Re: [PATCH 2/3] perf symbol-elf: Fix zero-size symbol end calculation across .symtab and .dynsym

[sashiko-bot@kernel.org]

> When loading symbols from an ELF binary in dso__load_sym(),
> dso__load_sym_internal() can be invoked multiple times: first for
> .symtab (or .gnu_debugdata's .symtab) and then for .dynsym.
> 
> Previously, dso__load_sym_internal() ran symbols__fixup_end() and
> symbols__fixup_duplicate() at the end of each individual symbol table
> load. Consequently, a zero-size symbol in .symtab had its end address
> extended to the start of the next .symtab symbol before .dynsym was
> loaded. If an exported function existed only in .dynsym (for example,
> when stripped from .symtab or when using .gnu_debugdata minidebuginfo)
> at an address between the two .symtab symbols, the zero-size .symtab
> symbol overlapped the .dynsym function and samples inside the .dynsym
> function were misattributed to the preceding zero-size symbol.
> 
> Move symbols__fixup_end(), symbols__fixup_duplicate(), and
> maps__fixup_end() from dso__load_sym_internal() to dso__load_sym() so
> they run once after all symbol tables have been loaded into the DSO, and
> add a unit test in 'perf test symbols' verifying that a zero-size
> .symtab symbol ends at a following .dynsym-only function rather than
> overlapping it.
> 
> Fixes: 87704345cc60 ("perf symbol-elf: Decode dynsym even if symtab exists")
> Fixes: b10f74308e13 ("perf symbol: Support .gnu_debugdata for symbols")
> Suggested-by: Alireza Haghdoost <haghdoost@uber.com>
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261031063549.1281324-1-irogers@google.com?part=2