commit fdbef8c4e68ad423416aa6cc93d1616d6f8ac5b3 upstream.

Commit 3a95200d ("arm_pmu: Change API to support 64bit counter values")
changes the input "value" type from 32-bit to 64-bit, which introduces the
following problem: ARMv7 PMU counters is 32-bit width, in big-endian mode,
write counter uses high 32-bit, which writes an incorrect value.

Before:

 Performance counter stats for 'ls':

              2.22 msec task-clock                #    0.675 CPUs utilized
                 0      context-switches          #    0.000 K/sec
                 0      cpu-migrations            #    0.000 K/sec
                49      page-faults               #    0.022 M/sec
        2150476593      cycles                    #  966.663 GHz
        2148588788      instructions              #    1.00  insn per cycle
        2147745484      branches                  # 965435.074 M/sec
        2147508540      branch-misses             #   99.99% of all branches

None of the above hw event counters are correct.

Solution:

"value" forcibly converted to 32-bit type before being written to PMU register.

After:

 Performance counter stats for 'ls':

              2.09 msec task-clock                #    0.681 CPUs utilized
                 0      context-switches          #    0.000 K/sec
                 0      cpu-migrations            #    0.000 K/sec
                46      page-faults               #    0.022 M/sec
           2807301      cycles                    #    1.344 GHz
           1060159      instructions              #    0.38  insn per cycle
            250496      branches                  #  119.914 M/sec
             23192      branch-misses             #    9.26% of all branches

Fixes: 3a95200d

 ("arm_pmu: Change API to support 64bit counter values")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210430012659.232110-1-yangjihong1@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>