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From: Peter Zijlstra <peterz@infradead.org>
To: Fangrui Song <maskray@google.com>
Cc: Nick Desaulniers <ndesaulniers@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, 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>,
	Nathan Chancellor <nathan@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>
Subject: Re: [PATCH v3 16/16] objtool,x86: Rewrite retpoline thunk calls
Date: Sat, 5 Jun 2021 12:38:51 +0200	[thread overview]
Message-ID: <YLtUO/thYUp2wU7k@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210604235046.w3hazgcpsg4oefex@google.com>

On Fri, Jun 04, 2021 at 04:50:46PM -0700, Fangrui Song wrote:
> On 2021-06-04, 'Nick Desaulniers' via Clang Built Linux wrote:

> > is producing the linker error:
> > 
> > ld.lld: error: drivers/gpu/drm/amd/amdgpu/amdgpu.lto.o:
> > SHT_SYMTAB_SHNDX has 79581 entries, but the symbol table associated
> > has 79582
> > 
> > Readelf having issues with the output:
> > $ readelf -s amdgpu.lto.o.orig
> > <works fine>
> > $ readelf -s amdgpu.lto.o
> > readelf: Error: Reading 73014451695 bytes extends past end of file for
> > string table
> > $ llvm-readelf -s amdgpu.lto.o
> > llvm-readelf: error: 'amdgpu.lto.o': unable to continue dumping, the
> > file is corrupt: section table goes past the end of file
> > 

> tools/objtool/elf.c:elf_add_symbol may not update .symtab_shndx .
> Speaking of llvm-objcopy, it finalizes the content of .symtab_shndx when .symtab
> is finalized. objtool may want to adopt a similar approach.
> 
> read_symbols searches for the section ".symtab_shndx". It'd be better to
> use the section type SHT_SYMTAB_SHNDX.

I think you've absolutely nailed it; but would you have more information
or a code reference to what you're speaking about? My complete ELF
and libelf knowledge is very limited and as demonstrated here, I'm not
at all sure how all that extended index stuff is supposed to work.

  reply	other threads:[~2021-06-05 10:39 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 [this message]
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
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

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