Message ID | 20200115204648.7179-1-alex@ghiti.fr (mailing list archive) |
---|---|
State | Changes Requested |
Headers | show |
Series | powerpc: Do not consider weak unresolved symbol relocations as bad | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (20862247a368dbb75d6e97d82345999adaacf3cc) |
snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
snowpatch_ozlabs/build-ppc64be | fail | build failed! |
snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 69 lines checked |
snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
Hi Alexandre, Thanks for sorting this out. Just a few comments below. On Wed, 15 Jan 2020 15:46:48 -0500 Alexandre Ghiti <alex@ghiti.fr> wrote: > > > # Have Kbuild supply the path to objdump so we handle cross compilation. ^ "and nm" > +# Remove from the bad relocations those that match an undefined weak symbol > +# which will result in an absolute relocation to 0. > +# Weak unresolved symbols are of that form in nm output: > +# " w _binary__btf_vmlinux_bin_end" > +undef_weak_symbols=$($nm "$vmlinux" | awk -e '$1 ~ /w/ { print $2 }') > + > +while IFS= read -r weak_symbol; do > + bad_relocs="$(echo -n "$bad_relocs" | sed "/$weak_symbol/d")" > +done <<< "$undef_weak_symbols" This is not a bash script, and the above is a bashism :-( Also, my version of awk (mawk) doesn't have a -e option. How about something like : undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }') if [ "$undef_weak_symbols" ]; then bad_relocs="$(echo "$bad_relocs" | grep -F -w -v "$undef_weak_symbols")" fi Or do this near the top and add the grep to the others.
Hi Stephen, On 1/15/20 6:39 PM, Stephen Rothwell wrote: > Hi Alexandre, > > Thanks for sorting this out. Just a few comments below. > > On Wed, 15 Jan 2020 15:46:48 -0500 Alexandre Ghiti <alex@ghiti.fr> wrote: >> >> # Have Kbuild supply the path to objdump so we handle cross compilation. > ^ > "and nm" > >> +# Remove from the bad relocations those that match an undefined weak symbol >> +# which will result in an absolute relocation to 0. >> +# Weak unresolved symbols are of that form in nm output: >> +# " w _binary__btf_vmlinux_bin_end" >> +undef_weak_symbols=$($nm "$vmlinux" | awk -e '$1 ~ /w/ { print $2 }') >> + >> +while IFS= read -r weak_symbol; do >> + bad_relocs="$(echo -n "$bad_relocs" | sed "/$weak_symbol/d")" >> +done <<< "$undef_weak_symbols" > This is not a bash script, and the above is a bashism :-( > Also, my version of awk (mawk) doesn't have a -e option. > > How about something like : > > undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }') > if [ "$undef_weak_symbols" ]; then > bad_relocs="$(echo "$bad_relocs" | grep -F -w -v "$undef_weak_symbols")" > fi > > Or do this near the top and add the grep to the others. Yes that's quite better, thanks, I'll send a new version tomorrow. Thanks again, Alex
diff --git a/arch/powerpc/Makefile.postlink b/arch/powerpc/Makefile.postlink index 134f12f89b92..2268396ff4bb 100644 --- a/arch/powerpc/Makefile.postlink +++ b/arch/powerpc/Makefile.postlink @@ -17,11 +17,11 @@ quiet_cmd_head_check = CHKHEAD $@ quiet_cmd_relocs_check = CHKREL $@ ifdef CONFIG_PPC_BOOK3S_64 cmd_relocs_check = \ - $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/relocs_check.sh "$(OBJDUMP)" "$@" ; \ + $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@" ; \ $(BASH) $(srctree)/arch/powerpc/tools/unrel_branch_check.sh "$(OBJDUMP)" "$@" else cmd_relocs_check = \ - $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/relocs_check.sh "$(OBJDUMP)" "$@" + $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@" endif # `@true` prevents complaint when there is nothing to be done diff --git a/arch/powerpc/tools/relocs_check.sh b/arch/powerpc/tools/relocs_check.sh index 7b9fe0a567cf..783281b75d9d 100755 --- a/arch/powerpc/tools/relocs_check.sh +++ b/arch/powerpc/tools/relocs_check.sh @@ -10,14 +10,15 @@ # based on relocs_check.pl # Copyright © 2009 IBM Corporation -if [ $# -lt 2 ]; then - echo "$0 [path to objdump] [path to vmlinux]" 1>&2 +if [ $# -lt 3 ]; then + echo "$0 [path to objdump] [path to nm] [path to vmlinux]" 1>&2 exit 1 fi # Have Kbuild supply the path to objdump so we handle cross compilation. objdump="$1" -vmlinux="$2" +nm="$2" +vmlinux="$3" bad_relocs=$( $objdump -R "$vmlinux" | @@ -26,8 +27,6 @@ $objdump -R "$vmlinux" | # These relocations are okay # On PPC64: # R_PPC64_RELATIVE, R_PPC64_NONE - # R_PPC64_ADDR64 mach_<name> - # R_PPC64_ADDR64 __crc_<name> # On PPC: # R_PPC_RELATIVE, R_PPC_ADDR16_HI, # R_PPC_ADDR16_HA,R_PPC_ADDR16_LO, @@ -38,15 +37,27 @@ R_PPC_ADDR16_LO R_PPC_ADDR16_HI R_PPC_ADDR16_HA R_PPC_RELATIVE -R_PPC_NONE' | - grep -E -v '\<R_PPC64_ADDR64[[:space:]]+mach_' | - grep -E -v '\<R_PPC64_ADDR64[[:space:]]+__crc_' +R_PPC_NONE' ) if [ -z "$bad_relocs" ]; then exit 0 fi +# Remove from the bad relocations those that match an undefined weak symbol +# which will result in an absolute relocation to 0. +# Weak unresolved symbols are of that form in nm output: +# " w _binary__btf_vmlinux_bin_end" +undef_weak_symbols=$($nm "$vmlinux" | awk -e '$1 ~ /w/ { print $2 }') + +while IFS= read -r weak_symbol; do + bad_relocs="$(echo -n "$bad_relocs" | sed "/$weak_symbol/d")" +done <<< "$undef_weak_symbols" + +if [ -z "$bad_relocs" ]; then + exit 0 +fi + num_bad=$(echo "$bad_relocs" | wc -l) echo "WARNING: $num_bad bad relocations" echo "$bad_relocs"
Commit 8580ac9404f6 ("bpf: Process in-kernel BTF") introduced two weak symbols that may be unresolved at link time which result in an absolute relocation to 0. relocs_check.sh emits the following warning: "WARNING: 2 bad relocations c000000001a41478 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_start c000000001a41480 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_end" whereas those relocations are legitimate even for a relocatable kernel compiled with -pie option. relocs_check.sh already excluded some weak unresolved symbols explicitly: remove those hardcoded symbols and add some logic that parses the symbols using nm, retrieves all the weak unresolved symbols and excludes those from the list of the potential bad relocations. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> --- arch/powerpc/Makefile.postlink | 4 ++-- arch/powerpc/tools/relocs_check.sh | 27 +++++++++++++++++++-------- 2 files changed, 21 insertions(+), 10 deletions(-)