Makefile | 3 ++- scripts/tools-support-relr.sh | 8 ++++++-- 2 files changed, 8 insertions(+), 3 deletions(-)
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, try -z pack-relative-relocs, which is supported since LLD 15.
Keep supporting --pack-dyn-relocs=relr as well for older LLD versions.
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 | 3 ++-
scripts/tools-support-relr.sh | 8 ++++++--
2 files changed, 8 insertions(+), 3 deletions(-)
---
Changes from v1:
* Keep supporting --pack-dyn-relocs=relr for older ld.lld versions
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..4c121946e517 100755
--- a/scripts/tools-support-relr.sh
+++ b/scripts/tools-support-relr.sh
@@ -7,8 +7,12 @@ 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.
+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 $tmp_file 2>&1 |
+ grep -q pack-relative-relocs && exit 1
+fi
# Despite printing an error message, GNU nm still exits with exit code 0 if it
# sees a relr section. So we need to check that nothing is printed to stderr.
--
2.40.0.348.gf938b09366-goog
On Fri, Mar 24, 2023 at 2:22 PM Fangrui Song <maskray@google.com> wrote: > > Commit 27f2a4db76e8 ("Makefile: fix GDB warning with CONFIG_RELR") > added --use-android-relr-tags to fix a GDB warning > > BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn' > > The GDB warning has been fixed in version 11.2. > > The DT_ANDROID_RELR tag was deprecated since DT_RELR was standardized. > Thus, --use-android-relr-tags should be removed. While making the > change, try -z pack-relative-relocs, which is supported since LLD 15. > Keep supporting --pack-dyn-relocs=relr as well for older LLD versions. > > As of today, GNU ld supports the latter option for x86 and powerpc64 > ports and has no intention to support --pack-dyn-relocs=relr. In the > absence of the glibc symbol version GLIBC_ABI_DT_RELR, > --pack-dyn-relocs=relr and -z pack-relative-relocs are identical in > ld.lld. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1057 > Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=a619b58721f0a03fd91c27670d3e4c2fb0d88f1e > Signed-off-by: Fangrui Song <maskray@google.com> Thanks v2 looks better. IIUC, this will first try to test+use `--pack-dyn-relocs=relr` in preference to `-z pack-relative-relocs`. Do we want to reorder the preference, for both the test and actual flag used? > --- > Makefile | 3 ++- > scripts/tools-support-relr.sh | 8 ++++++-- > 2 files changed, 8 insertions(+), 3 deletions(-) > --- > Changes from v1: > * Keep supporting --pack-dyn-relocs=relr for older ld.lld versions > > diff --git a/Makefile b/Makefile > index a2c310df2145..e23a85476d5d 100644 > --- a/Makefile > +++ b/Makefile > @@ -1113,7 +1113,8 @@ LDFLAGS_vmlinux += -X > endif > > ifeq ($(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..4c121946e517 100755 > --- a/scripts/tools-support-relr.sh > +++ b/scripts/tools-support-relr.sh > @@ -7,8 +7,12 @@ 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. > +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 > > # 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 > -- Thanks, ~Nick Desaulniers
On Fri, Apr 7, 2023 at 11:35 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Fri, Mar 24, 2023 at 2:22 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, try -z pack-relative-relocs, which is supported since LLD 15. > > Keep supporting --pack-dyn-relocs=relr as well for older LLD versions. > > > > 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> > > Thanks v2 looks better. IIUC, this will first try to test+use > `--pack-dyn-relocs=relr` in preference to `-z pack-relative-relocs`. > Do we want to reorder the preference, for both the test and actual > flag used? Thanks for the comment. The order is deliberate and there is no obsolescence indication of --pack-dyn-relocs=relr. GNU ld and newer lld report warnings (instead of errors) for unknown -z options, and only errors lead to non-zero exit codes. Therefore, $(call ld-option,--pack-dyn-relocs=relr,-z pack-relative-relocs) has to place --pack-dyn-relocs=relr first. scripts/tools-support-relr.sh has to test --pack-dyn-relocs=relr first as well. > > --- > > Makefile | 3 ++- > > scripts/tools-support-relr.sh | 8 ++++++-- > > 2 files changed, 8 insertions(+), 3 deletions(-) > > --- > > Changes from v1: > > * Keep supporting --pack-dyn-relocs=relr for older ld.lld versions > > > > diff --git a/Makefile b/Makefile > > index a2c310df2145..e23a85476d5d 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -1113,7 +1113,8 @@ LDFLAGS_vmlinux += -X > > endif > > > > ifeq ($(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..4c121946e517 100755 > > --- a/scripts/tools-support-relr.sh > > +++ b/scripts/tools-support-relr.sh > > @@ -7,8 +7,12 @@ 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. > > +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 > > > > # 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 > > > > > -- > Thanks, > ~Nick Desaulniers -- 宋方睿
On Tue, Apr 11, 2023 at 11:44 AM Fangrui Song <maskray@google.com> wrote: > > On Fri, Apr 7, 2023 at 11:35 AM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > On Fri, Mar 24, 2023 at 2:22 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, try -z pack-relative-relocs, which is supported since LLD 15. > > > Keep supporting --pack-dyn-relocs=relr as well for older LLD versions. > > > > > > 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> > > > > Thanks v2 looks better. IIUC, this will first try to test+use > > `--pack-dyn-relocs=relr` in preference to `-z pack-relative-relocs`. > > Do we want to reorder the preference, for both the test and actual > > flag used? > > Thanks for the comment. The order is deliberate and there is no > obsolescence indication of --pack-dyn-relocs=relr. > > GNU ld and newer lld report warnings (instead of errors) for unknown > -z options, and only errors lead to non-zero exit codes. That makes sense; consider adding a note about that intention to the commit message in a v3 along with: Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > Therefore, $(call ld-option,--pack-dyn-relocs=relr,-z > pack-relative-relocs) has to place --pack-dyn-relocs=relr first. > scripts/tools-support-relr.sh has to test --pack-dyn-relocs=relr first as well. > > > > --- > > > Makefile | 3 ++- > > > scripts/tools-support-relr.sh | 8 ++++++-- > > > 2 files changed, 8 insertions(+), 3 deletions(-) > > > --- > > > Changes from v1: > > > * Keep supporting --pack-dyn-relocs=relr for older ld.lld versions > > > > > > diff --git a/Makefile b/Makefile > > > index a2c310df2145..e23a85476d5d 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -1113,7 +1113,8 @@ LDFLAGS_vmlinux += -X > > > endif > > > > > > ifeq ($(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..4c121946e517 100755 > > > --- a/scripts/tools-support-relr.sh > > > +++ b/scripts/tools-support-relr.sh > > > @@ -7,8 +7,12 @@ 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. > > > +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 > > > > > > # 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 > > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers > > > > -- > 宋方睿 -- Thanks, ~Nick Desaulniers
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