| Message ID | cd0f6bdfdf1ee096fb2c07e7b38940921b8e9118.1637764848.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | recordmcount: Support empty section from recent binutils | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
Le 24/11/2021 à 15:43, Christophe Leroy a écrit : > Looks like recent binutils (2.36 and over ?) may empty some section, > leading to failure like: > > Cannot find symbol for section 11: .text.unlikely. > kernel/kexec_file.o: failed > make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 > > In order to avoid that, ensure that the section has a content before > returning it's name in has_rel_mcount(). This patch doesn't work, on PPC32 I get the following message with this patch applied: [ 0.000000] ftrace: No functions to be traced? Without the patch I get: [ 0.000000] ftrace: allocating 22381 entries in 66 pages [ 0.000000] ftrace: allocated 66 pages with 2 groups Christophe > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > Link: https://github.com/linuxppc/issues/issues/388 > Link: https://lore.kernel.org/all/20210215162209.5e2a475b@gandalf.local.home/ > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > scripts/recordmcount.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h > index 1e9baa5c4fc6..cc6600b729ae 100644 > --- a/scripts/recordmcount.h > +++ b/scripts/recordmcount.h > @@ -575,6 +575,8 @@ static char const *has_rel_mcount(Elf_Shdr const *const relhdr, > char const *const shstrtab, > char const *const fname) > { > + if (!shdr0->sh_size) > + return NULL; > if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA) > return NULL; > return __has_rel_mcount(relhdr, shdr0, shstrtab, fname); >
On Fri, 26 Nov 2021 08:43:23 +0000 LEROY Christophe <christophe.leroy@csgroup.eu> wrote: > Le 24/11/2021 à 15:43, Christophe Leroy a écrit : > > Looks like recent binutils (2.36 and over ?) may empty some section, > > leading to failure like: > > > > Cannot find symbol for section 11: .text.unlikely. > > kernel/kexec_file.o: failed > > make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 > > > > In order to avoid that, ensure that the section has a content before > > returning it's name in has_rel_mcount(). > > This patch doesn't work, on PPC32 I get the following message with this > patch applied: > > [ 0.000000] ftrace: No functions to be traced? > > Without the patch I get: > > [ 0.000000] ftrace: allocating 22381 entries in 66 pages > [ 0.000000] ftrace: allocated 66 pages with 2 groups Because of this report, I have not applied this patch (even though I was about to push it to Linus). I'm pulling it from my queue until this gets resolved. Thanks, -- Steve
Le 29/11/2021 à 18:43, Steven Rostedt a écrit : > On Fri, 26 Nov 2021 08:43:23 +0000 > LEROY Christophe <christophe.leroy@csgroup.eu> wrote: > >> Le 24/11/2021 à 15:43, Christophe Leroy a écrit : >>> Looks like recent binutils (2.36 and over ?) may empty some section, >>> leading to failure like: >>> >>> Cannot find symbol for section 11: .text.unlikely. >>> kernel/kexec_file.o: failed >>> make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 >>> >>> In order to avoid that, ensure that the section has a content before >>> returning it's name in has_rel_mcount(). >> >> This patch doesn't work, on PPC32 I get the following message with this >> patch applied: >> >> [ 0.000000] ftrace: No functions to be traced? >> >> Without the patch I get: >> >> [ 0.000000] ftrace: allocating 22381 entries in 66 pages >> [ 0.000000] ftrace: allocated 66 pages with 2 groups > > Because of this report, I have not applied this patch (even though I was > about to push it to Linus). > > I'm pulling it from my queue until this gets resolved. > I have no idea on how to fix that for the moment. With GCC 10 (binutils 2.36) an objdump -x on kernel/kexec_file.o gives: 0000000000000000 l d .text.unlikely 0000000000000000 .text.unlikely 0000000000000000 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations_add 0000000000000038 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations With GCC 11 (binutils 2.37) the same gives: 0000000000000000 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations_add 0000000000000038 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations The problem is that recordmcount drops weak symbols, and it doesn't find any non-weak symbol in .text.unlikely Explication given at https://elixir.bootlin.com/linux/v5.16-rc2/source/scripts/recordmcount.h#L506 I have no idea on what to do. Thanks Christophe
