| Message ID | 20240716105753.524866-1-adhemerval.zanella@linaro.org |
|---|---|
| State | Accepted |
| Commit | 4f047d9edecb1a9b796a9a904dcd42bd3cc3d3b6 |
| Headers | show |
| Series | [v2] elf: Fix localplt.awk for DT_RELR-enabled builds (BZ 31978) | expand |
Ping, I think we should fix it for 2.40. On 16/07/24 07:57, Adhemerval Zanella wrote: > For each input readelf output, localplt.awk parses each 'Relocation > section' entry, checks its offset against the dynamic section entry, and > saves each DT_JMPREL, DT_RELA, and DT_REL offset value it finds. After > all lines are read, the script checks if any segment offset differed > from 0, meaning at least one 'Relocation section' was matched. > > However, if the shared object was built with RELR support and the static > linker could place all the relocation on DT_RELR, there would be no > DT_JMPREL, DT_RELA, and DT_REL entries; only a DT_RELR. > > For the current three ABIs that support (aarch64, x86, and powerpc64), > the powerpc64 ld.so shows the behavior above. Both x86_64 and aarch64 > show extra relocations on '.rela.dyn', which makes the script check to > succeed. > > This patch fixes by handling DT_RELR, where the offset is checked > against the dynamic section entries and if the shared object contains an > entry it means that there are no extra PLT entries (since all > relocations are relative). > > It fixes the elf/check-localplt failure on powerpc. > > Checked with a build/check for aarch64-linux-gnu, x86_64-linux-gnu, > i686-linux-gnu, arm-linux-gnueabihf, s390x-linux-gnu, powerpc-linux-gnu, > powerpc64-linux-gnu, and powerpc64le-linux-gnu. > --- > scripts/localplt.awk | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/scripts/localplt.awk b/scripts/localplt.awk > index fe79ca01ab..621ae7d8e8 100644 > --- a/scripts/localplt.awk > +++ b/scripts/localplt.awk > @@ -10,7 +10,8 @@ BEGIN { > } > > FILENAME != lastfile { > - if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) { > + if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0 \ > + && relr_offset == 0) { > print FILENAME ": *** failed to find expected output (readelf -WSdr)"; > result = 2; > } > @@ -22,6 +23,7 @@ FILENAME != lastfile { > jmprel_offset = 0; > rela_offset = 0; > rel_offset = 0; > + relr_offset = 0; > pltrelsz = -1; > delete section_offset_by_address; > } > @@ -77,6 +79,8 @@ in_relocs && relocs_offset == rel_offset && NF >= 5 { > } > } > > +# No need to handle DT_RELR (all packed relocations are relative). > + > in_relocs { next } > > $1 == "Relocation" && $2 == "section" && $5 == "offset" { > @@ -121,4 +125,14 @@ $2 == "(REL)" { > } > next > } > + > +$2 == "(RELR)" { > + relr_addr = strtonum($3); > + if (relr_addr in section_offset_by_address) { > + relr_offset = section_offset_by_address[relr_addr]; > + } else { > + print FILENAME ": *** DT_RELR does not match any section's address"; > + result = 2; > + } > +} > END { exit(result) }
Yes, OK with someone's R-B Am Donnerstag, 18. Juli 2024, 14:17:11 CEST schrieb Adhemerval Zanella Netto: > Ping, I think we should fix it for 2.40. > > On 16/07/24 07:57, Adhemerval Zanella wrote: > > For each input readelf output, localplt.awk parses each 'Relocation > > section' entry, checks its offset against the dynamic section entry, and > > saves each DT_JMPREL, DT_RELA, and DT_REL offset value it finds. After > > all lines are read, the script checks if any segment offset differed > > from 0, meaning at least one 'Relocation section' was matched. > > > > However, if the shared object was built with RELR support and the static > > linker could place all the relocation on DT_RELR, there would be no > > DT_JMPREL, DT_RELA, and DT_REL entries; only a DT_RELR. > > > > For the current three ABIs that support (aarch64, x86, and powerpc64), > > the powerpc64 ld.so shows the behavior above. Both x86_64 and aarch64 > > show extra relocations on '.rela.dyn', which makes the script check to > > succeed. > > > > This patch fixes by handling DT_RELR, where the offset is checked > > against the dynamic section entries and if the shared object contains an > > entry it means that there are no extra PLT entries (since all > > relocations are relative). > > > > It fixes the elf/check-localplt failure on powerpc. > > > > Checked with a build/check for aarch64-linux-gnu, x86_64-linux-gnu, > > i686-linux-gnu, arm-linux-gnueabihf, s390x-linux-gnu, powerpc-linux-gnu, > > powerpc64-linux-gnu, and powerpc64le-linux-gnu. > > --- > > scripts/localplt.awk | 16 +++++++++++++++- > > 1 file changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/scripts/localplt.awk b/scripts/localplt.awk > > index fe79ca01ab..621ae7d8e8 100644 > > --- a/scripts/localplt.awk > > +++ b/scripts/localplt.awk > > @@ -10,7 +10,8 @@ BEGIN { > > } > > > > FILENAME != lastfile { > > - if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) { > > + if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0 \ > > + && relr_offset == 0) { > > print FILENAME ": *** failed to find expected output (readelf -WSdr)"; > > result = 2; > > } > > @@ -22,6 +23,7 @@ FILENAME != lastfile { > > jmprel_offset = 0; > > rela_offset = 0; > > rel_offset = 0; > > + relr_offset = 0; > > pltrelsz = -1; > > delete section_offset_by_address; > > } > > @@ -77,6 +79,8 @@ in_relocs && relocs_offset == rel_offset && NF >= 5 { > > } > > } > > > > +# No need to handle DT_RELR (all packed relocations are relative). > > + > > in_relocs { next } > > > > $1 == "Relocation" && $2 == "section" && $5 == "offset" { > > @@ -121,4 +125,14 @@ $2 == "(REL)" { > > } > > next > > } > > + > > +$2 == "(RELR)" { > > + relr_addr = strtonum($3); > > + if (relr_addr in section_offset_by_address) { > > + relr_offset = section_offset_by_address[relr_addr]; > > + } else { > > + print FILENAME ": *** DT_RELR does not match any section's address"; > > + result = 2; > > + } > > +} > > END { exit(result) } >
On 7/16/24 6:57 AM, Adhemerval Zanella wrote: > For each input readelf output, localplt.awk parses each 'Relocation > section' entry, checks its offset against the dynamic section entry, and > saves each DT_JMPREL, DT_RELA, and DT_REL offset value it finds. After > all lines are read, the script checks if any segment offset differed > from 0, meaning at least one 'Relocation section' was matched. > > However, if the shared object was built with RELR support and the static > linker could place all the relocation on DT_RELR, there would be no > DT_JMPREL, DT_RELA, and DT_REL entries; only a DT_RELR. Agreed, as is the case in ppc64le today. > > For the current three ABIs that support (aarch64, x86, and powerpc64), > the powerpc64 ld.so shows the behavior above. Both x86_64 and aarch64 > show extra relocations on '.rela.dyn', which makes the script check to > succeed. > > This patch fixes by handling DT_RELR, where the offset is checked > against the dynamic section entries and if the shared object contains an > entry it means that there are no extra PLT entries (since all > relocations are relative). > > It fixes the elf/check-localplt failure on powerpc. > > Checked with a build/check for aarch64-linux-gnu, x86_64-linux-gnu, > i686-linux-gnu, arm-linux-gnueabihf, s390x-linux-gnu, powerpc-linux-gnu, > powerpc64-linux-gnu, and powerpc64le-linux-gnu. LGTM. Nice to add full DT_RELR support for this. Reviewed-by: Carlos O'Donell <carlos@redhat.com> > --- > scripts/localplt.awk | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/scripts/localplt.awk b/scripts/localplt.awk > index fe79ca01ab..621ae7d8e8 100644 > --- a/scripts/localplt.awk > +++ b/scripts/localplt.awk > @@ -10,7 +10,8 @@ BEGIN { > } > > FILENAME != lastfile { > - if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) { > + if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0 \ > + && relr_offset == 0) { OK. All of the *_offset variable must be zero to trigger the failure, which would mean we didn't find any of them. Any one of them being non-zero is good enough. > print FILENAME ": *** failed to find expected output (readelf -WSdr)"; > result = 2; > } > @@ -22,6 +23,7 @@ FILENAME != lastfile { > jmprel_offset = 0; > rela_offset = 0; > rel_offset = 0; > + relr_offset = 0; OK. Set relr_offset to zero. > pltrelsz = -1; > delete section_offset_by_address; > } > @@ -77,6 +79,8 @@ in_relocs && relocs_offset == rel_offset && NF >= 5 { > } > } > > +# No need to handle DT_RELR (all packed relocations are relative). OK. > + > in_relocs { next } > > $1 == "Relocation" && $2 == "section" && $5 == "offset" { > @@ -121,4 +125,14 @@ $2 == "(REL)" { > } > next > } > + > +$2 == "(RELR)" { OK. Matches binutils/readelf.c "RELR" output for DT_RELR. > + relr_addr = strtonum($3); > + if (relr_addr in section_offset_by_address) { > + relr_offset = section_offset_by_address[relr_addr]; > + } else { > + print FILENAME ": *** DT_RELR does not match any section's address"; > + result = 2; > + } OK. > +} > END { exit(result) }
Am Freitag, 19. Juli 2024, 22:35:41 MESZ schrieb Carlos O'Donell: > On 7/16/24 6:57 AM, Adhemerval Zanella wrote: > > For each input readelf output, localplt.awk parses each 'Relocation > > section' entry, checks its offset against the dynamic section entry, and > > saves each DT_JMPREL, DT_RELA, and DT_REL offset value it finds. After > > all lines are read, the script checks if any segment offset differed > > from 0, meaning at least one 'Relocation section' was matched. > > > > However, if the shared object was built with RELR support and the static > > linker could place all the relocation on DT_RELR, there would be no > > DT_JMPREL, DT_RELA, and DT_REL entries; only a DT_RELR. > > Agreed, as is the case in ppc64le today. > > > > > For the current three ABIs that support (aarch64, x86, and powerpc64), > > the powerpc64 ld.so shows the behavior above. Both x86_64 and aarch64 > > show extra relocations on '.rela.dyn', which makes the script check to > > succeed. > > > > This patch fixes by handling DT_RELR, where the offset is checked > > against the dynamic section entries and if the shared object contains an > > entry it means that there are no extra PLT entries (since all > > relocations are relative). > > > > It fixes the elf/check-localplt failure on powerpc. > > > > Checked with a build/check for aarch64-linux-gnu, x86_64-linux-gnu, > > i686-linux-gnu, arm-linux-gnueabihf, s390x-linux-gnu, powerpc-linux-gnu, > > powerpc64-linux-gnu, and powerpc64le-linux-gnu. > > LGTM. Nice to add full DT_RELR support for this. > > Reviewed-by: Carlos O'Donell <carlos@redhat.com> > And pushed.
diff --git a/scripts/localplt.awk b/scripts/localplt.awk index fe79ca01ab..621ae7d8e8 100644 --- a/scripts/localplt.awk +++ b/scripts/localplt.awk @@ -10,7 +10,8 @@ BEGIN { } FILENAME != lastfile { - if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) { + if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0 \ + && relr_offset == 0) { print FILENAME ": *** failed to find expected output (readelf -WSdr)"; result = 2; } @@ -22,6 +23,7 @@ FILENAME != lastfile { jmprel_offset = 0; rela_offset = 0; rel_offset = 0; + relr_offset = 0; pltrelsz = -1; delete section_offset_by_address; } @@ -77,6 +79,8 @@ in_relocs && relocs_offset == rel_offset && NF >= 5 { } } +# No need to handle DT_RELR (all packed relocations are relative). + in_relocs { next } $1 == "Relocation" && $2 == "section" && $5 == "offset" { @@ -121,4 +125,14 @@ $2 == "(REL)" { } next } + +$2 == "(RELR)" { + relr_addr = strtonum($3); + if (relr_addr in section_offset_by_address) { + relr_offset = section_offset_by_address[relr_addr]; + } else { + print FILENAME ": *** DT_RELR does not match any section's address"; + result = 2; + } +} END { exit(result) }