perf symbols: skip livepatch symbols when loading kallsyms

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Livepatch modules contain special symbols (prefixed by ".klp.sym.") that
act as relocation placeholders.  Once resolved, they point to the same
addresses as the original kernel symbols they reference. [1]

These special symbols confuse the 'vmlinux symtab matches kallsyms' perf
test as kallsyms may report multiple symbols sharing a single kernel
address.  For example:

  kallsyms (without livepatch)
  ----------------------------
  ffffffff81a41110 T __pfx_arch_release_task_struct
> ffffffff81a41120 T arch_release_task_struct
  ffffffff81a41140 T __pfx_exit_thread
  ffffffff81a41150 T exit_thread

  kallsyms (with livepatch loaded)
  ---------------------------------
  ffffffff81a41110 T __pfx_arch_release_task_struct
> ffffffff81a41120 T arch_release_task_struct
  ffffffff81a41140 T __pfx_exit_thread
  ffffffff81a41150 T exit_thread
> ffffffff81a41120 w .klp.sym.vmlinux.arch_release_task_struct,0  [kpatch_5_14_0_570_94_1_1_3]

When perf loads kallsyms, both symbols are inserted into the symbol
table at the same address, corrupting symbol end-address calculations
and causing test failures.

Filter out symbols prefixed with ".klp.sym." when loading kallsyms, as
they alias existing kernel symbols.

Link: https://docs.kernel.org/livepatch/module-elf-format.html#livepatch-symbols [1]
Reported-and-tested-by:
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

...

This commit is contained in:

Joe Lawrence 2026-06-26 17:21:39 -04:00 • committed by Namhyung Kim

parent e1065ed188

commit 5a9dd83589

2 changed files with 14 additions and 2 deletions

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4

tools/perf/util/symbol.c

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12

tools/perf/util/symbol.h

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