From: Sami Tolvanen <samitolvanen@google.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Will Deacon <will@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com,
kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org,
Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v7 03/17] kbuild: lto: fix module versioning
Date: Wed, 18 Nov 2020 14:07:17 -0800 [thread overview]
Message-ID: <20201118220731.925424-4-samitolvanen@google.com> (raw)
In-Reply-To: <20201118220731.925424-1-samitolvanen@google.com>
With CONFIG_MODVERSIONS, version information is linked into each
compilation unit that exports symbols. With LTO, we cannot use this
method as all C code is compiled into LLVM bitcode instead. This
change collects symbol versions into .symversions files and merges
them in link-vmlinux.sh where they are all linked into vmlinux.o at
the same time.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
.gitignore | 1 +
Makefile | 3 ++-
arch/Kconfig | 1 -
scripts/Makefile.build | 33 +++++++++++++++++++++++++++++++--
scripts/Makefile.modpost | 6 +++++-
scripts/link-vmlinux.sh | 23 ++++++++++++++++++++++-
6 files changed, 61 insertions(+), 6 deletions(-)
diff --git a/.gitignore b/.gitignore
index d01cda8e1177..44e34991875e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,6 +41,7 @@
*.so.dbg
*.su
*.symtypes
+*.symversions
*.tab.[ch]
*.tar
*.xz
diff --git a/Makefile b/Makefile
index 240560e88d69..f27c0da5d05a 100644
--- a/Makefile
+++ b/Makefile
@@ -1831,7 +1831,8 @@ clean: $(clean-dirs)
-o -name '.tmp_*.o.*' \
-o -name '*.c.[012]*.*' \
-o -name '*.ll' \
- -o -name '*.gcno' \) -type f -print | xargs rm -f
+ -o -name '*.gcno' \
+ -o -name '*.*.symversions' \) -type f -print | xargs rm -f
# Generate tags for editors
# ---------------------------------------------------------------------------
diff --git a/arch/Kconfig b/arch/Kconfig
index a41fcb3ca7c6..736ae228e506 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -655,7 +655,6 @@ config LTO_CLANG
depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
depends on !KASAN
depends on !GCOV_KERNEL
- depends on !MODVERSIONS
select LTO
help
This option enables Clang's Link Time Optimization (LTO), which
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index ed74b2f986f7..eae2f5386a03 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -166,6 +166,15 @@ ifdef CONFIG_MODVERSIONS
# the actual value of the checksum generated by genksyms
# o remove .tmp_<file>.o to <file>.o
+ifdef CONFIG_LTO_CLANG
+# Generate .o.symversions files for each .o with exported symbols, and link these
+# to the kernel and/or modules at the end.
+cmd_modversions_c = \
+ if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \
+ $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
+ > $@.symversions; \
+ fi;
+else
cmd_modversions_c = \
if $(OBJDUMP) -h $@ | grep -q __ksymtab; then \
$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
@@ -177,6 +186,7 @@ cmd_modversions_c = \
rm -f $(@D)/.tmp_$(@F:.o=.ver); \
fi
endif
+endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
@@ -390,6 +400,18 @@ $(obj)/%.asn1.c $(obj)/%.asn1.h: $(src)/%.asn1 $(objtree)/scripts/asn1_compiler
$(subdir-builtin): $(obj)/%/built-in.a: $(obj)/% ;
$(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
+# combine symversions for later processing
+quiet_cmd_update_lto_symversions = SYMVER $@
+ifeq ($(CONFIG_LTO_CLANG) $(CONFIG_MODVERSIONS),y y)
+ cmd_update_lto_symversions = \
+ rm -f $@.symversions \
+ $(foreach n, $(filter-out FORCE,$^), \
+ $(if $(wildcard $(n).symversions), \
+ ; cat $(n).symversions >> $@.symversions))
+else
+ cmd_update_lto_symversions = echo >/dev/null
+endif
+
#
# Rule to compile a set of .o files into one .a file (without symbol table)
#
@@ -397,8 +419,11 @@ $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
quiet_cmd_ar_builtin = AR $@
cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
+quiet_cmd_ar_and_symver = AR $@
+ cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin)
+
$(obj)/built-in.a: $(real-obj-y) FORCE
- $(call if_changed,ar_builtin)
+ $(call if_changed,ar_and_symver)
#
# Rule to create modules.order file
@@ -418,8 +443,11 @@ $(obj)/modules.order: $(obj-m) FORCE
#
# Rule to compile a set of .o files into one .a file (with symbol table)
#
+quiet_cmd_ar_lib = AR $@
+ cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar)
+
$(obj)/lib.a: $(lib-y) FORCE
- $(call if_changed,ar)
+ $(call if_changed,ar_lib)
# NOTE:
# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
@@ -428,6 +456,7 @@ $(obj)/lib.a: $(lib-y) FORCE
ifdef CONFIG_LTO_CLANG
quiet_cmd_link_multi-m = AR [M] $@
