From: Nathan Chancellor <nathan@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: "Fāng-ruì Sòng" <maskray@google.com>,
"Josh Poimboeuf" <jpoimboe@redhat.com>,
lma@semihalf.com, "Guenter Roeck" <groeck@google.com>,
"Juergen Gross" <jgross@suse.com>,
lb@semihalf.com, LKML <linux-kernel@vger.kernel.org>,
mbenes@suse.com, "Radosław Biernacki" <rad@semihalf.com>,
upstream@semihalf.com,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Sami Tolvanen" <samitolvanen@google.com>
Subject: Re: [PATCH v3 16/16] objtool,x86: Rewrite retpoline thunk calls
Date: Tue, 8 Jun 2021 09:58:03 -0700 [thread overview]
Message-ID: <e351ac97-4038-61b5-b373-63698a787fc1@kernel.org> (raw)
In-Reply-To: <CAKwvOdkuJBwZRigeqdZGevPF9WHyrC5pBAsz6_tWdXAc-wO+1A@mail.gmail.com>
On 6/7/2021 1:54 PM, 'Nick Desaulniers' via Clang Built Linux wrote:
> On Mon, Jun 7, 2021 at 2:46 AM Peter Zijlstra <peterz@infradead.org> wrote:
>>
>
> Thanks, the below diff resolves the linker error reported in
> https://github.com/ClangBuiltLinux/linux/issues/1388
>
> Both readelf implementations seem happy with the results, too.
>
> Tested-by: Nick Desaulniers <ndesaulniers@google.com>
>
> Nathan,
> Can you please test the below diff and see if that resolves your boot
> issue reported in:
> https://github.com/ClangBuiltLinux/linux/issues/1384
Unfortunately, it does not appear to resolve that issue.
$ git log -2 --decorate=no --oneline
eea6a9d6d277 Peter's fix
614124bea77e Linux 5.13-rc5
$ strings /mnt/c/Users/natec/Linux/kernel-investigation | grep microsoft
5.13.0-rc5-microsoft-standard-WSL2-00001-geea6a9d6d277
(nathan@archlinux-ax161) #3 SMP Tue Jun 8 09:46:19 MST 2021
My VM still never makes it to userspace.
>> ---
>> tools/objtool/elf.c | 25 ++++++++++++++++++++++++-
>> 1 file changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
>> index 743c2e9d0f56..41bca1d13d8e 100644
>> --- a/tools/objtool/elf.c
>> +++ b/tools/objtool/elf.c
>> @@ -717,7 +717,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
>>
>> struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
>> {
>> - struct section *symtab;
>> + struct section *symtab, *symtab_shndx;
>> struct symbol *sym;
>> Elf_Data *data;
>> Elf_Scn *s;
>> @@ -769,6 +769,29 @@ struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name)
>> symtab->len += data->d_size;
>> symtab->changed = true;
>>
>> + symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
>> + if (symtab_shndx) {
>> + s = elf_getscn(elf->elf, symtab_shndx->idx);
>> + if (!s) {
>> + WARN_ELF("elf_getscn");
>> + return NULL;
>> + }
>> +
>> + data = elf_newdata(s);
>> + if (!data) {
>> + WARN_ELF("elf_newdata");
>> + return NULL;
>> + }
>> +
>> + data->d_buf = &sym->sym.st_size; /* conveniently 0 */
>> + data->d_size = sizeof(Elf32_Word);
>> + data->d_align = 4;
>> + data->d_type = ELF_T_WORD;
>> +
>> + symtab_shndx->len += 4;
>> + symtab_shndx->changed = true;
>> + }
>> +
>> sym->sec = find_section_by_index(elf, 0);
>>
>> elf_add_symbol(elf, sym);
>
>
> The only thing that's still different is that the `file` command still
> prints "no section header."
>
> $ find . -name \*.lto.o | xargs file | rev | cut -d , -f 1 | rev |
> sort | uniq -c
> 1 no section header
> 8377 not stripped
> 1 too many section headers (33683)
> 1 too many section headers (50758)
> $ file --version
> file-5.39
>
> That's drivers/gpu/drm/amd/amdgpu/amdgpu.lto.o, fs/xfs/xfs.lto.o,
> drivers/gpu/drm/i915/i915.lto.o, respectively. I'm not sure that's a
> problem, yet, and whether 9bc0bb50727c8ac69fbb33fb937431cf3518ff37 is
> even related yet; those might just be huge drivers and figured it was
> reporting somewhere in case it ever comes up again. CONFIG_LTO
> implies -ffunction-sections -fdata-sections, and
> CONFIG_LD_DEAD_CODE_DATA_ELIMINATION explicitly sets those, too.
