Namhyung Kim eba1f853ed 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>
2024-05-02 10:54:31 -03:00
2024-04-21 12:35:54 -07:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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