cmd_link_multi-m = \
+ $(cmd_update_lto_symversions); \
rm -f $@; \
$(AR) cDPrsT $@ $(filter %.o,$^)
else
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 9ff8bfdb574d..066beffca09a 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -111,7 +111,11 @@ ifdef CONFIG_LTO_CLANG
prelink-ext := .lto
quiet_cmd_cc_lto_link_modules = LTO [M] $@
-cmd_cc_lto_link_modules = $(LD) $(ld_flags) -r -o $@ --whole-archive $^
+cmd_cc_lto_link_modules = \
+ $(LD) $(ld_flags) -r -o $@ \
+ $(shell [ -s $(@:.lto.o=.o.symversions) ] && \
+ echo -T $(@:.lto.o=.o.symversions)) \
+ --whole-archive $^
%.lto.o: %.o
$(call if_changed,cc_lto_link_modules)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 596507573a48..78e55fe7210b 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -43,11 +43,26 @@ info()
fi
}
+# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
+# .tmp_symversions.lds
+gen_symversions()
+{
+ info GEN .tmp_symversions.lds
+ rm -f .tmp_symversions.lds
+
+ for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
+ if [ -f ${o}.symversions ]; then
+ cat ${o}.symversions >> .tmp_symversions.lds
+ fi
+ done
+}
+
# Link of vmlinux.o used for section mismatch analysis
# ${1} output file
modpost_link()
{
local objects
+ local lds=""
objects="--whole-archive \
${KBUILD_VMLINUX_OBJS} \
@@ -57,6 +72,11 @@ modpost_link()
--end-group"
if [ -n "${CONFIG_LTO_CLANG}" ]; then
+ if [ -n "${CONFIG_MODVERSIONS}" ]; then
+ gen_symversions
+ lds="${lds} -T .tmp_symversions.lds"
+ fi
+
# This might take a while, so indicate that we're doing
# an LTO link
info LTO ${1}
@@ -64,7 +84,7 @@ modpost_link()
info LD ${1}
fi
- ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
+ ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
}
objtool_link()
@@ -242,6 +262,7 @@ cleanup()
{
rm -f .btf.*
rm -f .tmp_System.map
+ rm -f .tmp_symversions.lds
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
--
2.29.2.299.gdc1121823c-goog
next prev parent reply other threads:[~2020-11-18 22:07 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 22:07 [PATCH v7 00/17] Add support for Clang LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 01/17] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 02/17] kbuild: add support for Clang LTO Sami Tolvanen
2020-11-18 23:48 ` Nick Desaulniers
2020-11-20 16:23 ` Sami Tolvanen
2020-11-20 19:47 ` Kees Cook
2020-11-20 20:29 ` Nathan Chancellor
2020-11-20 20:43 ` Kees Cook
2020-11-20 20:58 ` Sami Tolvanen
2020-11-20 23:59 ` Kees Cook
2020-11-21 1:46 ` Sami Tolvanen
2020-11-21 20:11 ` Kees Cook
2020-11-18 22:07 ` Sami Tolvanen [this message]
2020-11-18 22:07 ` [PATCH v7 04/17] kbuild: lto: limit inlining Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 05/17] kbuild: lto: merge module sections Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 06/17] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 07/17] init: lto: ensure initcall ordering Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 08/17] init: lto: fix PREL32 relocations Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 09/17] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 10/17] modpost: lto: strip .lto from module names Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 11/17] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 12/17] efi/libstub: disable LTO Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 13/17] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 14/17] arm64: vdso: disable LTO Sami Tolvanen
2020-11-30 11:52 ` Will Deacon
2020-11-30 23:44 ` Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 15/17] KVM: arm64: disable LTO for the nVHE directory Sami Tolvanen
2020-11-23 10:21 ` David Brazdil
2020-11-23 18:34 ` Sami Tolvanen
2020-11-18 22:07 ` [PATCH v7 16/17] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-11-30 11:59 ` Will Deacon
2020-11-18 22:07 ` [PATCH v7 17/17] arm64: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-11-30 12:00 ` Will Deacon
2020-11-18 23:42 ` [PATCH v7 00/17] Add support for Clang LTO Nick Desaulniers
2020-11-20 10:29 ` Ard Biesheuvel
2020-11-20 20:19 ` Nick Desaulniers
2020-11-20 23:30 ` Ard Biesheuvel
2020-11-20 23:53 ` Nick Desaulniers
2020-11-21 7:35 ` Ard Biesheuvel
2020-11-21 11:40 ` Marc Zyngier
2020-11-21 3:14 ` Nathan Chancellor
2020-11-20 4:04 ` Josh Poimboeuf
2020-11-20 20:25 ` Sami Tolvanen
2020-11-30 12:01 ` Will Deacon
2020-12-01 17:31 ` Kees Cook
2020-12-01 19:51 ` Nick Desaulniers
2020-12-01 21:38 ` Sami Tolvanen
2020-12-02 2:42 ` Masahiro Yamada
2020-12-02 5:46 ` Sami Tolvanen
2020-12-02 18:54 ` Kees Cook
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