| Message ID | 20230323204427.3594372-1-maskray@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Makefile: use -z pack-relative-relocs | expand |
Hi Fangrui, Thanks for the patches! On Thu, Mar 23, 2023 at 1:44 PM Fangrui Song <maskray@google.com> wrote: > > Commit 27f2a4db76e8 ("Makefile: fix GDB warning with CONFIG_RELR") > added --use-android-relr-tags to fix a GDB warning > > BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn' > > The GDB warning has been fixed in version 11.2. > > The DT_ANDROID_RELR tag was deprecated since DT_RELR was standardized. > Thus, --use-android-relr-tags should be removed. While making the > change, replace --pack-dyn-relocs=relr with -z pack-relative-relocs, > which is supported since LLD 15. Looks like commit 4a8de2832a2a ("[ELF] Add -z pack-relative-relocs") > > As of today, GNU ld supports the latter option for x86 and powerpc64 > ports and has no intention to support --pack-dyn-relocs=relr. In the > absence of the glibc symbol version GLIBC_ABI_DT_RELR, > --pack-dyn-relocs=relr and -z pack-relative-relocs are identical in > ld.lld. Won't this regress support for CONFIG_TOOLS_SUPPORT_RELR for LLD 11-14? (which we still support, see Documentation/process/changes.rst; I guess we don't list LLD explicitly, but it's effectively under the llvm umbrella there). IIUC, looks like lld 7.0+ should support SHT_RELR based on looking at commit 11479daf2f06 ("lld: add experimental support for SHT_RELR sections.") So we might want to invoke the linker twice, once with the new flag, and again with the old if we fail the first time? > > Link: https://github.com/ClangBuiltLinux/linux/issues/1057 > Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=a619b58721f0a03fd91c27670d3e4c2fb0d88f1e > Signed-off-by: Fangrui Song <maskray@google.com> > --- > Makefile | 2 +- > scripts/tools-support-relr.sh | 3 +-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/Makefile b/Makefile > index a2c310df2145..30c2edc35813 100644 > --- a/Makefile > +++ b/Makefile > @@ -1113,7 +1113,7 @@ LDFLAGS_vmlinux += -X > endif > > ifeq ($(CONFIG_RELR),y) > -LDFLAGS_vmlinux += --pack-dyn-relocs=relr --use-android-relr-tags > +LDFLAGS_vmlinux += -z pack-relative-relocs > endif > > # We never want expected sections to be placed heuristically by the > diff --git a/scripts/tools-support-relr.sh b/scripts/tools-support-relr.sh > index cb55878bd5b8..58c2e8b02ce8 100755 > --- a/scripts/tools-support-relr.sh > +++ b/scripts/tools-support-relr.sh > @@ -7,8 +7,7 @@ trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT > cat << "END" | $CC -c -x c - -o $tmp_file.o >/dev/null 2>&1 > void *p = &p; > END > -$LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr \ > - --use-android-relr-tags -o $tmp_file > +$LD $tmp_file.o -shared -Bsymbolic -z pack-relative-relocs -o $tmp_file > > # Despite printing an error message, GNU nm still exits with exit code 0 if it > # sees a relr section. So we need to check that nothing is printed to stderr. > -- > 2.40.0.348.gf938b09366-goog >
On 2023-03-23, Nick Desaulniers wrote: >Hi Fangrui, >Thanks for the patches! > >On Thu, Mar 23, 2023 at 1:44 PM Fangrui Song <maskray@google.com> wrote: >> >> Commit 27f2a4db76e8 ("Makefile: fix GDB warning with CONFIG_RELR") >> added --use-android-relr-tags to fix a GDB warning >> >> BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn' >> >> The GDB warning has been fixed in version 11.2. >> >> The DT_ANDROID_RELR tag was deprecated since DT_RELR was standardized. >> Thus, --use-android-relr-tags should be removed. While making the >> change, replace --pack-dyn-relocs=relr with -z pack-relative-relocs, >> which is supported since LLD 15. > >Looks like >commit 4a8de2832a2a ("[ELF] Add -z pack-relative-relocs") > >> >> As of today, GNU ld supports the latter option for x86 and powerpc64 >> ports and has no intention to support --pack-dyn-relocs=relr. In the >> absence