perf annotate-data: Check memory access with two registers
authorNamhyung Kim <namhyung@kernel.org>
Thu, 2 May 2024 06:00:09 +0000 (23:00 -0700)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Thu, 2 May 2024 13:54:31 +0000 (10:54 -0300)
commiteba1f853edf794ec259ec7b5e5a6efee5ede989f
tree7d50b2c63ae52c7326ec9c580e374045c71565a1
parent4449c9047dc6f9f68333a720958cd7b58225910d
perf annotate-data: Check memory access with two registers

The following instruction pattern is used to access a global variable.

  mov     $0x231c0, %rax
  movsql  %edi, %rcx
  mov     -0x7dc94ae0(,%rcx,8), %rcx
  cmpl    $0x0, 0xa60(%rcx,%rax,1)     <<<--- here

The first instruction set the address of the per-cpu variable (here, it
is 'runqueues' of type 'struct rq').  The second instruction seems like
a cpu number of the per-cpu base.  The third instruction get the base
offset of per-cpu area for that cpu.  The last instruction compares the
value of the per-cpu variable at the offset of 0xa60.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240502060011.1838090-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/util/annotate-data.c