>
next prev parent reply other threads:[~2021-06-08 16:58 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 15:11 [PATCH v3 00/16] x86,objtool: Optimize !RETPOLINE Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 01/16] x86: Add insn_decode_kernel() Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 02/16] x86/alternatives: Optimize optimize_nops() Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:11 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 03/16] x86/retpoline: Simplify retpolines Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-04-06 8:56 ` David Laight
2021-03-26 15:12 ` [PATCH v3 04/16] objtool: Correctly handle retpoline thunk calls Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 05/16] objtool: Per arch retpoline naming Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] objtool: Handle per " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 06/16] objtool: Fix static_call list generation Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 07/16] objtool: Rework rebuild_reloc logic Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` [tip: x86/core] objtool: Rework the elf_rebuild_reloc_section() logic tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 08/16] objtool: Add elf_create_reloc() helper Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 09/16] objtool: Implicitly create reloc sections Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` [tip: x86/core] objtool: Create reloc sections implicitly tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 10/16] objtool: Extract elf_strtab_concat() Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 11/16] objtool: Extract elf_symbol_add() Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 12/16] objtool: Add elf_create_undef_symbol() Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 13/16] objtool: Keep track of retpoline call sites Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 14/16] objtool: Cache instruction relocs Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 15/16] objtool: Skip magical retpoline .altinstr_replacement Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-26 15:12 ` [PATCH v3 16/16] objtool,x86: Rewrite retpoline thunk calls Peter Zijlstra
2021-03-29 16:38 ` Josh Poimboeuf
2021-06-02 15:51 ` Lukasz Majczak
2021-06-02 16:56 ` Peter Zijlstra
2021-06-02 17:10 ` Peter Zijlstra
2021-06-02 20:43 ` Josh Poimboeuf
2021-06-04 20:50 ` Nick Desaulniers
2021-06-04 23:27 ` Nick Desaulniers
2021-06-04 23:50 ` Fangrui Song
2021-06-05 10:38 ` Peter Zijlstra
2021-06-06 1:58 ` Fāng-ruì Sòng
2021-06-07 7:56 ` Peter Zijlstra
2021-06-07 9:22 ` Peter Zijlstra
2021-06-07 9:45 ` Peter Zijlstra
2021-06-07 17:23 ` Fāng-ruì Sòng
2021-06-07 18:25 ` Peter Zijlstra
2021-06-07 20:54 ` Nick Desaulniers
2021-06-08 9:56 ` Peter Zijlstra
2021-06-08 16:58 ` Nathan Chancellor [this message]
2021-06-08 17:22 ` Peter Zijlstra
2021-06-08 17:29 ` Nathan Chancellor
2021-06-08 18:17 ` Peter Zijlstra
2021-06-08 18:49 ` Nathan Chancellor
2021-06-09 7:11 ` Lukasz Majczak
2021-06-09 7:20 ` Peter Zijlstra
2021-06-09 12:23 ` Lukasz Majczak
2021-06-09 15:08 ` Peter Zijlstra
2021-06-09 15:11 ` Peter Zijlstra
2021-06-09 15:56 ` Nathan Chancellor
2021-06-08 18:18 ` Nick Desaulniers
2021-06-07 18:19 ` Peter Zijlstra
2021-06-07 18:27 ` Fāng-ruì Sòng
2021-06-07 18:47 ` Peter Zijlstra
2021-04-01 15:08 ` [tip: x86/core] objtool/x86: " tip-bot2 for Peter Zijlstra
2021-04-03 11:10 ` tip-bot2 for Peter Zijlstra
2021-03-30 15:02 ` [PATCH v3 00/16] x86,objtool: Optimize !RETPOLINE Miroslav Benes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e351ac97-4038-61b5-b373-63698a787fc1@kernel.org \
--to=nathan@kernel.org \
--cc=clang-built-linux@googlegroups.com \
--cc=groeck@google.com \
--cc=jgross@suse.com \
--cc=jpoimboe@redhat.com \
--cc=lb@semihalf.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lma@semihalf.com \
--cc=maskray@google.com \
--cc=mbenes@suse.com \
--cc=ndesaulniers@google.com \
--cc=peterz@infradead.org \
--cc=rad@semihalf.com \
--cc=samitolvanen@google.com \
--cc=upstream@semihalf.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).