Re: [PATCH] perf symbol: Look for ImageBase in PE file to compute .text offset
From: Arnaldo Carvalho de Melo <acme@kernel.org>
Date: 2021-09-09 20:28:04
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Em Thu, Sep 09, 2021 at 09:26:36PM +0200, Remi Bernon escreveu:
Instead of using the file offset in the debug file. This fixes a regression from 00a3423492bc90be99e529a64f13fdd80a0e8c0a, causing incorrect symbol resolution when debug file have been stripped from non-debug sections (in which case its .text section is empty and doesn't have any file position). The debug files could also be created with a different file alignment, and have different file positions from the mmap-ed binary, or have the section reordered. This instead looks for the file image base, using the corresponding bfd *ABS* symbols. As PE symbols only have 4 bytes, it also needs to keep .text section vma high bits.
I added a:
Fixes: 00a3423492bc90be ("perf symbols: Make dso__load_bfd_symbols() load PE files from debug cache only")
To help stable@kernel.org to pick it, its on my local tree now.
It would be great to get a:
Reviewed-by: Nicholas Fraser <redacted>
Can we have it, please?
- Arnaldo
quoted hunk ↗ jump to hunk
Signed-off-by: Remi Bernon <redacted> --- Hi! As I'm not updating it often I only recently realized that perf had a regression when using stripped debug info files, and all symbols from PE files are off. This should make things better. Cheers, tools/perf/util/symbol.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 77fc46ca07c0..0fc9a5410739 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c@@ -1581,10 +1581,6 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile) if (bfd_get_flavour(abfd) == bfd_target_elf_flavour) goto out_close; - section = bfd_get_section_by_name(abfd, ".text"); - if (section) - dso->text_offset = section->vma - section->filepos; - symbols_size = bfd_get_symtab_upper_bound(abfd); if (symbols_size == 0) { bfd_close(abfd);@@ -1602,6 +1598,22 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile) if (symbols_count < 0) goto out_free; + section = bfd_get_section_by_name(abfd, ".text"); + if (section) { + for (i = 0; i < symbols_count; ++i) { + if (!strcmp(bfd_asymbol_name(symbols[i]), "__ImageBase") || + !strcmp(bfd_asymbol_name(symbols[i]), "__image_base__")) + break; + } + if (i < symbols_count) { + /* PE symbols can only have 4 bytes, so use .text high bits */ + dso->text_offset = section->vma - (u32)section->vma; + dso->text_offset += (u32)bfd_asymbol_value(symbols[i]); + } else { + dso->text_offset = section->vma - section->filepos; + } + } + qsort(symbols, symbols_count, sizeof(asymbol *), bfd_symbols__cmpvalue); #ifdef bfd_get_section-- 2.33.0
-- - Arnaldo