perf/x86/intel: Fix large period handling on Broadwell CPUs

Large fixed period values could be truncated on Broadwell, for example:

  perf record -e cycles -c 10000000000

Here the fixed period is 0x2540BE400, but the period which finally applied is
0x540BE400 - which is wrong.

The reason is that x86_pmu::limit_period() uses an u32 parameter, so the
high 32 bits of 'period' get truncated.

This bug was introduced in:

  commit 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds")

It's safe to use u64 instead of u32:

 - Although the 'left' is s64, the value of 'left' must be positive when
   calling limit_period().

 - bdw_limit_period() only modifies the lowest 6 bits, it doesn't touch
   the higher 32 bits.

Signed-off-by: Kan Liang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Fixes: 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds")
Link: http://lkml.kernel.org/r/[email protected]
[ Rewrote unacceptably bad changelog. ]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions