (4 subsequent siblings)
31 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Rather than building the exact ELF section data we need and
avoiding libelf's conversion step, use more GElf types
and then libelf's elfxx_xlatetof() functions to convert
the mcount locations (GElf_Addr) and associated relocations.
This converts sift_rel_mcount() so that it doesn't use the
recordmcount wrapper. The next patch will move it out of the
wrapper.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 44 +++----------
tools/objtool/recordmcount.h | 120 ++++++++++++++---------------------
2 files changed, 59 insertions(+), 105 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 06a8f8ddefa7..ef3c360a3db9 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -210,7 +210,7 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static unsigned get_mcountsym(struct reloc *reloc)
+static unsigned int get_mcount_sym_info(struct reloc *reloc)
{
struct symbol *sym = reloc->sym;
char const *symname = sym->name;
@@ -321,16 +321,16 @@ static int nop_mcount(struct section * const rels,
{
struct reloc *reloc;
struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- unsigned mcountsym = 0;
+ unsigned int mcount_sym_info = 0;
int once = 0;
list_for_each_entry(reloc, &rels->reloc_list, list) {
int ret = -1;
- if (!mcountsym)
- mcountsym = get_mcountsym(reloc);
+ if (!mcount_sym_info)
+ mcount_sym_info = get_mcount_sym_info(reloc);
- if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
+ if (mcount_sym_info == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
if (make_nop) {
ret = make_nop(txts, reloc->offset);
if (ret < 0)
@@ -391,6 +391,9 @@ static unsigned tot_relsize(unsigned int *rel_entsize)
*/
static int mcount_adjust = 0;
+/* Size of an entry in __mcount_loc; 4 or 8 */
+static size_t loc_size;
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
@@ -408,34 +411,6 @@ static int arm_is_fake_mcount(struct reloc const *rp)
return 1;
}
-/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
- * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
- * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
- * to imply the order of the members; the spec does not say so.
- * typedef unsigned char Elf64_Byte;
- * fails on MIPS64 because their <elf.h> already has it!
- */
-
-typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */
-
-union mips_r_info {
- Elf64_Xword r_info;
- struct {
- Elf64_Word r_sym; /* Symbol index. */
- myElf64_Byte r_ssym; /* Special symbol. */
- myElf64_Byte r_type3; /* Third relocation. */
- myElf64_Byte r_type2; /* Second relocation. */
- myElf64_Byte r_type; /* First relocation. */
- } r_mips;
-};
-
-static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
-{
- rp->r_info = ((union mips_r_info){
- .r_mips = { .r_sym = w(sym), .r_type = type }
- }).r_info;
-}
-
static int do_file(char const *const fname)
{
unsigned int reltype = 0;
@@ -551,6 +526,7 @@ static int do_file(char const *const fname)
reltype = R_MIPS_32;
is_fake_mcount = MIPS_is_fake_mcount;
}
+ loc_size = 4;
rc = do32(reltype);
break;
case ELFCLASS64: {
@@ -566,9 +542,9 @@ static int do_file(char const *const fname)
}
if (lf->ehdr.e_machine == EM_MIPS) {
reltype = R_MIPS_64;
- Elf64_r_info = MIPS64_r_info;
is_fake_mcount = MIPS_is_fake_mcount;
}
+ loc_size = 8;
rc = do64(reltype);
break;
}
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index de31ff003032..b58f0cc58f76 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -19,86 +19,63 @@
*/
#undef sift_rel_mcount
#undef do_func
-#undef Elf_Shdr
-#undef Elf_Rel
#undef Elf_Rela
-#undef ELF_R_INFO
-#undef Elf_r_info
-#undef fn_ELF_R_INFO
-#undef uint_t
-#undef _w
-#undef _size
#ifdef RECORD_MCOUNT_64
# define sift_rel_mcount sift64_rel_mcount
# define do_func do64
-# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
-# define ELF_R_INFO ELF64_R_INFO
-# define Elf_r_info Elf64_r_info
-# define fn_ELF_R_INFO fn_ELF64_R_INFO
-# define uint_t uint64_t
-# define _w w8
-# define _size 8
#else
# define sift_rel_mcount sift32_rel_mcount
# define do_func do32
-# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
-# define ELF_R_INFO ELF32_R_INFO
-# define Elf_r_info Elf32_r_info
-# define fn_ELF_R_INFO fn_ELF32_R_INFO
-# define uint_t uint32_t
-# define _w w
-# define _size 4
#endif
-static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
-{
- rp->r_info = _w(ELF_R_INFO(sym, type));
-}
-static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
-
/*
* Look at the relocations in order to find the calls to mcount.
* Accumulate the section offsets that are found, and their relocation info,
* onto the end of the existing arrays.
*/
-static uint_t *sift_rel_mcount(uint_t *mlocp,
- unsigned const offbase,
- Elf_Rel **const mrelpp,
+static void sift_rel_mcount(GElf_Addr **mlocpp,
+ GElf_Sxword *r_offsetp,
+ void **const mrelpp,
const struct section * const rels,
unsigned const recsym_index,
unsigned long const recval,
- unsigned const reltype)
+ unsigned const reltype,
+ bool is_rela)
{
- uint_t *const mloc0 = mlocp;
- Elf_Rel *mrelp = *mrelpp;
- unsigned int rel_entsize = rels->sh.sh_entsize;
- unsigned mcountsym = 0;
+ GElf_Rel *mrelp = *mrelpp;
+ GElf_Rela *mrelap = *mrelpp;
+ unsigned int mcount_sym_info = 0;
struct reloc *reloc;
list_for_each_entry(reloc, &rels->reloc_list, list) {
- if (!mcountsym)
- mcountsym = get_mcountsym(reloc);
-
- if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
- uint_t const addend =
- _w(reloc->offset - recval + mcount_adjust);
- mrelp->r_offset = _w(offbase
- + ((void *)mlocp - (void *)mloc0));
- Elf_r_info(mrelp, recsym_index, reltype);
- if (rel_entsize == sizeof(Elf_Rela)) {
- ((Elf_Rela *)mrelp)->r_addend = addend;
- *mlocp++ = 0;
- } else
- *mlocp++ = addend;
-
- mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
+ unsigned long addend;
+
+ if (!mcount_sym_info)
+ mcount_sym_info = get_mcount_sym_info(reloc);
+
+ if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
+ continue;
+
+ addend = reloc->offset - recval + mcount_adjust;
+ if (is_rela) {
+ mrelap->r_offset = *r_offsetp;
+ mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelap->r_addend = addend;
+ mrelap++;
+ **mlocpp = 0;
+ } else {
+ mrelp->r_offset = *r_offsetp;
+ mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelp++;
+ **mlocpp = addend;
}
+ (*mlocpp)++;
+ r_offsetp += loc_size;
}
- *mrelpp = mrelp;
- return mlocp;
+ *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
}
@@ -108,11 +85,12 @@ static int do_func(unsigned const reltype)
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
- Elf_Rel * mrel0;
- Elf_Rel * mrelp;
+ void *mrel0;
+ void *mrelp;
- uint_t * mloc0;
- uint_t * mlocp;
+ GElf_Addr *mloc0;
+ GElf_Addr *mlocp;
+ GElf_Sxword r_offset = 0;
unsigned int rel_entsize = 0;
@@ -149,25 +127,28 @@ static int do_func(unsigned const reltype)
: ".rel__mcount_loc";
/* add section: __mcount_loc */
- mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), _size, 0);
+ mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
if (!mlocs)
goto out;
mlocs->sh.sh_link = 0;
mlocs->sh.sh_info = 0;
- mlocs->sh.sh_addralign = _size;
+ mlocs->sh.sh_addralign = 8;
+ mlocs->data->d_buf = mloc0;
+ mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
/* add section .rel[a]__mcount_loc */
mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
if (!mrels)
goto out;
- mrels->sh.sh_type = is_rela
- ? SHT_RELA
- : SHT_REL;
+ /* Like elf_create_rela_section() without the name bits */
+ mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
mrels->sh.sh_flags = 0;
mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
mrels->sh.sh_info = old_shnum;
- mrels->sh.sh_addralign = _size;
+ mrels->sh.sh_addralign = 8;
+ mrels->data->d_buf = mrel0;
+ mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
list_for_each_entry(sec, &lf->sections, list) {
char const *txtname;
@@ -181,9 +162,8 @@ static int do_func(unsigned const reltype)
txtname, &recval, &recsym))
goto out;
- mlocp = sift_rel_mcount(mlocp,
- (void *)mlocp - (void *)mloc0, &mrelp,
- sec, recsym, (uint_t)recval, reltype);
+ sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
+ recsym, recval, reltype, is_rela);
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
/*
* This section is ignored by ftrace, but still
@@ -195,16 +175,14 @@ static int do_func(unsigned const reltype)
}
if (mloc0 != mlocp) {
- /* Update the section sizes */
+ /* Update the section size and Elf_Data size */
mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
mlocs->len = mlocs->sh.sh_size;
mlocs->data->d_size = mlocs->len;
- mlocs->data->d_buf = mloc0;
- mrels->sh.sh_size = (void *)mrelp - (void *)mrel0;
+ mrels->sh.sh_size = mrelp - mrel0;
mrels->len = mrels->sh.sh_size;
mrels->data->d_size = mrels->len;
- mrels->data->d_buf = mrel0;
/* overwrite the ELF file */
result = elf_write(lf);
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (26 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
` (3 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Now that this function no longer uses any of the old recordmcount
wrapper code we can move it out of the wrapper too.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 47 +++++++++++++++++++++++++++++++++
tools/objtool/recordmcount.h | 50 ------------------------------------
2 files changed, 47 insertions(+), 50 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index ef3c360a3db9..601be2504666 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -394,6 +394,53 @@ static int mcount_adjust = 0;
/* Size of an entry in __mcount_loc; 4 or 8 */
static size_t loc_size;
+/*
+ * Look at the relocations in order to find the calls to mcount.
+ * Accumulate the section offsets that are found, and their relocation info,
+ * onto the end of the existing arrays.
+ */
+static void sift_rel_mcount(GElf_Addr **mlocpp,
+ GElf_Sxword *r_offsetp,
+ void **const mrelpp,
+ const struct section * const rels,
+ unsigned const recsym_index,
+ unsigned long const recval,
+ unsigned const reltype,
+ bool is_rela)
+{
+ GElf_Rel *mrelp = *mrelpp;
+ GElf_Rela *mrelap = *mrelpp;
+ unsigned int mcount_sym_info = 0;
+ struct reloc *reloc;
+
+ list_for_each_entry(reloc, &rels->reloc_list, list) {
+ unsigned long addend;
+
+ if (!mcount_sym_info)
+ mcount_sym_info = get_mcount_sym_info(reloc);
+
+ if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
+ continue;
+
+ addend = reloc->offset - recval + mcount_adjust;
+ if (is_rela) {
+ mrelap->r_offset = *r_offsetp;
+ mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelap->r_addend = addend;
+ mrelap++;
+ **mlocpp = 0;
+ } else {
+ mrelp->r_offset = *r_offsetp;
+ mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
+ mrelp++;
+ **mlocpp = addend;
+ }
+ (*mlocpp)++;
+ r_offsetp += loc_size;
+ }
+ *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
+}
+
/* 32 bit and 64 bit are very similar */
#include "recordmcount.h"
#define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index b58f0cc58f76..f12189331e27 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -17,67 +17,17 @@
* This conversion to macros was done by:
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
-#undef sift_rel_mcount
#undef do_func
#undef Elf_Rela
#ifdef RECORD_MCOUNT_64
-# define sift_rel_mcount sift64_rel_mcount
# define do_func do64
# define Elf_Rela Elf64_Rela
#else
-# define sift_rel_mcount sift32_rel_mcount
# define do_func do32
# define Elf_Rela Elf32_Rela
#endif
-/*
- * Look at the relocations in order to find the calls to mcount.
- * Accumulate the section offsets that are found, and their relocation info,
- * onto the end of the existing arrays.
- */
-static void sift_rel_mcount(GElf_Addr **mlocpp,
- GElf_Sxword *r_offsetp,
- void **const mrelpp,
- const struct section * const rels,
- unsigned const recsym_index,
- unsigned long const recval,
- unsigned const reltype,
- bool is_rela)
-{
- GElf_Rel *mrelp = *mrelpp;
- GElf_Rela *mrelap = *mrelpp;
- unsigned int mcount_sym_info = 0;
- struct reloc *reloc;
-
- list_for_each_entry(reloc, &rels->reloc_list, list) {
- unsigned long addend;
-
- if (!mcount_sym_info)
- mcount_sym_info = get_mcount_sym_info(reloc);
-
- if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
- continue;
-
- addend = reloc->offset - recval + mcount_adjust;
- if (is_rela) {
- mrelap->r_offset = *r_offsetp;
- mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
- mrelap->r_addend = addend;
- mrelap++;
- **mlocpp = 0;
- } else {
- mrelp->r_offset = *r_offsetp;
- mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
- mrelp++;
- **mlocpp = addend;
- }
- (*mlocpp)++;
- r_offsetp += loc_size;
- }
- *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
-}
-
/* Overall supervision for Elf32 ET_REL file. */
static int do_func(unsigned const reltype)
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (27 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick Matt Helsley
` (2 subsequent siblings)
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Remove the last use of the Elf_Rela wrapper by passing the
size of the relocations we're dealing with as a parameter.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 4 ++--
tools/objtool/recordmcount.h | 7 ++-----
2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 601be2504666..096507829b0c 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -574,7 +574,7 @@ static int do_file(char const *const fname)
is_fake_mcount = MIPS_is_fake_mcount;
}
loc_size = 4;
- rc = do32(reltype);
+ rc = do32(reltype, sizeof(Elf32_Rela));
break;
case ELFCLASS64: {
if (lf->ehdr.e_ehsize != sizeof(Elf64_Ehdr)
@@ -592,7 +592,7 @@ static int do_file(char const *const fname)
is_fake_mcount = MIPS_is_fake_mcount;
}
loc_size = 8;
- rc = do64(reltype);
+ rc = do64(reltype, sizeof(Elf64_Rela));
break;
}
} /* end switch */
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index f12189331e27..50104d52d9bf 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -18,19 +18,16 @@
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
#undef do_func
-#undef Elf_Rela
#ifdef RECORD_MCOUNT_64
# define do_func do64
-# define Elf_Rela Elf64_Rela
#else
# define do_func do32
-# define Elf_Rela Elf32_Rela
#endif
/* Overall supervision for Elf32 ET_REL file. */
-static int do_func(unsigned const reltype)
+static int do_func(unsigned const reltype, size_t rela_size)
{
/* Upper bound on space: assume all relevant relocs are for mcount. */
unsigned totrelsz;
@@ -71,7 +68,7 @@ static int do_func(unsigned const reltype)
return -1;
}
- is_rela = (sizeof(Elf_Rela) == rel_entsize);
+ is_rela = (rela_size == rel_entsize);
mc_name = is_rela
? ".rela__mcount_loc"
: ".rel__mcount_loc";
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (28 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 32/32] objtool: mcount: Rename Matt Helsley
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
We no longer need to double-include the recordmcount.h wrapper
All of the types and functions that rely on them have been converted
to using objtool's ELF code. This moves the remaining function to
recordmcount.c and changes the function name to something slightly
more descriptive while dropping the wrapped naming.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 122 ++++++++++++++++++++++++++++--
tools/objtool/recordmcount.h | 142 -----------------------------------
2 files changed, 116 insertions(+), 148 deletions(-)
delete mode 100644 tools/objtool/recordmcount.h
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 096507829b0c..6980c0a8bdc3 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -441,10 +441,120 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
*mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
}
-/* 32 bit and 64 bit are very similar */
-#include "recordmcount.h"
-#define RECORD_MCOUNT_64
-#include "recordmcount.h"
+/* Overall supervision for Elf32 ET_REL file. */
+static int do_mcount(unsigned const reltype, size_t rela_size)
+{
+ /* Upper bound on space: assume all relevant relocs are for mcount. */
+ unsigned totrelsz;
+
+ void *mrel0;
+ void *mrelp;
+
+ GElf_Addr *mloc0;
+ GElf_Addr *mlocp;
+ GElf_Sxword r_offset; /* Used in the added relocations */
+
+ unsigned int rel_entsize = 0;
+
+ struct section *sec, *mlocs, *mrels;
+ unsigned int const old_shnum = lf->ehdr.e_shnum;
+
+ int result = -1;
+ char const *mc_name;
+ bool is_rela;
+
+ if (find_section_by_name(lf, "__mcount_loc") != NULL)
+ return 0;
+
+ totrelsz = tot_relsize(&rel_entsize);
+ if (totrelsz == 0)
+ return 0;
+
+ mrel0 = malloc(totrelsz);
+ mrelp = mrel0;
+ if (!mrel0)
+ return -1;
+
+ /* 2*sizeof(address) <= sizeof(Elf_Rel) */
+ mloc0 = malloc(totrelsz>>1);
+ mlocp = mloc0;
+ if (!mloc0) {
+ free(mrel0);
+ return -1;
+ }
+
+ is_rela = (rela_size == rel_entsize);
+ mc_name = is_rela
+ ? ".rela__mcount_loc"
+ : ".rel__mcount_loc";
+
+ /* add section: __mcount_loc */
+ mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
+ if (!mlocs)
+ goto out;
+
+ mlocs->sh.sh_link = 0;
+ mlocs->sh.sh_info = 0;
+ mlocs->sh.sh_addralign = 8;
+ mlocs->data->d_buf = mloc0;
+ mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
+
+ /* add section .rel[a]__mcount_loc */
+ mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
+ if (!mrels)
+ goto out;
+ /* Like elf_create_rela_section() without the name bits */
+ mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
+ mrels->sh.sh_flags = 0;
+ mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
+ mrels->sh.sh_info = old_shnum;
+ mrels->sh.sh_addralign = 8;
+ mrels->data->d_buf = mrel0;
+ mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
+
+ list_for_each_entry(sec, &lf->sections, list) {
+ char const *txtname;
+
+ txtname = has_rel_mcount(sec);
+ if (txtname && is_mcounted_section_name(txtname)) {
+ unsigned long recval = 0;
+ unsigned int recsym;
+
+ if (find_section_sym_index(sec->sh.sh_info,
+ txtname, &recval, &recsym))
+ goto out;
+
+ sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
+ recsym, recval, reltype, is_rela);
+ } else if (txtname && (warn_on_notrace_sect || make_nop)) {
+ /*
+ * This section is ignored by ftrace, but still
+ * has mcount calls. Convert them to nops now.
+ */
+ if (nop_mcount(sec, txtname) < 0)
+ goto out;
+ }
+ }
+
+ if (mloc0 != mlocp) {
+ /* Update the section size and Elf_Data size */
+ mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
+ mlocs->len = mlocs->sh.sh_size;
+ mlocs->data->d_size = mlocs->len;
+
+ mrels->sh.sh_size = mrelp - mrel0;
+ mrels->len = mrels->sh.sh_size;
+ mrels->data->d_size = mrels->len;
+
+ /* overwrite the ELF file */
+ result = elf_write(lf);
+ } else
+ result = 0;
+out:
+ free(mrel0);
+ free(mloc0);
+ return result;
+}
static int arm_is_fake_mcount(struct reloc const *rp)
{
@@ -574,7 +684,7 @@ static int do_file(char const *const fname)
is_fake_mcount = MIPS_is_fake_mcount;
}
loc_size = 4;
- rc = do32(reltype, sizeof(Elf32_Rela));
+ rc = do_mcount(reltype, sizeof(Elf32_Rela));
break;
case ELFCLASS64: {
if (lf->ehdr.e_ehsize != sizeof(Elf64_Ehdr)
@@ -592,7 +702,7 @@ static int do_file(char const *const fname)
is_fake_mcount = MIPS_is_fake_mcount;
}
loc_size = 8;
- rc = do64(reltype, sizeof(Elf64_Rela));
+ rc = do_mcount(reltype, sizeof(Elf64_Rela));
break;
}
} /* end switch */
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
deleted file mode 100644
index 50104d52d9bf..000000000000
--- a/tools/objtool/recordmcount.h
+++ /dev/null
@@ -1,142 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * recordmcount.h
- *
- * This code was taken out of recordmcount.c written by
- * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
- *
- * The original code had the same algorithms for both 32bit
- * and 64bit ELF files, but the code was duplicated to support
- * the difference in structures that were used. This
- * file creates a macro of everything that is different between
- * the 64 and 32 bit code, such that by including this header
- * twice we can create both sets of functions by including this
- * header once with RECORD_MCOUNT_64 undefined, and again with
- * it defined.
- *
- * This conversion to macros was done by:
- * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
- */
-#undef do_func
-
-#ifdef RECORD_MCOUNT_64
-# define do_func do64
-#else
-# define do_func do32
-#endif
-
-
-/* Overall supervision for Elf32 ET_REL file. */
-static int do_func(unsigned const reltype, size_t rela_size)
-{
- /* Upper bound on space: assume all relevant relocs are for mcount. */
- unsigned totrelsz;
-
- void *mrel0;
- void *mrelp;
-
- GElf_Addr *mloc0;
- GElf_Addr *mlocp;
- GElf_Sxword r_offset = 0;
-
- unsigned int rel_entsize = 0;
-
- struct section *sec, *mlocs, *mrels;
- unsigned int const old_shnum = lf->ehdr.e_shnum;
-
- int result = -1;
- char const *mc_name;
- bool is_rela;
-
- if (find_section_by_name(lf, "__mcount_loc") != NULL)
- return 0;
-
- totrelsz = tot_relsize(&rel_entsize);
- if (totrelsz == 0)
- return 0;
-
- mrel0 = malloc(totrelsz);
- mrelp = mrel0;
- if (!mrel0)
- return -1;
-
- /* 2*sizeof(address) <= sizeof(Elf_Rel) */
- mloc0 = malloc(totrelsz>>1);
- mlocp = mloc0;
- if (!mloc0) {
- free(mrel0);
- return -1;
- }
-
- is_rela = (rela_size == rel_entsize);
- mc_name = is_rela
- ? ".rela__mcount_loc"
- : ".rel__mcount_loc";
-
- /* add section: __mcount_loc */
- mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
- if (!mlocs)
- goto out;
-
- mlocs->sh.sh_link = 0;
- mlocs->sh.sh_info = 0;
- mlocs->sh.sh_addralign = 8;
- mlocs->data->d_buf = mloc0;
- mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
-
- /* add section .rel[a]__mcount_loc */
- mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
- if (!mrels)
- goto out;
- /* Like elf_create_rela_section() without the name bits */
- mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
- mrels->sh.sh_flags = 0;
- mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
- mrels->sh.sh_info = old_shnum;
- mrels->sh.sh_addralign = 8;
- mrels->data->d_buf = mrel0;
- mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
-
- list_for_each_entry(sec, &lf->sections, list) {
- char const *txtname;
-
- txtname = has_rel_mcount(sec);
- if (txtname && is_mcounted_section_name(txtname)) {
- unsigned long recval = 0;
- unsigned int recsym;
-
- if (find_section_sym_index(sec->sh.sh_info,
- txtname, &recval, &recsym))
- goto out;
-
- sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
- recsym, recval, reltype, is_rela);
- } else if (txtname && (warn_on_notrace_sect || make_nop)) {
- /*
- * This section is ignored by ftrace, but still
- * has mcount calls. Convert them to nops now.
- */
- if (nop_mcount(sec, txtname) < 0)
- goto out;
- }
- }
-
- if (mloc0 != mlocp) {
- /* Update the section size and Elf_Data size */
- mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
- mlocs->len = mlocs->sh.sh_size;
- mlocs->data->d_size = mlocs->len;
-
- mrels->sh.sh_size = mrelp - mrel0;
- mrels->len = mrels->sh.sh_size;
- mrels->data->d_size = mrels->len;
-
- /* overwrite the ELF file */
- result = elf_write(lf);
- } else
- result = 0;
-out:
- free(mrel0);
- free(mloc0);
- return result;
-}
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (29 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 32/32] objtool: mcount: Rename Matt Helsley
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Now that they're no longer used we can remove these endian
wrappers.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/recordmcount.c | 63 ------------------------------------
1 file changed, 63 deletions(-)
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 6980c0a8bdc3..aa2f6a64bff0 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -149,53 +149,6 @@ static int make_nop_arm64(struct section *txts, size_t const offset)
return 0;
}
-/* w8rev, w8nat, ...: Handle endianness. */
-
-static uint64_t w8rev(uint64_t const x)
-{
- return ((0xff & (x >> (0 * 8))) << (7 * 8))
- | ((0xff & (x >> (1 * 8))) << (6 * 8))
- | ((0xff & (x >> (2 * 8))) << (5 * 8))
- | ((0xff & (x >> (3 * 8))) << (4 * 8))
- | ((0xff & (x >> (4 * 8))) << (3 * 8))
- | ((0xff & (x >> (5 * 8))) << (2 * 8))
- | ((0xff & (x >> (6 * 8))) << (1 * 8))
- | ((0xff & (x >> (7 * 8))) << (0 * 8));
-}
-
-static uint32_t w4rev(uint32_t const x)
-{
- return ((0xff & (x >> (0 * 8))) << (3 * 8))
- | ((0xff & (x >> (1 * 8))) << (2 * 8))
- | ((0xff & (x >> (2 * 8))) << (1 * 8))
- | ((0xff & (x >> (3 * 8))) << (0 * 8));
-}
-
-static uint32_t w2rev(uint16_t const x)
-{
- return ((0xff & (x >> (0 * 8))) << (1 * 8))
- | ((0xff & (x >> (1 * 8))) << (0 * 8));
-}
-
-static uint64_t w8nat(uint64_t const x)
-{
- return x;
-}
-
-static uint32_t w4nat(uint32_t const x)
-{
- return x;
-}
-
-static uint32_t w2nat(uint16_t const x)
-{
- return x;
-}
-
-static uint64_t (*w8)(uint64_t);
-static uint32_t (*w)(uint32_t);
-static uint32_t (*w2)(uint16_t);
-
/* Names of the sections that could contain calls to mcount. */
static int is_mcounted_section_name(char const *const txtname)
{
@@ -579,22 +532,12 @@ static int do_file(char const *const fname)
goto out;
}
- w = w4nat;
- w2 = w2nat;
- w8 = w8nat;
switch (lf->ehdr.e_ident[EI_DATA]) {
- static unsigned int const endian = 1;
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
lf->ehdr.e_ident[EI_DATA], fname);
goto out;
case ELFDATA2LSB:
- if (*(unsigned char const *)&endian != 1) {
- /* objtool is big endian, file.o is little endian. */
- w = w4rev;
- w2 = w2rev;
- w8 = w8rev;
- }
ideal_nop4_arm = ideal_nop4_arm_le;
bl_mcount_arm = bl_mcount_arm_le;
push_arm = push_arm_le;
@@ -602,12 +545,6 @@ static int do_file(char const *const fname)
push_bl_mcount_thumb = push_bl_mcount_thumb_le;
break;
case ELFDATA2MSB:
- if (*(unsigned char const *)&endian != 0) {
- /* objtool is little endian, file.o is big endian. */
- w = w4rev;
- w2 = w2rev;
- w8 = w8rev;
- }
ideal_nop4_arm = ideal_nop4_arm_be;
bl_mcount_arm = bl_mcount_arm_be;
push_arm = push_arm_be;
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* [RFC][PATCH v4 32/32] objtool: mcount: Rename
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
` (30 preceding siblings ...)
2020-06-02 19:50 ` [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers Matt Helsley
@ 2020-06-02 19:50 ` Matt Helsley
31 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-02 19:50 UTC (permalink / raw)
To: linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal, Matt Helsley
Now that we've converted recordmcount to a subcommand of objtool
rename the .c file in order to follow the convention of the other
objtool subcmds.
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
tools/objtool/Build | 2 +-
tools/objtool/{recordmcount.c => mcount.c} | 0
2 files changed, 1 insertion(+), 1 deletion(-)
rename tools/objtool/{recordmcount.c => mcount.c} (100%)
diff --git a/tools/objtool/Build b/tools/objtool/Build
index f4f0515d4f91..7815a094c991 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -7,7 +7,7 @@ objtool-$(SUBCMD_CHECK) += special.o
objtool-$(SUBCMD_ORC) += check.o
objtool-$(SUBCMD_ORC) += orc_gen.o
objtool-$(SUBCMD_ORC) += orc_dump.o
-objtool-$(SUBCMD_MCOUNT) += recordmcount.o
+objtool-$(SUBCMD_MCOUNT) += mcount.o
objtool-y += builtin-check.o
objtool-y += builtin-orc.o
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/mcount.c
similarity index 100%
rename from tools/objtool/recordmcount.c
rename to tools/objtool/mcount.c
--
2.20.1
^ permalink raw reply related [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
@ 2020-06-09 6:41 ` Kamalesh Babulal
2020-06-09 18:12 ` Matt Helsley
0 siblings, 1 reply; 49+ messages in thread
From: Kamalesh Babulal @ 2020-06-09 6:41 UTC (permalink / raw)
To: Matt Helsley
Cc: linux-kernel, Josh Poimboeuf, Peter Zijlstra, Steven Rostedt,
Sami Tolvanen, Julien Thierry
On 6/3/20 1:20 AM, Matt Helsley wrote:
> Rather than building the exact ELF section data we need and
> avoiding libelf's conversion step, use more GElf types
> and then libelf's elfxx_xlatetof() functions to convert
> the mcount locations (GElf_Addr) and associated relocations.
>
> This converts sift_rel_mcount() so that it doesn't use the
> recordmcount wrapper. The next patch will move it out of the
> wrapper.
>
> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> ---
> tools/objtool/recordmcount.c | 44 +++----------
> tools/objtool/recordmcount.h | 120 ++++++++++++++---------------------
> 2 files changed, 59 insertions(+), 105 deletions(-)
>
> diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
> index 06a8f8ddefa7..ef3c360a3db9 100644
> --- a/tools/objtool/recordmcount.c
> +++ b/tools/objtool/recordmcount.c
[...]
> -static uint_t *sift_rel_mcount(uint_t *mlocp,
> - unsigned const offbase,
> - Elf_Rel **const mrelpp,
> +static void sift_rel_mcount(GElf_Addr **mlocpp,
> + GElf_Sxword *r_offsetp,
> + void **const mrelpp,
> const struct section * const rels,
> unsigned const recsym_index,
> unsigned long const recval,
> - unsigned const reltype)
> + unsigned const reltype,
> + bool is_rela)
> {
> - uint_t *const mloc0 = mlocp;
> - Elf_Rel *mrelp = *mrelpp;
> - unsigned int rel_entsize = rels->sh.sh_entsize;
> - unsigned mcountsym = 0;
> + GElf_Rel *mrelp = *mrelpp;
> + GElf_Rela *mrelap = *mrelpp;
> + unsigned int mcount_sym_info = 0;
> struct reloc *reloc;
>
> list_for_each_entry(reloc, &rels->reloc_list, list) {
> - if (!mcountsym)
> - mcountsym = get_mcountsym(reloc);
> -
> - if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
> - uint_t const addend =
> - _w(reloc->offset - recval + mcount_adjust);
> - mrelp->r_offset = _w(offbase
> - + ((void *)mlocp - (void *)mloc0));
> - Elf_r_info(mrelp, recsym_index, reltype);
> - if (rel_entsize == sizeof(Elf_Rela)) {
> - ((Elf_Rela *)mrelp)->r_addend = addend;
> - *mlocp++ = 0;
> - } else
> - *mlocp++ = addend;
> -
> - mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
> + unsigned long addend;
> +
> + if (!mcount_sym_info)
> + mcount_sym_info = get_mcount_sym_info(reloc);
> +
> + if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
> + continue;
Hi Matt,
I was trying out the patch series on ppc64le and found that __mcount_loc
and .rela__mcount_loc section pairs do not get generated.
# readelf -S fs/proc/cmdline.o|grep mcount
#
Debugged the cause to get_mcountsym()'s return type. It returns reloc
type from GELF_R_INFO() and expects Elf64_Xword a.k.a unsigned long
to be the return type but get_mcountsym() returns unsigned int on 64-bit.
On power the _mcount is of relocation type R_PPC64_REL24 (info 0x170000000a),
using unsigned int truncates the value to 0xa and fails the above check.
Using below fix, that converts mcount_sym_info to use unsigned long, generates
the __mcount_loc section pairs.
--- a/tools/objtool/mcount.c
+++ b/tools/objtool/mcount.c
@@ -163,7 +163,7 @@ static int is_mcounted_section_name(char const *const txtname)
strcmp(".cpuidle.text", txtname) == 0;
}
-static unsigned int get_mcount_sym_info(struct reloc *reloc)
+static unsigned long get_mcount_sym_info(struct reloc *reloc)
{
struct symbol *sym = reloc->sym;
char const *symname = sym->name;
@@ -274,7 +274,7 @@ static int nop_mcount(struct section * const rels,
{
struct reloc *reloc;
struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
- unsigned int mcount_sym_info = 0;
+ unsigned long mcount_sym_info = 0;
int once = 0;
list_for_each_entry(reloc, &rels->reloc_list, list) {
@@ -363,7 +363,7 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
{
GElf_Rel *mrelp = *mrelpp;
GElf_Rela *mrelap = *mrelpp;
- unsigned int mcount_sym_info = 0;
+ unsigned long mcount_sym_info = 0;
struct reloc *reloc;
list_for_each_entry(reloc, &rels->reloc_list, list) {
# readelf -S fs/proc/cmdline.o|grep mcount
[31] __mcount_loc PROGBITS 0000000000000000 00022f10
[32] .rela__mcount_loc RELA 0000000000000000 00022f20
> +
> + addend = reloc->offset - recval + mcount_adjust;
> + if (is_rela) {
> + mrelap->r_offset = *r_offsetp;
> + mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
> + mrelap->r_addend = addend;
> + mrelap++;
> + **mlocpp = 0;
> + } else {
> + mrelp->r_offset = *r_offsetp;
> + mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
> + mrelp++;
> + **mlocpp = addend;
> }
> + (*mlocpp)++;
> + r_offsetp += loc_size;
the offsets generated for rela__mcount_loc section are incorrect:
# readelf -rW fs/proc/meminfo.o
[...]
Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries:
Offset Info Type Symbol's Value Symbol's Name + Addend
0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c
00000a059c401f38 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64
0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c
0000000000000000 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c
changing the above line to *r_offsetp += loc_size and initializing
r_offset=0 in do_mcount() generates the correct offset:
# readelf -rW fs/proc/meminfo.o
[...]
Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries:
Offset Info Type Symbol's Value Symbol's Name + Addend
0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c
0000000000000008 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64
0000000000000010 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c
0000000000000018 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c
> }
> - *mrelpp = mrelp;
> - return mlocp;
> + *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
> }
>
>
--
Kamalesh
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
@ 2020-06-09 8:54 ` Julien Thierry
2020-06-09 15:42 ` Matt Helsley
0 siblings, 1 reply; 49+ messages in thread
From: Julien Thierry @ 2020-06-09 8:54 UTC (permalink / raw)
To: Matt Helsley, linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Kamalesh Babulal
Hi Matt,
On 6/2/20 8:49 PM, Matt Helsley wrote:
> Move recordmcount into the objtool directory. We keep this step separate
> so changes which turn recordmcount into a subcommand of objtool don't
> get obscured.
>
> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> ---
> Documentation/trace/ftrace-design.rst | 4 ++--
> Documentation/trace/ftrace.rst | 2 +-
> Makefile | 15 +++++++++------
> scripts/.gitignore | 1 -
> scripts/Makefile | 1 -
> scripts/Makefile.build | 11 ++++++-----
> tools/objtool/.gitignore | 1 +
> tools/objtool/Build | 2 ++
> tools/objtool/Makefile | 13 ++++++++++++-
> {scripts => tools/objtool}/recordmcount.c | 0
> {scripts => tools/objtool}/recordmcount.h | 0
> {scripts => tools/objtool}/recordmcount.pl | 0
> 12 files changed, 33 insertions(+), 17 deletions(-)
> rename {scripts => tools/objtool}/recordmcount.c (100%)
> rename {scripts => tools/objtool}/recordmcount.h (100%)
> rename {scripts => tools/objtool}/recordmcount.pl (100%)
>
> diff --git a/Documentation/trace/ftrace-design.rst b/Documentation/trace/ftrace-design.rst
> index a8e22e0db63c..dea8db5e79d0 100644
> --- a/Documentation/trace/ftrace-design.rst
> +++ b/Documentation/trace/ftrace-design.rst
> @@ -261,7 +261,7 @@ You need very few things to get the syscalls tracing in an arch.
> HAVE_FTRACE_MCOUNT_RECORD
> -------------------------
>
> -See scripts/recordmcount.pl for more info. Just fill in the arch-specific
> +See tools/objtool/recordmcount.pl for more info. Just fill in the arch-specific
> details for how to locate the addresses of mcount call sites via objdump.
> This option doesn't make much sense without also implementing dynamic ftrace.
>
> @@ -379,7 +379,7 @@ linux/ftrace.h for the functions::
> ftrace_make_call()
>
> The rec->ip value is the address of the mcount call site that was collected
> -by the scripts/recordmcount.pl during build time.
> +by the tools/objtool/recordmcount.pl during build time.
>
> The last function is used to do runtime patching of the active tracer. This
> will be modifying the assembly code at the location of the ftrace_call symbol
> diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
> index 3b5614b1d1a5..9adefcc3c7a8 100644
> --- a/Documentation/trace/ftrace.rst
> +++ b/Documentation/trace/ftrace.rst
> @@ -2685,7 +2685,7 @@ starts of pointing to a simple return. (Enabling FTRACE will
> include the -pg switch in the compiling of the kernel.)
>
> At compile time every C file object is run through the
> -recordmcount program (located in the scripts directory). This
> +recordmcount program (located in the tools/objtool directory). This
> program will parse the ELF headers in the C object to find all
> the locations in the .text section that call mcount. Starting
> with gcc version 4.6, the -mfentry has been added for x86, which
> diff --git a/Makefile b/Makefile
> index 04f5662ae61a..d353a0a65a71 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -844,6 +844,7 @@ ifdef CONFIG_DYNAMIC_FTRACE
> ifdef CONFIG_HAVE_C_RECORDMCOUNT
> BUILD_C_RECORDMCOUNT := y
> export BUILD_C_RECORDMCOUNT
> + objtool_target := tools/objtool FORCE
> endif
> endif
> endif
> @@ -1023,10 +1024,10 @@ endif
> export mod_sign_cmd
>
> HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
> +has_libelf := $(call try-run,\
> + echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
>
Maybe there could be some build dependency, e.g. CONFIG_OBJTOOL_SUBCMDS
that sets the "objtool_target" and "has_libelf" when selected.
Then the CONFIG_UNWINDER_ORC, RECORD_MCOUNT and STACK_VALIDATION would
just had to select that config option.
> ifdef CONFIG_STACK_VALIDATION
> - has_libelf := $(call try-run,\
> - echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
> ifeq ($(has_libelf),1)
> objtool_target := tools/objtool FORCE
> else
> @@ -1163,13 +1164,15 @@ uapi-asm-generic:
>
> PHONY += prepare-objtool
> prepare-objtool: $(objtool_target)
> -ifeq ($(SKIP_STACK_VALIDATION),1)
> -ifdef CONFIG_UNWINDER_ORC
> +ifneq ($(has_libelf),1)
> + ifdef CONFIG_UNWINDER_ORC
> @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
> @false
> -else
> + else
> + ifeq ($(SKIP_STACK_VALIDATION),1)
> @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
I think this would be more readable without the else branch:
ifneq ($(has_libelf),1)
ifdef <some objtool command config>
<warn about unavailability>
endif
ifdef <another objtool command config>
<warn ...>
endif
<...>
endif
Cheers,
--
Julien Thierry
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
@ 2020-06-09 9:00 ` Julien Thierry
2020-06-09 18:39 ` Matt Helsley
0 siblings, 1 reply; 49+ messages in thread
From: Julien Thierry @ 2020-06-09 9:00 UTC (permalink / raw)
To: Matt Helsley, linux-kernel
Cc: Josh Poimboeuf, Peter Zijlstra, Steven Rostedt, Sami Tolvanen,
Kamalesh Babulal
Hi Matt,
On 6/2/20 8:49 PM, Matt Helsley wrote:
> Rather than a standalone executable merge recordmcount as a sub command
> of objtool. This is a small step towards cleaning up recordmcount and
> eventually sharing ELF code with objtool.
>
> For the initial step all that's required is a bit of Makefile changes
> and invoking the former main() function from recordmcount.c because the
> subcommand code uses similar function arguments as main when dispatching.
>
> objtool ignores some object files that tracing does not, specifically
> those with OBJECT_FILES_NON_STANDARD Makefile variables. For this reason
> we keep the recordmcount_dep separate from the objtool_dep. When using
> objtool mcount we can also, like the other objtool invocations, just
> depend on the binary rather than the source the binary is built from.
>
> Subsequent patches will gradually convert recordmcount to use
> more and more of libelf/objtool's ELF accessor code. This will both
> clean up recordmcount to be more easily readable and remove
> recordmcount's crude accessor wrapping code.
>
> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> ---
> Documentation/dontdiff | 2 +-
> Documentation/trace/ftrace.rst | 6 ++--
> Makefile | 9 ++++--
> arch/arm64/include/asm/ftrace.h | 2 +-
> arch/x86/include/asm/ftrace.h | 2 +-
> kernel/trace/Kconfig | 2 +-
> scripts/Makefile.build | 19 +++++++------
> scripts/sorttable.h | 2 +-
> tools/objtool/Build | 4 +--
> tools/objtool/Makefile | 48 +++++++++++++++++++++++--------
> tools/objtool/builtin-mcount.c | 50 +++++++++++++++++++++++++++++++++
> tools/objtool/builtin.h | 2 ++
> tools/objtool/objtool.c | 1 +
> tools/objtool/objtool.h | 1 +
> tools/objtool/recordmcount.c | 36 +++++++-----------------
> tools/objtool/weak.c | 5 ++++
> 16 files changed, 131 insertions(+), 60 deletions(-)
> create mode 100644 tools/objtool/builtin-mcount.c
>
> diff --git a/Documentation/dontdiff b/Documentation/dontdiff
> index 72fc2e9e2b63..d7e0ec691e02 100644
> --- a/Documentation/dontdiff
> +++ b/Documentation/dontdiff
> @@ -211,7 +211,7 @@ r420_reg_safe.h
> r600_reg_safe.h
> randomize_layout_hash.h
> randomize_layout_seed.h
> -recordmcount
> +objtool
> relocs
> rlim_names.h
> rn50_reg_safe.h
> diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
> index 9adefcc3c7a8..6b9fc7cad543 100644
> --- a/Documentation/trace/ftrace.rst
> +++ b/Documentation/trace/ftrace.rst
> @@ -2684,8 +2684,8 @@ every kernel function, produced by the -pg switch in gcc),
> starts of pointing to a simple return. (Enabling FTRACE will
> include the -pg switch in the compiling of the kernel.)
>
> -At compile time every C file object is run through the
> -recordmcount program (located in the tools/objtool directory). This
> +At compile time every C file object is run through objtool's
> +mcount subcommand (located in the tools/objtool directory). This
> program will parse the ELF headers in the C object to find all
> the locations in the .text section that call mcount. Starting
> with gcc version 4.6, the -mfentry has been added for x86, which
> @@ -2699,7 +2699,7 @@ can be traced.
>
> A section called "__mcount_loc" is created that holds
> references to all the mcount/fentry call sites in the .text section.
> -The recordmcount program re-links this section back into the
> +Running "objtool mcount" re-links this section back into the
> original object. The final linking stage of the kernel will add all these
> references into a single table.
>
> diff --git a/Makefile b/Makefile
> index d353a0a65a71..99a4d8c61bdb 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -842,12 +842,12 @@ KBUILD_CFLAGS += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
> KBUILD_AFLAGS += $(CC_FLAGS_USING)
> ifdef CONFIG_DYNAMIC_FTRACE
> ifdef CONFIG_HAVE_C_RECORDMCOUNT
> - BUILD_C_RECORDMCOUNT := y
> - export BUILD_C_RECORDMCOUNT
> + USE_OBJTOOL_MCOUNT := y
> + export USE_OBJTOOL_MCOUNT
> objtool_target := tools/objtool FORCE
> endif
> endif
> -endif
> +endif # CONFIG_FUNCTION_TRACER
>
> # We trigger additional mismatches with less inlining
> ifdef CONFIG_DEBUG_SECTION_MISMATCH
> @@ -1168,6 +1168,9 @@ ifneq ($(has_libelf),1)
> ifdef CONFIG_UNWINDER_ORC
> @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
> @false
> + else ifdef USE_OBJTOOL_MCOUNT
> + @echo "error: Cannot generate tracing metadata for CONFIG_DYNAMIC_FTRACE, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
> + @false
> else
> ifeq ($(SKIP_STACK_VALIDATION),1)
> @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
> index 91fa4baa1a93..5fd71bf592d5 100644
> --- a/arch/arm64/include/asm/ftrace.h
> +++ b/arch/arm64/include/asm/ftrace.h
> @@ -62,7 +62,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
> return addr + AARCH64_INSN_SIZE;
> /*
> * addr is the address of the mcount call instruction.
> - * recordmcount does the necessary offset calculation.
> + * "objtool mcount" does the necessary offset calculation.
> */
> return addr;
> }
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index 84b9449be080..c849f3818369 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -23,7 +23,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
> {
> /*
> * addr is the address of the mcount call instruction.
> - * recordmcount does the necessary offset calculation.
> + * "objtool mcount" does the necessary offset calculation.
> */
> return addr;
> }
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 743647005f64..ae74647b06fa 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -59,7 +59,7 @@ config HAVE_NOP_MCOUNT
> config HAVE_C_RECORDMCOUNT
> bool
> help
> - C version of recordmcount available?
> + C version of objtool mcount available?
The "C version" doesn't make much sense here. "Objtool mcount
available?" or "mcount subcommand of objtool available?" perhaps?
>
> config TRACER_MAX_TRACE
> bool
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index d753facdb943..ab0aa6088039 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -163,22 +163,23 @@ endif
>
> ifdef CONFIG_FTRACE_MCOUNT_RECORD
> ifndef CC_USING_RECORD_MCOUNT
> -# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
> -ifdef BUILD_C_RECORDMCOUNT
> +# The compiler does not support generation of the __mcount_loc section.
> +# Generate it manually with "objtool mcount record" or recordmcount.pl
> +ifdef USE_OBJTOOL_MCOUNT
> ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
> RECORDMCOUNT_FLAGS = -w
> endif
> # Due to recursion, we must skip empty.o.
> # The empty.o file is created in the make process in order to determine
> # the target endianness and word size. It is made before all other C
> -# files, including recordmcount.
> +# files, including objtool.
> sub_cmd_record_mcount = \
> if [ $(@) != "scripts/mod/empty.o" ]; then \
> - $(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
> + $(objtree)/tools/objtool/objtool mcount record $(RECORDMCOUNT_FLAGS) "$(@)"; \
> fi;
>
> -recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
> - $(srctree)/tools/objtool/recordmcount.h
> +recordmcount_dep = $(objtree)/tools/objtool/objtool \
> + $(wildcard include/config/ftrace/mcount/record.h)
> else
> sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
> "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
> @@ -186,8 +187,8 @@ sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)"
> "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
> "$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
> "$(if $(part-of-module),1,0)" "$(@)";
> -recordmcount_source := $(srctree)/tools/objtool/recordmcount.pl
> -endif # BUILD_C_RECORDMCOUNT
> +recordmcount_dep = $(srctree)/tools/objtool/recordmcount.pl
> +endif # USE_OBJTOOL_MCOUNT
> cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), \
> $(sub_cmd_record_mcount))
> endif # CC_USING_RECORD_MCOUNT
> @@ -263,7 +264,7 @@ cmd_undef_syms = echo
> endif
>
> # Built-in and composite module parts
> -$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
> +$(obj)/%.o: $(src)/%.c $(recordmcount_dep) $(objtool_dep) FORCE
> $(call cmd,force_checksrc)
> $(call if_changed_rule,cc_o_c)
>
> diff --git a/scripts/sorttable.h b/scripts/sorttable.h
> index a2baa2fefb13..986aa3414cf6 100644
> --- a/scripts/sorttable.h
> +++ b/scripts/sorttable.h
> @@ -11,7 +11,7 @@
> * Some of code was taken out of arch/x86/kernel/unwind_orc.c, written by:
> * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
> *
> - * Some of this code was taken out of recordmcount.h written by:
> + * Some of this code was taken out of objtool mcount written by:
> *
> * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
> * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
> diff --git a/tools/objtool/Build b/tools/objtool/Build
> index 4d399aff76de..f4f0515d4f91 100644
> --- a/tools/objtool/Build
> +++ b/tools/objtool/Build
> @@ -7,9 +7,11 @@ objtool-$(SUBCMD_CHECK) += special.o
> objtool-$(SUBCMD_ORC) += check.o
> objtool-$(SUBCMD_ORC) += orc_gen.o
> objtool-$(SUBCMD_ORC) += orc_dump.o
> +objtool-$(SUBCMD_MCOUNT) += recordmcount.o
>
> objtool-y += builtin-check.o
> objtool-y += builtin-orc.o
> +objtool-y += builtin-mcount.o
> objtool-y += elf.o
> objtool-y += objtool.o
>
> @@ -35,5 +37,3 @@ $(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
> $(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
> $(call rule_mkdir)
> $(call if_changed_dep,cc_o_c)
> -
> -recordmcount-y += recordmcount.o
> diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> index 285474a77fe9..ffef73f7f47e 100644
> --- a/tools/objtool/Makefile
> +++ b/tools/objtool/Makefile
> @@ -31,12 +31,6 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
> LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
> LIBELF_LIBS := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
>
> -RECORDMCOUNT := $(OUTPUT)recordmcount
> -RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
> -ifeq ($(BUILD_C_RECORDMCOUNT),y)
> -all: $(RECORDMCOUNT)
> -endif
> -
> all: $(OBJTOOL)
>
> INCLUDES := -I$(srctree)/tools/include \
> @@ -55,13 +49,47 @@ AWK = awk
>
> SUBCMD_CHECK := n
> SUBCMD_ORC := n
> +SUBCMD_MCOUNT := n
>
> ifeq ($(SRCARCH),x86)
> SUBCMD_CHECK := y
> SUBCMD_ORC := y
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),arm)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),arm64)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),ia64)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),mips)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),powerpc)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),s390)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),sh)
> + SUBCMD_MCOUNT := y
> +endif
> +
> +ifeq ($(SRCARCH),sparc)
> + SUBCMD_MCOUNT := y
Is there some arch for which MCOUNT is not supported? If not you could
just have MCOUNT default to 'y' and avoid adding all those tests (or
maybe reduce the numbers and set to 'n' only for arches not supporting it).
> endif
>
> -export SUBCMD_CHECK SUBCMD_ORC
> +export SUBCMD_CHECK SUBCMD_ORC SUBCMD_MCOUNT
> export srctree OUTPUT CFLAGS SRCARCH AWK
> include $(srctree)/tools/build/Makefile.include
>
> @@ -69,20 +97,16 @@ $(OBJTOOL_IN): fixdep FORCE
> @$(CONFIG_SHELL) ./sync-check.sh
> @$(MAKE) $(build)=objtool
>
> -$(RECORDMCOUNT_IN): fixdep FORCE
> - @$(MAKE) $(build)=recordmcount
>
> $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
> $(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
>
> -$(RECORDMCOUNT): $(RECORDMCOUNT_IN)
> - $(QUIET_LINK)$(CC) $(RECORDMCOUNT_IN) $(KBUILD_HOSTLDFLAGS) -o $@
>
> $(LIBSUBCMD): fixdep FORCE
> $(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
>
> clean:
> - $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) $(RECORDMCOUNT)
> + $(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
> $(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
> $(Q)$(RM) $(OUTPUT)arch/x86/inat-tables.c $(OUTPUT)fixdep
>
> diff --git a/tools/objtool/builtin-mcount.c b/tools/objtool/builtin-mcount.c
> new file mode 100644
> index 000000000000..4ffc105ab7bb
> --- /dev/null
> +++ b/tools/objtool/builtin-mcount.c
> @@ -0,0 +1,50 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +/*
> + * objtool mcount:
> + *
> + * This command analyzes a .o file and constructs a table of the locations of
> + * calls to 'mcount' useful to ftrace. We can optionally append this table to
> + * the object file ("objtool mcount record foo.o") or output it separately
> + * ("objtool mcount show"). The latter can be used to compare the expected
> + * callers of mcount to those actually found.
> + */
> +
> +#include <string.h>
> +#include <subcmd/parse-options.h>
> +#include "builtin.h"
> +#include "objtool.h"
> +
> +static const char * const mcount_usage[] = {
> + "objtool mcount record [<options>] file.o [file2.o ...]",
> + NULL,
> +};
> +
> +bool warn_on_notrace_sect;
> +
> +const static struct option mcount_options[] = {
> + OPT_BOOLEAN('w', "warn-on-notrace-section", &warn_on_notrace_sect,
> + "Emit a warning when a section omitting mcount "
> + "(possibly due to \"notrace\" marking) is encountered"),
> + OPT_END(),
> +};
> +
> +int cmd_mcount(int argc, const char **argv)
> +{
> + argc--; argv++;
> + if (argc <= 0)
> + usage_with_options(mcount_usage, mcount_options);
> +
> + if (!strncmp(argv[0], "record", 6)) {
> + argc = parse_options(argc, argv,
> + mcount_options, mcount_usage, 0);
> + if (argc < 1)
> + usage_with_options(mcount_usage, mcount_options);
> +
> + return record_mcount(argc, argv);
> + }
> +
> + usage_with_options(mcount_usage, mcount_options);
> +
> + return 0;
> +}
> diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
> index 85c979caa367..9c7331592fa7 100644
> --- a/tools/objtool/builtin.h
> +++ b/tools/objtool/builtin.h
> @@ -12,5 +12,7 @@ extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
>
> extern int cmd_check(int argc, const char **argv);
> extern int cmd_orc(int argc, const char **argv);
> +extern bool is_cmd_mcount_available(void);
This appears to be unused.
Cheers,
--
Julien Thierry
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount
2020-06-09 8:54 ` Julien Thierry
@ 2020-06-09 15:42 ` Matt Helsley
2020-06-09 19:31 ` Julien Thierry
0 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-09 15:42 UTC (permalink / raw)
To: Julien Thierry
Cc: linux-kernel, Josh Poimboeuf, Peter Zijlstra, Steven Rostedt,
Sami Tolvanen, Kamalesh Babulal
On Tue, Jun 09, 2020 at 09:54:33AM +0100, Julien Thierry wrote:
> Hi Matt,
>
> On 6/2/20 8:49 PM, Matt Helsley wrote:
> > Move recordmcount into the objtool directory. We keep this step separate
> > so changes which turn recordmcount into a subcommand of objtool don't
> > get obscured.
> >
> > Signed-off-by: Matt Helsley <mhelsley@vmware.com>
<snip>
> > diff --git a/Makefile b/Makefile
> > index 04f5662ae61a..d353a0a65a71 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -844,6 +844,7 @@ ifdef CONFIG_DYNAMIC_FTRACE
> > ifdef CONFIG_HAVE_C_RECORDMCOUNT
> > BUILD_C_RECORDMCOUNT := y
> > export BUILD_C_RECORDMCOUNT
> > + objtool_target := tools/objtool FORCE
> > endif
> > endif
> > endif
> > @@ -1023,10 +1024,10 @@ endif
> > export mod_sign_cmd
> > HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
> > +has_libelf := $(call try-run,\
> > + echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
>
> Maybe there could be some build dependency, e.g. CONFIG_OBJTOOL_SUBCMDS that
> sets the "objtool_target" and "has_libelf" when selected.
>
> Then the CONFIG_UNWINDER_ORC, RECORD_MCOUNT and STACK_VALIDATION would just
> had to select that config option.
That might save a good amount of control flow in the Makefiles.
We could take it one step further and have specific CONFIG_OBJTOOL_<subcmd>
which might help us remove the per-architecture control-flow in
the multi-arch subcmd support found in tools/objtool/Makefile.
What do folks think of that -- too far?
>
> > ifdef CONFIG_STACK_VALIDATION
> > - has_libelf := $(call try-run,\
> > - echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
> > ifeq ($(has_libelf),1)
> > objtool_target := tools/objtool FORCE
> > else
> > @@ -1163,13 +1164,15 @@ uapi-asm-generic:
> > PHONY += prepare-objtool
> > prepare-objtool: $(objtool_target)
> > -ifeq ($(SKIP_STACK_VALIDATION),1)
> > -ifdef CONFIG_UNWINDER_ORC
> > +ifneq ($(has_libelf),1)
> > + ifdef CONFIG_UNWINDER_ORC
> > @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
> > @false
> > -else
> > + else
> > + ifeq ($(SKIP_STACK_VALIDATION),1)
> > @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
>
>
> I think this would be more readable without the else branch:
>
> ifneq ($(has_libelf),1)
> ifdef <some objtool command config>
> <warn about unavailability>
Note: error not warn
> endif
> ifdef <another objtool command config>
> <warn ...>
> endif
> <...>
> endif
I think the next patch, which makes recordmcount a subcmd, makes it a
little clearer what the pattern is because it adds another ifdef block
in the way you suggest.
As for the else around the SKIP_STACK_VALIDATION check -- it is special
in a couple ways -- at least as best I can tell.
It's not a CONFIG_* -- it actually breaks the normal pattern with
CONFIG_* in that..
It's about a judgement call that it's OK to merely warn and skip the
stack validation rather than produce an error. The other, CONFIG_*
blocks produce errors.
These two reasons are why I think it makes sense to keep the logic
distinct with the "else".
Cheers,
-Matt Helsley
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types
2020-06-09 6:41 ` Kamalesh Babulal
@ 2020-06-09 18:12 ` Matt Helsley
2020-06-10 4:35 ` Kamalesh Babulal
0 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-09 18:12 UTC (permalink / raw)
To: Kamalesh Babulal
Cc: linux-kernel, Josh Poimboeuf, Peter Zijlstra, Steven Rostedt,
Sami Tolvanen, Julien Thierry
On Tue, Jun 09, 2020 at 12:11:55PM +0530, Kamalesh Babulal wrote:
> On 6/3/20 1:20 AM, Matt Helsley wrote:
> > Rather than building the exact ELF section data we need and
> > avoiding libelf's conversion step, use more GElf types
> > and then libelf's elfxx_xlatetof() functions to convert
> > the mcount locations (GElf_Addr) and associated relocations.
> >
> > This converts sift_rel_mcount() so that it doesn't use the
> > recordmcount wrapper. The next patch will move it out of the
> > wrapper.
> >
> > Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> > ---
> > tools/objtool/recordmcount.c | 44 +++----------
> > tools/objtool/recordmcount.h | 120 ++++++++++++++---------------------
> > 2 files changed, 59 insertions(+), 105 deletions(-)
> >
> > diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
> > index 06a8f8ddefa7..ef3c360a3db9 100644
> > --- a/tools/objtool/recordmcount.c
> > +++ b/tools/objtool/recordmcount.c
>
> [...]
>
> > -static uint_t *sift_rel_mcount(uint_t *mlocp,
> > - unsigned const offbase,
> > - Elf_Rel **const mrelpp,
> > +static void sift_rel_mcount(GElf_Addr **mlocpp,
> > + GElf_Sxword *r_offsetp,
> > + void **const mrelpp,
> > const struct section * const rels,
> > unsigned const recsym_index,
> > unsigned long const recval,
> > - unsigned const reltype)
> > + unsigned const reltype,
> > + bool is_rela)
> > {
> > - uint_t *const mloc0 = mlocp;
> > - Elf_Rel *mrelp = *mrelpp;
> > - unsigned int rel_entsize = rels->sh.sh_entsize;
> > - unsigned mcountsym = 0;
> > + GElf_Rel *mrelp = *mrelpp;
> > + GElf_Rela *mrelap = *mrelpp;
> > + unsigned int mcount_sym_info = 0;
> > struct reloc *reloc;
> >
> > list_for_each_entry(reloc, &rels->reloc_list, list) {
> > - if (!mcountsym)
> > - mcountsym = get_mcountsym(reloc);
> > -
> > - if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
> > - uint_t const addend =
> > - _w(reloc->offset - recval + mcount_adjust);
> > - mrelp->r_offset = _w(offbase
> > - + ((void *)mlocp - (void *)mloc0));
> > - Elf_r_info(mrelp, recsym_index, reltype);
> > - if (rel_entsize == sizeof(Elf_Rela)) {
> > - ((Elf_Rela *)mrelp)->r_addend = addend;
> > - *mlocp++ = 0;
> > - } else
> > - *mlocp++ = addend;
> > -
> > - mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
> > + unsigned long addend;
> > +
> > + if (!mcount_sym_info)
> > + mcount_sym_info = get_mcount_sym_info(reloc);
> > +
> > + if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc))
> > + continue;
>
> Hi Matt,
>
> I was trying out the patch series on ppc64le and found that __mcount_loc
> and .rela__mcount_loc section pairs do not get generated.
>
> # readelf -S fs/proc/cmdline.o|grep mcount
> #
>
> Debugged the cause to get_mcountsym()'s return type. It returns reloc
> type from GELF_R_INFO() and expects Elf64_Xword a.k.a unsigned long
> to be the return type but get_mcountsym() returns unsigned int on 64-bit.
>
> On power the _mcount is of relocation type R_PPC64_REL24 (info 0x170000000a),
> using unsigned int truncates the value to 0xa and fails the above check.
> Using below fix, that converts mcount_sym_info to use unsigned long, generates
> the __mcount_loc section pairs.
>
> --- a/tools/objtool/mcount.c
> +++ b/tools/objtool/mcount.c
> @@ -163,7 +163,7 @@ static int is_mcounted_section_name(char const *const txtname)
> strcmp(".cpuidle.text", txtname) == 0;
> }
>
> -static unsigned int get_mcount_sym_info(struct reloc *reloc)
> +static unsigned long get_mcount_sym_info(struct reloc *reloc)
> {
> struct symbol *sym = reloc->sym;
> char const *symname = sym->name;
> @@ -274,7 +274,7 @@ static int nop_mcount(struct section * const rels,
> {
> struct reloc *reloc;
> struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
> - unsigned int mcount_sym_info = 0;
> + unsigned long mcount_sym_info = 0;
> int once = 0;
>
> list_for_each_entry(reloc, &rels->reloc_list, list) {
> @@ -363,7 +363,7 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
> {
> GElf_Rel *mrelp = *mrelpp;
> GElf_Rela *mrelap = *mrelpp;
> - unsigned int mcount_sym_info = 0;
> + unsigned long mcount_sym_info = 0;
> struct reloc *reloc;
>
> list_for_each_entry(reloc, &rels->reloc_list, list) {
>
> # readelf -S fs/proc/cmdline.o|grep mcount
> [31] __mcount_loc PROGBITS 0000000000000000 00022f10
> [32] .rela__mcount_loc RELA 0000000000000000 00022f20
Fixed for next posting.
I've essentially added this as another patch before it moves into
recordmcount.c, gets renamed to get_mcount_sym_info(), etc. I did it
this way because it only becomes necessary to change the type before
moving the function (and eventually its callers) out of the wrapper.
I feel I should credit you as author or at least co-author of the added
patch since it's basically a "backported" version of the changes you
suggested. I reviewed the process in submitting-patches.rst and propose
the commit message:
objtool: mcount: Extend mcountsym size
Before we can move this function out of the wrapper and into
wordsize-independent code we need to explicitly size the
type returned from get_mcountsym() to preserve the symbol info.
Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Is that OK with you or do you have another preference?
>
>
> > +
> > + addend = reloc->offset - recval + mcount_adjust;
> > + if (is_rela) {
> > + mrelap->r_offset = *r_offsetp;
> > + mrelap->r_info = GELF_R_INFO(recsym_index, reltype);
> > + mrelap->r_addend = addend;
> > + mrelap++;
> > + **mlocpp = 0;
> > + } else {
> > + mrelp->r_offset = *r_offsetp;
> > + mrelp->r_info = GELF_R_INFO(recsym_index, reltype);
> > + mrelp++;
> > + **mlocpp = addend;
> > }
> > + (*mlocpp)++;
> > + r_offsetp += loc_size;
>
> the offsets generated for rela__mcount_loc section are incorrect:
>
> # readelf -rW fs/proc/meminfo.o
> [...]
> Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries:
> Offset Info Type Symbol's Value Symbol's Name + Addend
> 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c
> 00000a059c401f38 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64
> 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c
> 0000000000000000 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c
>
> changing the above line to *r_offsetp += loc_size and initializing
> r_offset=0 in do_mcount() generates the correct offset:
>
> # readelf -rW fs/proc/meminfo.o
> [...]
> Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries:
> Offset Info Type Symbol's Value Symbol's Name + Addend
> 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c
> 0000000000000008 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64
> 0000000000000010 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c
> 0000000000000018 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c
Fixed for next posting.
Thank you for testing these out and the fixes!
Cheers,
-Matt Helsley
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-09 9:00 ` Julien Thierry
@ 2020-06-09 18:39 ` Matt Helsley
2020-06-09 18:52 ` Steven Rostedt
2020-06-09 19:11 ` Julien Thierry
0 siblings, 2 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-09 18:39 UTC (permalink / raw)
To: Julien Thierry
Cc: linux-kernel, Josh Poimboeuf, Peter Zijlstra, Steven Rostedt,
Sami Tolvanen, Kamalesh Babulal
On Tue, Jun 09, 2020 at 10:00:59AM +0100, Julien Thierry wrote:
> Hi Matt,
>
> On 6/2/20 8:49 PM, Matt Helsley wrote:
> > Rather than a standalone executable merge recordmcount as a sub command
> > of objtool. This is a small step towards cleaning up recordmcount and
> > eventually sharing ELF code with objtool.
> >
> > For the initial step all that's required is a bit of Makefile changes
> > and invoking the former main() function from recordmcount.c because the
> > subcommand code uses similar function arguments as main when dispatching.
> >
> > objtool ignores some object files that tracing does not, specifically
> > those with OBJECT_FILES_NON_STANDARD Makefile variables. For this reason
> > we keep the recordmcount_dep separate from the objtool_dep. When using
> > objtool mcount we can also, like the other objtool invocations, just
> > depend on the binary rather than the source the binary is built from.
> >
> > Subsequent patches will gradually convert recordmcount to use
> > more and more of libelf/objtool's ELF accessor code. This will both
> > clean up recordmcount to be more easily readable and remove
> > recordmcount's crude accessor wrapping code.
> >
> > Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> > ---
...
> > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> > index 743647005f64..ae74647b06fa 100644
> > --- a/kernel/trace/Kconfig
> > +++ b/kernel/trace/Kconfig
> > @@ -59,7 +59,7 @@ config HAVE_NOP_MCOUNT
> > config HAVE_C_RECORDMCOUNT
> > bool
> > help
> > - C version of recordmcount available?
> > + C version of objtool mcount available?
>
> The "C version" doesn't make much sense here. "Objtool mcount available?" or
> "mcount subcommand of objtool available?" perhaps?
Agreed, "C version" is nonsense at this point.
Looking at the other HAVE_* help messages in that Kconfig suggests:
Arch supports objtool mcount subcommand
So I've changed it to that.
> > diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
> > index 285474a77fe9..ffef73f7f47e 100644
> > --- a/tools/objtool/Makefile
> > +++ b/tools/objtool/Makefile
> > @@ -31,12 +31,6 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
> > LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
> > LIBELF_LIBS := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
> > -RECORDMCOUNT := $(OUTPUT)recordmcount
> > -RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
> > -ifeq ($(BUILD_C_RECORDMCOUNT),y)
> > -all: $(RECORDMCOUNT)
> > -endif
> > -
> > all: $(OBJTOOL)
> > INCLUDES := -I$(srctree)/tools/include \
> > @@ -55,13 +49,47 @@ AWK = awk
> > SUBCMD_CHECK := n
> > SUBCMD_ORC := n
> > +SUBCMD_MCOUNT := n
> > ifeq ($(SRCARCH),x86)
> > SUBCMD_CHECK := y
> > SUBCMD_ORC := y
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),arm)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),arm64)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),ia64)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),mips)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),powerpc)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),s390)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),sh)
> > + SUBCMD_MCOUNT := y
> > +endif
> > +
> > +ifeq ($(SRCARCH),sparc)
> > + SUBCMD_MCOUNT := y
>
> Is there some arch for which MCOUNT is not supported? If not you could just
> have MCOUNT default to 'y' and avoid adding all those tests (or maybe reduce
> the numbers and set to 'n' only for arches not supporting it).
Yes, there are some which it does not support. For those architectures
we keep recordmcount.pl around.
It occured to me that with your suggestion to use more CONFIG_ variables
we could eliminate this pattern and replace it with these pseudo-patches:
+++ b/kernel/trace/Kconfig
+config OBJTOOL_SUBCMD_MCOUNT
+ bool
+ depends on HAVE_C_RECORDMCOUNT
+ select OBJTOOL_SUBCMDS
+ help
+ Record mcount call locations using objtool
and then change the Makefiles to use the CONFIG_ variables
rather than have one ifeq block per arch:
+++ b/tools/objtool/Makefile
+SUBCMD_MCOUNT := $(CONFIG_OBJTOOL_SUBCMD_MCOUNT)
Does this seem like a good use of CONFIG_ variables or is it going too
far?
I haven't changed to this pattern just yet -- I'm hoping you and Josh
or Peter might weigh in with your preferences.
>
> > endif
> > -export SUBCMD_CHECK SUBCMD_ORC
> > +export SUBCMD_CHECK SUBCMD_ORC SUBCMD_MCOUNT
...
> > diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
> > index 85c979caa367..9c7331592fa7 100644
> > --- a/tools/objtool/builtin.h
> > +++ b/tools/objtool/builtin.h
> > @@ -12,5 +12,7 @@ extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
> > extern int cmd_check(int argc, const char **argv);
> > extern int cmd_orc(int argc, const char **argv);
> > +extern bool is_cmd_mcount_available(void);
>
> This appears to be unused.
Indeed, removed.
Thanks!
Cheers,
-Matt Helsley
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-09 18:39 ` Matt Helsley
@ 2020-06-09 18:52 ` Steven Rostedt
2020-06-09 18:56 ` Matt Helsley
2020-06-09 19:11 ` Julien Thierry
1 sibling, 1 reply; 49+ messages in thread
From: Steven Rostedt @ 2020-06-09 18:52 UTC (permalink / raw)
To: Matt Helsley
Cc: Julien Thierry, linux-kernel, Josh Poimboeuf, Peter Zijlstra,
Sami Tolvanen, Kamalesh Babulal
On Tue, 9 Jun 2020 11:39:51 -0700
Matt Helsley <mhelsley@vmware.com> wrote:
> > > +ifeq ($(SRCARCH),sparc)
> > > + SUBCMD_MCOUNT := y
> >
> > Is there some arch for which MCOUNT is not supported? If not you could just
> > have MCOUNT default to 'y' and avoid adding all those tests (or maybe reduce
> > the numbers and set to 'n' only for arches not supporting it).
>
> Yes, there are some which it does not support. For those architectures
> we keep recordmcount.pl around.
>
> It occured to me that with your suggestion to use more CONFIG_ variables
> we could eliminate this pattern and replace it with these pseudo-patches:
>
> +++ b/kernel/trace/Kconfig
>
> +config OBJTOOL_SUBCMD_MCOUNT
> + bool
> + depends on HAVE_C_RECORDMCOUNT
> + select OBJTOOL_SUBCMDS
> + help
> + Record mcount call locations using objtool
>
> and then change the Makefiles to use the CONFIG_ variables
> rather than have one ifeq block per arch:
>
> +++ b/tools/objtool/Makefile
>
> +SUBCMD_MCOUNT := $(CONFIG_OBJTOOL_SUBCMD_MCOUNT)
If you can make this work, this is definitely the way to go.
-- Steve
>
> Does this seem like a good use of CONFIG_ variables or is it going too
> far?
>
> I haven't changed to this pattern just yet -- I'm hoping you and Josh
> or Peter might weigh in with your preferences.
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-09 18:52 ` Steven Rostedt
@ 2020-06-09 18:56 ` Matt Helsley
0 siblings, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-09 18:56 UTC (permalink / raw)
To: Steven Rostedt
Cc: Julien Thierry, linux-kernel, Josh Poimboeuf, Peter Zijlstra,
Sami Tolvanen, Kamalesh Babulal
On Tue, Jun 09, 2020 at 02:52:07PM -0400, Steven Rostedt wrote:
> On Tue, 9 Jun 2020 11:39:51 -0700
> Matt Helsley <mhelsley@vmware.com> wrote:
>
> > > > +ifeq ($(SRCARCH),sparc)
> > > > + SUBCMD_MCOUNT := y
> > >
> > > Is there some arch for which MCOUNT is not supported? If not you could just
> > > have MCOUNT default to 'y' and avoid adding all those tests (or maybe reduce
> > > the numbers and set to 'n' only for arches not supporting it).
> >
> > Yes, there are some which it does not support. For those architectures
> > we keep recordmcount.pl around.
> >
> > It occured to me that with your suggestion to use more CONFIG_ variables
> > we could eliminate this pattern and replace it with these pseudo-patches:
> >
> > +++ b/kernel/trace/Kconfig
> >
> > +config OBJTOOL_SUBCMD_MCOUNT
> > + bool
> > + depends on HAVE_C_RECORDMCOUNT
> > + select OBJTOOL_SUBCMDS
> > + help
> > + Record mcount call locations using objtool
> >
> > and then change the Makefiles to use the CONFIG_ variables
> > rather than have one ifeq block per arch:
> >
> > +++ b/tools/objtool/Makefile
> >
> > +SUBCMD_MCOUNT := $(CONFIG_OBJTOOL_SUBCMD_MCOUNT)
>
> If you can make this work, this is definitely the way to go.
I think I can so I'll give it a go!
Cheers,
-Matt Helsley
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd
2020-06-09 18:39 ` Matt Helsley
2020-06-09 18:52 ` Steven Rostedt
@ 2020-06-09 19:11 ` Julien Thierry
1 sibling, 0 replies; 49+ messages in thread
From: Julien Thierry @ 2020-06-09 19:11 UTC (permalink / raw)
To: Matt Helsley, linux-kernel, Josh Poimboeuf, Peter Zijlstra,
Steven Rostedt, Sami Tolvanen, Kamalesh Babulal
On 6/9/20 7:39 PM, Matt Helsley wrote:
> On Tue, Jun 09, 2020 at 10:00:59AM +0100, Julien Thierry wrote:
>> Hi Matt,
>>
>> On 6/2/20 8:49 PM, Matt Helsley wrote:
>>> Rather than a standalone executable merge recordmcount as a sub command
>>> of objtool. This is a small step towards cleaning up recordmcount and
>>> eventually sharing ELF code with objtool.
>>>
>>> For the initial step all that's required is a bit of Makefile changes
>>> and invoking the former main() function from recordmcount.c because the
>>> subcommand code uses similar function arguments as main when dispatching.
>>>
>>> objtool ignores some object files that tracing does not, specifically
>>> those with OBJECT_FILES_NON_STANDARD Makefile variables. For this reason
>>> we keep the recordmcount_dep separate from the objtool_dep. When using
>>> objtool mcount we can also, like the other objtool invocations, just
>>> depend on the binary rather than the source the binary is built from.
>>>
>>> Subsequent patches will gradually convert recordmcount to use
>>> more and more of libelf/objtool's ELF accessor code. This will both
>>> clean up recordmcount to be more easily readable and remove
>>> recordmcount's crude accessor wrapping code.
>>>
>>> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
>>> ---
> ...
>>> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
>>> index 743647005f64..ae74647b06fa 100644
>>> --- a/kernel/trace/Kconfig
>>> +++ b/kernel/trace/Kconfig
>>> @@ -59,7 +59,7 @@ config HAVE_NOP_MCOUNT
>>> config HAVE_C_RECORDMCOUNT
>>> bool
>>> help
>>> - C version of recordmcount available?
>>> + C version of objtool mcount available?
>>
>> The "C version" doesn't make much sense here. "Objtool mcount available?" or
>> "mcount subcommand of objtool available?" perhaps?
>
> Agreed, "C version" is nonsense at this point.
>
> Looking at the other HAVE_* help messages in that Kconfig suggests:
>
> Arch supports objtool mcount subcommand
>
> So I've changed it to that.
>
Yes, that seems good.
>>> diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
>>> index 285474a77fe9..ffef73f7f47e 100644
>>> --- a/tools/objtool/Makefile
>>> +++ b/tools/objtool/Makefile
>>> @@ -31,12 +31,6 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
>>> LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
>>> LIBELF_LIBS := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
>>> -RECORDMCOUNT := $(OUTPUT)recordmcount
>>> -RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
>>> -ifeq ($(BUILD_C_RECORDMCOUNT),y)
>>> -all: $(RECORDMCOUNT)
>>> -endif
>>> -
>>> all: $(OBJTOOL)
>>> INCLUDES := -I$(srctree)/tools/include \
>>> @@ -55,13 +49,47 @@ AWK = awk
>>> SUBCMD_CHECK := n
>>> SUBCMD_ORC := n
>>> +SUBCMD_MCOUNT := n
>>> ifeq ($(SRCARCH),x86)
>>> SUBCMD_CHECK := y
>>> SUBCMD_ORC := y
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),arm)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),arm64)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),ia64)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),mips)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),powerpc)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),s390)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),sh)
>>> + SUBCMD_MCOUNT := y
>>> +endif
>>> +
>>> +ifeq ($(SRCARCH),sparc)
>>> + SUBCMD_MCOUNT := y
>>
>> Is there some arch for which MCOUNT is not supported? If not you could just
>> have MCOUNT default to 'y' and avoid adding all those tests (or maybe reduce
>> the numbers and set to 'n' only for arches not supporting it).
>
> Yes, there are some which it does not support. For those architectures
> we keep recordmcount.pl around.
>
> It occured to me that with your suggestion to use more CONFIG_ variables
> we could eliminate this pattern and replace it with these pseudo-patches:
>
> +++ b/kernel/trace/Kconfig
>
> +config OBJTOOL_SUBCMD_MCOUNT
> + bool
> + depends on HAVE_C_RECORDMCOUNT
> + select OBJTOOL_SUBCMDS
> + help
> + Record mcount call locations using objtool
>
> and then change the Makefiles to use the CONFIG_ variables
> rather than have one ifeq block per arch:
>
> +++ b/tools/objtool/Makefile
>
> +SUBCMD_MCOUNT := $(CONFIG_OBJTOOL_SUBCMD_MCOUNT)
>
> Does this seem like a good use of CONFIG_ variables or is it going too
> far?
>
Definitely seems like a good idea to me! Will be a nice improvement.
Cheers,
--
Julien Thierry
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount
2020-06-09 15:42 ` Matt Helsley
@ 2020-06-09 19:31 ` Julien Thierry
0 siblings, 0 replies; 49+ messages in thread
From: Julien Thierry @ 2020-06-09 19:31 UTC (permalink / raw)
To: Matt Helsley, linux-kernel, Josh Poimboeuf, Peter Zijlstra,
Steven Rostedt, Sami Tolvanen, Kamalesh Babulal
On 6/9/20 4:42 PM, Matt Helsley wrote:
> On Tue, Jun 09, 2020 at 09:54:33AM +0100, Julien Thierry wrote:
>> Hi Matt,
>>
>> On 6/2/20 8:49 PM, Matt Helsley wrote:
>>> Move recordmcount into the objtool directory. We keep this step separate
>>> so changes which turn recordmcount into a subcommand of objtool don't
>>> get obscured.
>>>
>>> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
>
> <snip>
>
>>> diff --git a/Makefile b/Makefile
>>> index 04f5662ae61a..d353a0a65a71 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -844,6 +844,7 @@ ifdef CONFIG_DYNAMIC_FTRACE
>>> ifdef CONFIG_HAVE_C_RECORDMCOUNT
>>> BUILD_C_RECORDMCOUNT := y
>>> export BUILD_C_RECORDMCOUNT
>>> + objtool_target := tools/objtool FORCE
>>> endif
>>> endif
>>> endif
>>> @@ -1023,10 +1024,10 @@ endif
>>> export mod_sign_cmd
>>> HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
>>> +has_libelf := $(call try-run,\
>>> + echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
>>
>> Maybe there could be some build dependency, e.g. CONFIG_OBJTOOL_SUBCMDS that
>> sets the "objtool_target" and "has_libelf" when selected.
>>
>> Then the CONFIG_UNWINDER_ORC, RECORD_MCOUNT and STACK_VALIDATION would just
>> had to select that config option.
>
> That might save a good amount of control flow in the Makefiles.
>
> We could take it one step further and have specific CONFIG_OBJTOOL_<subcmd>
> which might help us remove the per-architecture control-flow in
> the multi-arch subcmd support found in tools/objtool/Makefile.
> > What do folks think of that -- too far?
>
I wasn't completely sure I understood before I saw your reply on the
next patch. I don't think it's too far, it's cleaner! The current way
was good enough to deal with only two x86 specific objtool subcommands.
Since you're adding another one and it is likely that more will be added
in the future, I think it's worth having something a bit more structured
:) .
>>
>>> ifdef CONFIG_STACK_VALIDATION
>>> - has_libelf := $(call try-run,\
>>> - echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
>>> ifeq ($(has_libelf),1)
>>> objtool_target := tools/objtool FORCE
>>> else
>>> @@ -1163,13 +1164,15 @@ uapi-asm-generic:
>>> PHONY += prepare-objtool
>>> prepare-objtool: $(objtool_target)
>>> -ifeq ($(SKIP_STACK_VALIDATION),1)
>>> -ifdef CONFIG_UNWINDER_ORC
>>> +ifneq ($(has_libelf),1)
>>> + ifdef CONFIG_UNWINDER_ORC
>>> @echo "error: Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
>>> @false
>>> -else
>>> + else
>>> + ifeq ($(SKIP_STACK_VALIDATION),1)
>>> @echo "warning: Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
>>
>>
>> I think this would be more readable without the else branch:
>>
>> ifneq ($(has_libelf),1)
>> ifdef <some objtool command config>
>> <warn about unavailability>
>
> Note: error not warn
>
Good point. But since those are errors, you don't need the "else" :)
>> endif
>> ifdef <another objtool command config>
>> <warn ...>
>> endif
>> <...>
>> endif
>
> I think the next patch, which makes recordmcount a subcmd, makes it a
> little clearer what the pattern is because it adds another ifdef block
> in the way you suggest.
>
> As for the else around the SKIP_STACK_VALIDATION check -- it is special
> in a couple ways -- at least as best I can tell.
>
> It's not a CONFIG_* -- it actually breaks the normal pattern with
> CONFIG_* in that..
>
Yes but $(SKIP_STACK_VALIDATION) == 1 is actually just
CONFIG_STACK_VALIDATION && ($(has_libelf) != 1). And since you are
already in the ifneq ($(has_libelf),1) branch, checking
$(SKIP_STACK_VALIDATION) == 1 is the same as CONFIG_STACK_VALIDATION
being defined.
> It's about a judgement call that it's OK to merely warn and skip the
> stack validation rather than produce an error. The other, CONFIG_*
> blocks produce errors.
>
To me this is minor, we could also imagine another command CONFIG_
performing another action than warning or error when libelf is not
available.
Anyway, this was just a suggestion, I don't want to insist to much on this.
Cheers,
--
Julien Thierry
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types
2020-06-09 18:12 ` Matt Helsley
@ 2020-06-10 4:35 ` Kamalesh Babulal
0 siblings, 0 replies; 49+ messages in thread
From: Kamalesh Babulal @ 2020-06-10 4:35 UTC (permalink / raw)
To: Matt Helsley, linux-kernel, Josh Poimboeuf, Peter Zijlstra,
Steven Rostedt, Sami Tolvanen, Julien Thierry
On 6/9/20 11:42 PM, Matt Helsley wrote:
[...]
>> Hi Matt,
>>
>> I was trying out the patch series on ppc64le and found that __mcount_loc
>> and .rela__mcount_loc section pairs do not get generated.
>>
>> # readelf -S fs/proc/cmdline.o|grep mcount
>> #
>>
>> Debugged the cause to get_mcountsym()'s return type. It returns reloc
>> type from GELF_R_INFO() and expects Elf64_Xword a.k.a unsigned long
>> to be the return type but get_mcountsym() returns unsigned int on 64-bit.
>>
>> On power the _mcount is of relocation type R_PPC64_REL24 (info 0x170000000a),
>> using unsigned int truncates the value to 0xa and fails the above check.
>> Using below fix, that converts mcount_sym_info to use unsigned long, generates
>> the __mcount_loc section pairs.
>>
>> --- a/tools/objtool/mcount.c
>> +++ b/tools/objtool/mcount.c
>> @@ -163,7 +163,7 @@ static int is_mcounted_section_name(char const *const txtname)
>> strcmp(".cpuidle.text", txtname) == 0;
>> }
>>
>> -static unsigned int get_mcount_sym_info(struct reloc *reloc)
>> +static unsigned long get_mcount_sym_info(struct reloc *reloc)
>> {
>> struct symbol *sym = reloc->sym;
>> char const *symname = sym->name;
>> @@ -274,7 +274,7 @@ static int nop_mcount(struct section * const rels,
>> {
>> struct reloc *reloc;
>> struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
>> - unsigned int mcount_sym_info = 0;
>> + unsigned long mcount_sym_info = 0;
>> int once = 0;
>>
>> list_for_each_entry(reloc, &rels->reloc_list, list) {
>> @@ -363,7 +363,7 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
>> {
>> GElf_Rel *mrelp = *mrelpp;
>> GElf_Rela *mrelap = *mrelpp;
>> - unsigned int mcount_sym_info = 0;
>> + unsigned long mcount_sym_info = 0;
>> struct reloc *reloc;
>>
>> list_for_each_entry(reloc, &rels->reloc_list, list) {
>>
>> # readelf -S fs/proc/cmdline.o|grep mcount
>> [31] __mcount_loc PROGBITS 0000000000000000 00022f10
>> [32] .rela__mcount_loc RELA 0000000000000000 00022f20
>
> Fixed for next posting.
>
> I've essentially added this as another patch before it moves into
> recordmcount.c, gets renamed to get_mcount_sym_info(), etc. I did it
> this way because it only becomes necessary to change the type before
> moving the function (and eventually its callers) out of the wrapper.
>
> I feel I should credit you as author or at least co-author of the added
> patch since it's basically a "backported" version of the changes you
> suggested. I reviewed the process in submitting-patches.rst and propose
> the commit message:
>
> objtool: mcount: Extend mcountsym size
>
> Before we can move this function out of the wrapper and into
> wordsize-independent code we need to explicitly size the
> type returned from get_mcountsym() to preserve the symbol info.
>
> Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
>
> Is that OK with you or do you have another preference?
Thanks, it works for me.
--
Kamalesh
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-02 19:50 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
@ 2020-06-12 13:26 ` Peter Zijlstra
2020-06-12 16:05 ` Peter Zijlstra
2020-06-13 19:49 ` Matt Helsley
0 siblings, 2 replies; 49+ messages in thread
From: Peter Zijlstra @ 2020-06-12 13:26 UTC (permalink / raw)
To: Matt Helsley
Cc: linux-kernel, Josh Poimboeuf, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal
On Tue, Jun 02, 2020 at 12:50:11PM -0700, Matt Helsley wrote:
> +static int nop_mcount(struct section * const rels,
> + const char *const txtname)
> +{
> + struct reloc *reloc;
> + struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
> + unsigned mcountsym = 0;
> + int once = 0;
> +
> + list_for_each_entry(reloc, &rels->reloc_list, list) {
> + int ret = -1;
> +
> + if (!mcountsym)
> + mcountsym = get_mcountsym(reloc);
> +
> + if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
This makes no sense to me; why not have mcountsym be a 'struct symbol
*' and have get_mcountsym() return one of those.
if (reloc->sym == mcountsym && ... )
is much nicer, no?
> + if (make_nop) {
> + ret = make_nop(txts, reloc->offset);
> + if (ret < 0)
> + return -1;
> + }
> + if (warn_on_notrace_sect && !once) {
> + printf("Section %s has mcount callers being ignored\n",
> + txtname);
> + once = 1;
> + /* just warn? */
> + if (!make_nop)
> + return 0;
> + }
> + }
> +
> + /*
> + * If we successfully removed the mcount, mark the relocation
> + * as a nop (don't do anything with it).
> + */
> + if (!ret) {
> + reloc->type = rel_type_nop;
> + rels->changed = true;
I have an elf_write_rela(), I'll make sure to Cc you.