On Mon, 29 Nov 2021 at 22:43, Christophe Leroy <christophe.leroy@csgroup.eu> wrote: > > > > Le 29/11/2021 à 18:43, Steven Rostedt a écrit : > > On Fri, 26 Nov 2021 08:43:23 +0000 > > LEROY Christophe <christophe.leroy@csgroup.eu> wrote: > > > >> Le 24/11/2021 à 15:43, Christophe Leroy a écrit : > >>> Looks like recent binutils (2.36 and over ?) may empty some section, > >>> leading to failure like: > >>> > >>> Cannot find symbol for section 11: .text.unlikely. > >>> kernel/kexec_file.o: failed > >>> make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 > >>> > >>> In order to avoid that, ensure that the section has a content before > >>> returning it's name in has_rel_mcount(). > >> > >> This patch doesn't work, on PPC32 I get the following message with this > >> patch applied: > >> > >> [ 0.000000] ftrace: No functions to be traced? > >> > >> Without the patch I get: > >> > >> [ 0.000000] ftrace: allocating 22381 entries in 66 pages > >> [ 0.000000] ftrace: allocated 66 pages with 2 groups > > > > Because of this report, I have not applied this patch (even though I was > > about to push it to Linus). > > > > I'm pulling it from my queue until this gets resolved. > > > > I have no idea on how to fix that for the moment. > > With GCC 10 (binutils 2.36) an objdump -x on kernel/kexec_file.o gives: > > 0000000000000000 l d .text.unlikely 0000000000000000 .text.unlikely > 0000000000000000 w F .text.unlikely 0000000000000038 > .arch_kexec_apply_relocations_add > 0000000000000038 w F .text.unlikely 0000000000000038 > .arch_kexec_apply_relocations > > > With GCC 11 (binutils 2.37) the same gives: > > 0000000000000000 w F .text.unlikely 0000000000000038 > .arch_kexec_apply_relocations_add > 0000000000000038 w F .text.unlikely 0000000000000038 > .arch_kexec_apply_relocations > > > The problem is that recordmcount drops weak symbols, and it doesn't find > any non-weak symbol in .text.unlikely > > Explication given at > https://elixir.bootlin.com/linux/v5.16-rc2/source/scripts/recordmcount.h#L506 > > I have no idea on what to do. Did you end up finding a solution for this issue? Cheers, Joel
Le 29/03/2022 à 00:31, Joel Stanley a écrit : > On Mon, 29 Nov 2021 at 22:43, Christophe Leroy > <christophe.leroy@csgroup.eu> wrote: >> >> >> >> Le 29/11/2021 à 18:43, Steven Rostedt a écrit : >>> On Fri, 26 Nov 2021 08:43:23 +0000 >>> LEROY Christophe <christophe.leroy@csgroup.eu> wrote: >>> >>>> Le 24/11/2021 à 15:43, Christophe Leroy a écrit : >>>>> Looks like recent binutils (2.36 and over ?) may empty some section, >>>>> leading to failure like: >>>>> >>>>> Cannot find symbol for section 11: .text.unlikely. >>>>> kernel/kexec_file.o: failed >>>>> make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 >>>>> >>>>> In order to avoid that, ensure that the section has a content before >>>>> returning it's name in has_rel_mcount(). >>>> >>>> This patch doesn't work, on PPC32 I get the following message with this >>>> patch applied: >>>> >>>> [ 0.000000] ftrace: No functions to be traced? >>>> >>>> Without the patch I get: >>>> >>>> [ 0.000000] ftrace: allocating 22381 entries in 66 pages >>>> [ 0.000000] ftrace: allocated 66 pages with 2 groups >>> >>> Because of this report, I have not applied this patch (even though I was >>> about to push it to Linus). >>> >>> I'm pulling it from my queue until this gets resolved. >>> >> >> I have no idea on how to fix that for the moment. >> >> With GCC 10 (binutils 2.36) an objdump -x on kernel/kexec_file.o gives: >> >> 0000000000000000 l d .text.unlikely 0000000000000000 .text.unlikely >> 0000000000000000 w F .text.unlikely 0000000000000038 >> .arch_kexec_apply_relocations_add >> 0000000000000038 w F .text.unlikely 0000000000000038 >> .arch_kexec_apply_relocations >> >> >> With GCC 11 (binutils 2.37) the same gives: >> >> 0000000000000000 w F .text.unlikely 0000000000000038 >> .arch_kexec_apply_relocations_add >> 0000000000000038 w F .text.unlikely 0000000000000038 >> .arch_kexec_apply_relocations >> >> >> The problem is that recordmcount drops weak symbols, and it doesn't find >> any non-weak symbol in .text.unlikely >> >> Explication given at >> https://elixir.bootlin.com/linux/v5.16-rc2/source/scripts/recordmcount.h#L506 >> >> I have no idea on what to do. > > Did you end up finding a solution for this issue? > Not really, my solution was to switch to the kernel compiler at https://mirrors.edge.kernel.org/pub/tools/crosstool/ which embeds binutils 2.36 But it looks like using objtool instead of recordmcount doesn't exhibit the problem. https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220318105140.43914-4-sv@linux.ibm.com/ Christophe
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h index 1e9baa5c4fc6..cc6600b729ae 100644 --- a/scripts/recordmcount.h +++ b/scripts/recordmcount.h @@ -575,6 +575,8 @@ static char const *has_rel_mcount(Elf_Shdr const *const relhdr, char const *const shstrtab, char const *const fname) { + if (!shdr0->sh_size) + return NULL; if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA) return NULL; return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
Looks like recent binutils (2.36 and over ?) may empty some section, leading to failure like: Cannot find symbol for section 11: .text.unlikely. kernel/kexec_file.o: failed make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 In order to avoid that, ensure that the section has a content before returning it's name in has_rel_mcount(). Suggested-by: Steven Rostedt <rostedt@goodmis.org> Link: https://github.com/linuxppc/issues/issues/388 Link: https://lore.kernel.org/all/20210215162209.5e2a475b@gandalf.local.home/ Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- scripts/recordmcount.h | 2 ++ 1 file changed, 2 insertions(+)