Adrian Hunter ab66fdace8 perf build-id: Fix caching files with a wrong build ID
Build ID events associate a file name with a build ID.  However, when
using perf inject, there is no guarantee that the file on the current
machine at the current time has that build ID. Fix by comparing the
build IDs and skip adding to the cache if they are different.

Example:

  $ echo "int main() {return 0;}" > prog.c
  $ gcc -o prog prog.c
  $ perf record --buildid-all ./prog
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.019 MB perf.data ]
  $ file-buildid() { file $1 | awk -F= '{print $2}' | awk -F, '{print $1}' ; }
  $ file-buildid prog
  444ad9be165d8058a48ce2ffb4e9f55854a3293e
  $ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf
  444ad9be165d8058a48ce2ffb4e9f55854a3293e
  $ echo "int main() {return 1;}" > prog.c
  $ gcc -o prog prog.c
  $ file-buildid prog
  885524d5aaa24008a3e2b06caa3ea95d013c0fc5

Before:

  $ perf buildid-cache --purge $(pwd)/prog
  $ perf inject -i perf.data -o junk
  $ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf
  885524d5aaa24008a3e2b06caa3ea95d013c0fc5
  $

After:

  $ perf buildid-cache --purge $(pwd)/prog
  $ perf inject -i perf.data -o junk
  $ file-buildid ~/.debug/$(pwd)/prog/444ad9be165d8058a48ce2ffb4e9f55854a3293e/elf

  $

Fixes: 454c407ec17a0c63 ("perf: add perf-inject builtin")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Link: https://lore.kernel.org/r/20220621125144.5623-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-06-26 12:32:55 -03:00
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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 Restructured Text 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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