of the glibc symbol version GLIBC_ABI_DT_RELR, >> --pack-dyn-relocs=relr and -z pack-relative-relocs are identical in >> ld.lld. > >Won't this regress support for CONFIG_TOOLS_SUPPORT_RELR for LLD >11-14? (which we still support, see Documentation/process/changes.rst; >I guess we don't list LLD explicitly, but it's effectively under the >llvm umbrella there). > >IIUC, looks like lld 7.0+ should support SHT_RELR based on looking at >commit 11479daf2f06 ("lld: add experimental support for SHT_RELR sections.") > >So we might want to invoke the linker twice, once with the new flag, >and again with the old if we fail the first time? Yes, I am aware of the increased linker and debugger requirement and was thinking the CONFIG_RELR=y case with ld.lld<15 did not matter. Since you raised this, it seems that we should ld.lld<15. How about the following diff? diff --git a/Makefile b/Makefile index a2c310df2145..e23a85476d5d 100644 --- a/Makefile +++ b/Makefile @@ -1113,7 +1113,8 @@ LDFLAGS_vmlinux += -X endif ifeq ($(CONFIG_RELR),y) -LDFLAGS_vmlinux += --pack-dyn-relocs=relr --use-android-relr-tags +# ld.lld before 15 did not support -z pack-relative-relocs. +LDFLAGS_vmlinux += $(call ld-option,--pack-dyn-relocs=relr,-z pack-relative-relocs) endif # We never want expected sections to be placed heuristically by the diff --git a/scripts/tools-support-relr.sh b/scripts/tools-support-relr.sh index cb55878bd5b8..355a9b1eb150 100755 --- a/scripts/tools-support-relr.sh +++ b/scripts/tools-support-relr.sh @@ -7,8 +7,9 @@ trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT cat << "END" | $CC -c -x c - -o $tmp_file.o >/dev/null 2>&1 void *p = &p; END -$LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr \ - --use-android-relr-tags -o $tmp_file +# ld.lld before 15 did not support -z pack-relative-relocs. +$LD $tmp_file.o -shared -Bsymbolic -z pack-relative-relocs -o $tmp_file || \ + $LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr -o $tmp_file # Despite printing an error message, GNU nm still exits with exit code 0 if it # sees a relr section. So we need to check that nothing is printed to stderr.
Hi Fangrui,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on masahiroy-kbuild/for-next]
[also build test WARNING on masahiroy-kbuild/fixes linus/master v6.3-rc3 next-20230323]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Fangrui-Song/Makefile-use-z-pack-relative-relocs/20230324-044515
base: https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
patch link: https://lore.kernel.org/r/20230323204427.3594372-1-maskray%40google.com
patch subject: [PATCH] Makefile: use -z pack-relative-relocs
config: arm64-randconfig-r022-20230322 (https://download.01.org/0day-ci/archive/20230324/202303241443.0sSziFDY-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/8f47a36faf182f96a2bbf4d3b9305fe9a90c5cde
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Fangrui-Song/Makefile-use-z-pack-relative-relocs/20230324-044515
git checkout 8f47a36faf182f96a2bbf4d3b9305fe9a90c5cde
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303241443.0sSziFDY-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> aarch64-linux-ld: warning: -z pack-relative-relocs ignored
>> aarch64-linux-ld: warning: -z pack-relative-relocs ignored
>> aarch64-linux-ld: warning: -z pack-relative-relocs ignored
On Thu, Mar 23, 2023 at 11:51 PM kernel test robot <lkp@intel.com> wrote: > > Hi Fangrui, > > Thank you for the patch! Perhaps something to improve: > > [auto build test WARNING on masahiroy-kbuild/for-next] > [also build test WARNING on masahiroy-kbuild/fixes linus/master v6.3-rc3 next-20230323] > [If your patch is applied to the wrong git tree, kindly drop us a note. > And when submitting patch, we suggest to use '--base' as documented in > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Fangrui-Song/Makefile-use-z-pack-relative-relocs/20230324-044515 > base: https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next > patch link: https://lore.kernel.org/r/20230323204427.3594372-1-maskray%40google.com > patch subject: [PATCH] Makefile: use -z pack-relative-relocs > config: arm64-randconfig-r022-20230322 (https://download.01.org/0day-ci/archive/20230324/202303241443.0sSziFDY-lkp@intel.com/config) > compiler: aarch64-linux-gcc (GCC) 12.1.0 > reproduce (this is a W=1 build): > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > # https://github.com/intel-lab-lkp/linux/commit/8f47a36faf182f96a2bbf4d3b9305fe9a90c5cde > git remote add linux-review https://github.com/intel-lab-lkp/linux > git fetch --no-tags linux-review Fangrui-Song/Makefile-use-z-pack-relative-relocs/20230324-044515 > git checkout 8f47a36faf182f96a2bbf4d3b9305fe9a90c5cde > # save the config file > mkdir build_dir && cp config build_dir/.config > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 olddefconfig > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash > > If you fix the issue, kindly add following tag where applicable > | Reported-by: kernel test robot <lkp@intel.com> > | Link: https://lore.kernel.org/oe-kbuild-all/202303241443.0sSziFDY-lkp@intel.com/ > > All warnings (new ones prefixed by >>): > > >> aarch64-linux-ld: warning: -z pack-relative-relocs ignored > >> aarch64-linux-ld: warning: -z pack-relative-relocs ignored > >> aarch64-linux-ld: warning: -z pack-relative-relocs ignored > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests I forgot to check aarch64-linux-gnu-ld. To address the issue I can use: # ld.lld before 15 did not support -z pack-relative-relocs. if ! $LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr -o $tmp_file 2>/dev/null; then $LD $tmp_file.o -shared -Bsymbolic -z pack-relative-relocs -o $tmp_file 2>&1 | grep -q pack-relative-relocs && exit 1 fi
diff --git a/Makefile b/Makefile index a2c310df2145..30c2edc35813 100644 --- a/Makefile +++ b/Makefile @@ -1113,7 +1113,7 @@ LDFLAGS_vmlinux += -X endif ifeq ($(CONFIG_RELR),y) -LDFLAGS_vmlinux += --pack-dyn-relocs=relr --use-android-relr-tags +LDFLAGS_vmlinux += -z pack-relative-relocs endif # We never want expected sections to be placed heuristically by the diff --git a/scripts/tools-support-relr.sh b/scripts/tools-support-relr.sh index cb55878bd5b8..58c2e8b02ce8 100755 --- a/scripts/tools-support-relr.sh +++ b/scripts/tools-support-relr.sh @@ -7,8 +7,7 @@ trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT cat << "END" | $CC -c -x c - -o $tmp_file.o >/dev/null 2>&1 void *p = &p; END -$LD $tmp_file.o -shared -Bsymbolic --pack-dyn-relocs=relr \ - --use-android-relr-tags -o $tmp_file +$LD $tmp_file.o -shared -Bsymbolic -z pack-relative-relocs -o $tmp_file # Despite printing an error message, GNU nm still exits with exit code 0 if it # sees a relr section. So we need to check that nothing is printed to stderr.
Commit 27f2a4db76e8 ("Makefile: fix GDB warning with CONFIG_RELR") added --use-android-relr-tags to fix a GDB warning BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn' The GDB warning has been fixed in version 11.2. The DT_ANDROID_RELR tag was deprecated since DT_RELR was standardized. Thus, --use-android-relr-tags should be removed. While making the change, replace --pack-dyn-relocs=relr with -z pack-relative-relocs, which is supported since LLD 15. As of today, GNU ld supports the latter option for x86 and powerpc64 ports and has no intention to support --pack-dyn-relocs=relr. In the absence of the glibc symbol version GLIBC_ABI_DT_RELR, --pack-dyn-relocs=relr and -z pack-relative-relocs are identical in ld.lld. Link: https://github.com/ClangBuiltLinux/linux/issues/1057 Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=a619b58721f0a03fd91c27670d3e4c2fb0d88f1e Signed-off-by: Fangrui Song <maskray@google.com> --- Makefile | 2 +- scripts/tools-support-relr.sh | 3 +-- 2 files changed, 2 insertions(+), 3 deletions(-)