> + }
> + }
> + return 0;
> +}
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-12 13:26 ` Peter Zijlstra
@ 2020-06-12 16:05 ` Peter Zijlstra
2020-06-17 17:36 ` Matt Helsley
2020-06-13 19:49 ` Matt Helsley
1 sibling, 1 reply; 49+ messages in thread
From: Peter Zijlstra @ 2020-06-12 16:05 UTC (permalink / raw)
To: Matt Helsley
Cc: linux-kernel, Josh Poimboeuf, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal
On Fri, Jun 12, 2020 at 03:26:57PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 02, 2020 at 12:50:11PM -0700, Matt Helsley wrote:
> > +static int nop_mcount(struct section * const rels,
> > + const char *const txtname)
> > +{
> > + struct reloc *reloc;
> > + struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
> > + unsigned mcountsym = 0;
> > + int once = 0;
> > +
> > + list_for_each_entry(reloc, &rels->reloc_list, list) {
> > + int ret = -1;
> > +
> > + if (!mcountsym)
> > + mcountsym = get_mcountsym(reloc);
> > +
> > + if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
>
> This makes no sense to me; why not have mcountsym be a 'struct symbol
> *' and have get_mcountsym() return one of those.
>
> if (reloc->sym == mcountsym && ... )
>
> is much nicer, no?
On top of that, I suppose we can do something like the below.
Then you can simply write:
if (reloc->sym->class == SYM_MCOUNT && ..)
---
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 45452facff3b..94e4b8fcf9c1 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
# Any varying coverage in these files is non-deterministic
# and is generally not a function of system call inputs.
-KCOV_INSTRUMENT := n
+# KCOV_INSTRUMENT := n
obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 432417a83902..133c0c285be6 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -341,6 +341,24 @@ static int read_sections(struct elf *elf)
return 0;
}
+static bool is_mcount_symbol(const char *name)
+{
+ if (name[0] == '.')
+ name++;
+
+ if (name[0] == '_')
+ name++;
+
+ return !strcmp(name, "mcount", 6) ||
+ !strcmp(name, "_fentry__") ||
+ !strcmp(name, "_gnu_mcount_nc");
+}
+
+static bool is_kcov_symbol(const char *name)
+{
+ return !strncmp(name, "__sanitizer_cov_", 16);
+}
+
static int read_symbols(struct elf *elf)
{
struct section *symtab, *symtab_shndx, *sec;
@@ -410,6 +428,12 @@ static int read_symbols(struct elf *elf)
} else
sym->sec = find_section_by_index(elf, 0);
+
+ if (is_mcount_symbol(sym->name))
+ sym->class = SYM_MCOUNT;
+ else if (is_kcov_symbol(sym->name))
+ sym->class = SYM_KCOV;
+
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 78a2db23b8b6..3c1cccb7b5ff 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -42,6 +42,12 @@ struct section {
bool changed, text, rodata, noinstr;
};
+enum symbol_class {
+ SYM_REGULAR = 0,
+ SYM_MCOUNT,
+ SYM_KCOV,
+};
+
struct symbol {
struct list_head list;
struct rb_node node;
@@ -55,6 +61,7 @@ struct symbol {
unsigned long offset;
unsigned int len;
struct symbol *pfunc, *cfunc, *alias;
+ enum symbol_class class;
bool uaccess_safe;
};
^ permalink raw reply related [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-12 13:26 ` Peter Zijlstra
2020-06-12 16:05 ` Peter Zijlstra
@ 2020-06-13 19:49 ` Matt Helsley
1 sibling, 0 replies; 49+ messages in thread
From: Matt Helsley @ 2020-06-13 19:49 UTC (permalink / raw)
To: Peter Zijlstra
Cc: linux-kernel, Josh Poimboeuf, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal
On Fri, Jun 12, 2020 at 03:26:56PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 02, 2020 at 12:50:11PM -0700, Matt Helsley wrote:
> > +static int nop_mcount(struct section * const rels,
> > + const char *const txtname)
> > +{
> > + struct reloc *reloc;
> > + struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
> > + unsigned mcountsym = 0;
> > + int once = 0;
> > +
> > + list_for_each_entry(reloc, &rels->reloc_list, list) {
> > + int ret = -1;
> > +
> > + if (!mcountsym)
> > + mcountsym = get_mcountsym(reloc);
> > +
> > + if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
>
> This makes no sense to me; why not have mcountsym be a 'struct symbol
> *' and have get_mcountsym() return one of those.
>
> if (reloc->sym == mcountsym && ... )
>
> is much nicer, no?
Indeed! I'll change it from returning an unsigned long to struct symbol * before I
move it out of the wrapper code.
>
> > + if (make_nop) {
> > + ret = make_nop(txts, reloc->offset);
> > + if (ret < 0)
> > + return -1;
> > + }
> > + if (warn_on_notrace_sect && !once) {
> > + printf("Section %s has mcount callers being ignored\n",
> > + txtname);
> > + once = 1;
> > + /* just warn? */
> > + if (!make_nop)
> > + return 0;
> > + }
> > + }
> > +
> > + /*
> > + * If we successfully removed the mcount, mark the relocation
> > + * as a nop (don't do anything with it).
> > + */
> > + if (!ret) {
> > + reloc->type = rel_type_nop;
> > + rels->changed = true;
>
> I have an elf_write_rela(), I'll make sure to Cc you.
Thanks! I might also make use of your patch to rewrite instructions. We
need a way to turn certain prologue instructions into nops. Would it be
more widely useful to move that functionality out of mcount and into
the objtool ELF/per-arch code or do you think it's better inside the
mcount subcommand code?
Cheers,
-Matt
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-12 16:05 ` Peter Zijlstra
@ 2020-06-17 17:36 ` Matt Helsley
2020-06-17 18:30 ` Peter Zijlstra
0 siblings, 1 reply; 49+ messages in thread
From: Matt Helsley @ 2020-06-17 17:36 UTC (permalink / raw)
To: Peter Zijlstra
Cc: linux-kernel, Josh Poimboeuf, Steven Rostedt, Sami Tolvanen,
Julien Thierry, Kamalesh Babulal
On Fri, Jun 12, 2020 at 06:05:34PM +0200, Peter Zijlstra wrote:
> On Fri, Jun 12, 2020 at 03:26:57PM +0200, Peter Zijlstra wrote:
> > On Tue, Jun 02, 2020 at 12:50:11PM -0700, Matt Helsley wrote:
> > > +static int nop_mcount(struct section * const rels,
> > > + const char *const txtname)
> > > +{
> > > + struct reloc *reloc;
> > > + struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
> > > + unsigned mcountsym = 0;
> > > + int once = 0;
> > > +
> > > + list_for_each_entry(reloc, &rels->reloc_list, list) {
> > > + int ret = -1;
> > > +
> > > + if (!mcountsym)
> > > + mcountsym = get_mcountsym(reloc);
> > > +
> > > + if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
> >
> > This makes no sense to me; why not have mcountsym be a 'struct symbol
> > *' and have get_mcountsym() return one of those.
> >
> > if (reloc->sym == mcountsym && ... )
> >
> > is much nicer, no?
(this is already incorporated in my unposted revisions but...)
>
> On top of that, I suppose we can do something like the below.
>
> Then you can simply write:
>
> if (reloc->sym->class == SYM_MCOUNT && ..)
This looks like a good way to move towards a "single pass" through the ELF data
for mcount.
What order do you want to see this patch go in? Before this series (i.e. perhaps
just a kcov SYM_ class to start)? Early or late in this series? After?
Right now I'm thinking of putting this on the end of my series because
I'm focusing on converting recordmcount in the series and this isn't
strictly necessary but is definitely nicer.
>
> ---
>
> diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
> index 45452facff3b..94e4b8fcf9c1 100644
> --- a/kernel/locking/Makefile
> +++ b/kernel/locking/Makefile
> @@ -1,7 +1,7 @@
> # SPDX-License-Identifier: GPL-2.0
> # Any varying coverage in these files is non-deterministic
> # and is generally not a function of system call inputs.
> -KCOV_INSTRUMENT := n
> +# KCOV_INSTRUMENT := n
>
> obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
>
> diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
> index 432417a83902..133c0c285be6 100644
> --- a/tools/objtool/elf.c
> +++ b/tools/objtool/elf.c
> @@ -341,6 +341,24 @@ static int read_sections(struct elf *elf)
> return 0;
> }
>
> +static bool is_mcount_symbol(const char *name)
> +{
> + if (name[0] == '.')
> + name++;
> +
> + if (name[0] == '_')
> + name++;
> +
> + return !strcmp(name, "mcount", 6) ||
Looks like you intended this to be a strncmp() but I don't see a reason to
use strncmp(). Am I missing something?
> + !strcmp(name, "_fentry__") ||
> + !strcmp(name, "_gnu_mcount_nc");
> +}
This mashes all of the arch-specific mcount name checks together. I
don't see a problem with that because I doubt there will be a collision
with other functions. Just to be careful I looked through the Clang and
GCC sources, though I only dug through the history of Clang's output --
GCC's history with respect to mcount symbol names across architectures is
much harder to trace so I only looked at the current sources.
<snip> (the rest looks good)
Cheers,
-Matt Helsley
^ permalink raw reply [flat|nested] 49+ messages in thread
* Re: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
2020-06-17 17:36 ` Matt Helsley
@ 2020-06-17 18:30 ` Peter Zijlstra
0 siblings, 0 replies; 49+ messages in thread
From: Peter Zijlstra @ 2020-06-17 18:30 UTC (permalink / raw)
To: Matt Helsley, linux-kernel, Josh Poimboeuf, Steven Rostedt,
Sami Tolvanen, Julien Thierry, Kamalesh Babulal
On Wed, Jun 17, 2020 at 10:36:20AM -0700, Matt Helsley wrote:
> On Fri, Jun 12, 2020 at 06:05:34PM +0200, Peter Zijlstra wrote:
> > On top of that, I suppose we can do something like the below.
> >
> > Then you can simply write:
> >
> > if (reloc->sym->class == SYM_MCOUNT && ..)
>
> This looks like a good way to move towards a "single pass" through the ELF data
> for mcount.
>
> What order do you want to see this patch go in? Before this series (i.e. perhaps
> just a kcov SYM_ class to start)? Early or late in this series? After?
>
> Right now I'm thinking of putting this on the end of my series because
> I'm focusing on converting recordmcount in the series and this isn't
> strictly necessary but is definitely nicer.
No particular thoughts about where, so at the end would be fine.
> > ---
> >
> > diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
> > index 45452facff3b..94e4b8fcf9c1 100644
> > --- a/kernel/locking/Makefile
> > +++ b/kernel/locking/Makefile
> > @@ -1,7 +1,7 @@
> > # SPDX-License-Identifier: GPL-2.0
> > # Any varying coverage in these files is non-deterministic
> > # and is generally not a function of system call inputs.
> > -KCOV_INSTRUMENT := n
> > +# KCOV_INSTRUMENT := n
> >
> > obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
> >
> > diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
> > index 432417a83902..133c0c285be6 100644
> > --- a/tools/objtool/elf.c
> > +++ b/tools/objtool/elf.c
> > @@ -341,6 +341,24 @@ static int read_sections(struct elf *elf)
> > return 0;
> > }
> >
> > +static bool is_mcount_symbol(const char *name)
> > +{
> > + if (name[0] == '.')
> > + name++;
> > +
> > + if (name[0] == '_')
> > + name++;
> > +
> > + return !strcmp(name, "mcount", 6) ||
>
> Looks like you intended this to be a strncmp() but I don't see a reason to
> use strncmp(). Am I missing something?
typing hard :-)
> > + !strcmp(name, "_fentry__") ||
> > + !strcmp(name, "_gnu_mcount_nc");
> > +}
>
> This mashes all of the arch-specific mcount name checks together. I
> don't see a problem with that because I doubt there will be a collision
> with other functions.
This, I assumed it would just work.
> Just to be careful I looked through the Clang and
> GCC sources, though I only dug through the history of Clang's output --
> GCC's history with respect to mcount symbol names across architectures is
> much harder to trace so I only looked at the current sources.
Fair enough; thanks for the due-dilligence.
^ permalink raw reply [flat|nested] 49+ messages in thread
end of thread, other threads:[~2020-06-17 18:30 UTC | newest]
Thread overview: 49+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
2020-06-09 8:54 ` Julien Thierry
2020-06-09 15:42 ` Matt Helsley
2020-06-09 19:31 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
2020-06-09 9:00 ` Julien Thierry
2020-06-09 18:39 ` Matt Helsley
2020-06-09 18:52 ` Steven Rostedt
2020-06-09 18:56 ` Matt Helsley
2020-06-09 19:11 ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
2020-06-12 13:26 ` Peter Zijlstra
2020-06-12 16:05 ` Peter Zijlstra
2020-06-17 17:36 ` Matt Helsley
2020-06-17 18:30 ` Peter Zijlstra
2020-06-13 19:49 ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
2020-06-09 6:41 ` Kamalesh Babulal
2020-06-09 18:12 ` Matt Helsley
2020-06-10 4:35 ` Kamalesh Babulal
2020-06-02 19:50 ` [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 32/32] objtool: mcount: Rename Matt Helsley
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