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 v8 03/16] kbuild: lto: fix module versioning
Date: Tue, 1 Dec 2020 13:36:54 -0800 [thread overview]
Message-ID: <20201201213707.541432-4-samitolvanen@google.com> (raw)
In-Reply-To: <20201201213707.541432-1-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 f5cac2428efc..222ae96d179d 100644
--- a/Makefile
+++ b/Makefile
@@ -1829,7 +1829,8 @@ 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 30907b554451..c3c13ec9a74c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -633,7 +633,6 @@ config HAS_LTO_CLANG
depends on !FTRACE_MCOUNT_USE_RECORDMCOUNT
depends on !KASAN
depends on !GCOV_KERNEL
- depends on !MODVERSIONS
help
The compiler and Kconfig options support building with Clang's
LTO.
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
--
2.29.2.576.ga3fc446d84-goog
next prev parent reply other threads:[~2020-12-01 21:39 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 21:36 [PATCH v8 00/16] Add support for Clang LTO Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 01/16] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-12-01 21:47 ` Steven Rostedt
2020-12-01 21:36 ` [PATCH v8 02/16] kbuild: add support for Clang LTO Sami Tolvanen
2020-12-02 2:59 ` Masahiro Yamada
2020-12-03 0:07 ` Nick Desaulniers
2020-12-01 21:36 ` Sami Tolvanen [this message]
2020-12-01 21:36 ` [PATCH v8 04/16] kbuild: lto: limit inlining Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 05/16] kbuild: lto: merge module sections Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 06/16] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 07/16] init: lto: ensure initcall ordering Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 08/16] init: lto: fix PREL32 relocations Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 09/16] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 10/16] modpost: lto: strip .lto from module names Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 11/16] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 12/16] efi/libstub: disable LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 13/16] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 14/16] arm64: vdso: disable LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 15/16] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 16/16] arm64: allow LTO to be selected Sami Tolvanen
2020-12-03 0:01 ` [PATCH v8 00/16] Add support for Clang LTO Nick Desaulniers
2020-12-03 11:26 ` Will Deacon
2020-12-03 17:07 ` Sami Tolvanen
2020-12-03 18:21 ` Nathan Chancellor
2020-12-03 18:22 ` Will Deacon
2020-12-03 22:32 ` Nick Desaulniers
2020-12-04 9:35 ` Will Deacon
2020-12-04 22:52 ` Sami Tolvanen
2020-12-06 6:50 ` Nathan Chancellor
2020-12-06 20:09 ` Sami Tolvanen
2020-12-08 0:46 ` Nathan Chancellor
2020-12-08 12:15 ` Arnd Bergmann
2020-12-08 13:54 ` Arnd Bergmann
2020-12-08 16:53 ` Sami Tolvanen
2020-12-08 16:56 ` Arnd Bergmann
2020-12-08 16:43 ` Sami Tolvanen
[not found] ` <CAK8P3a1Xfpt7QLkvxjtXKcgzcWkS8g9bmxD687+rqjTafTzKrg@mail.gmail.com>
2020-12-08 21:09 ` Nick Desaulniers
2020-12-08 22:20 ` Arnd Bergmann
2020-12-09 16:11 ` Sami Tolvanen
[not found] ` <CAK8P3a3O65m6Us=YvCP3QA+0kqAeEqfi-DLOJa+JYmBqs8-JcA@mail.gmail.com>
2020-12-09 5:23 ` Fāng-ruì Sòng
2020-12-09 9:07 ` Arnd Bergmann
2020-12-09 16:09 ` Sami Tolvanen
2020-12-09 19:24 ` Arnd Bergmann
2020-12-09 4:55 ` Fangrui Song
2020-12-09 9:19 ` Arnd Bergmann
2020-12-09 12:35 ` Arnd Bergmann
2020-12-09 16:25 ` Sami Tolvanen
2020-12-09 17:51 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201201213707.541432-4-samitolvanen@google.com \
--to=samitolvanen@google.com \
--cc=clang-built-linux@googlegroups.com \
--cc=gregkh@linuxfoundation.org \
--cc=jpoimboe@redhat.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=ndesaulniers@google.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).