Re: [PATCH v3 1/3] perf: use hweight64 instead of hweight_long

Arnaldo Carvalho de Melo
2019-04-10T13:08:47Z

Em Wed, Apr 10, 2019 at 04:16:43PM +0800, Mao Han escreveu:
> On 32-bits platform with more than 32 registers, the 64 bits mask is
> truncate to the lower 32 bits and the return value of hweight_long will
> always smaller than 32. When kernel outputs more than 32 registers, but
> the user perf program only counts 32, there will be a data mismatch
> result to overflow check fail.
>
> CC: Peter Zijlstra <peterz@infradead.org>
> CC: Ingo Molnar <mingo@redhat.com>
> CC: Arnaldo Carvalho de Melo <acme@kernel.org>
> CC: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> CC: Jiri Olsa <jolsa@redhat.com>
> CC: Namhyung Kim <namhyung@kernel.org>
>
> Signed-off-by: Mao Han <han_mao@c-sky.com>
> ---
> tools/perf/util/evsel.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 7835e05..73c78be 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -2322,7 +2322,7 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel, union perf_event *event,
> if (data->user_regs.abi) {
> u64 mask = evsel->attr.sample_regs_user;
>
> - sz = hweight_long(mask) * sizeof(u64);
> + sz = hweight64(mask) * sizeof(u64);
> OVERFLOW_CHECK(array, sz, max_size);
> data->user_regs.mask = mask;
> data->user_regs.regs = (u64 *)array;

Later on, in the same function, perf_evsel__parse_sample() we have:

data->intr_regs.abi = PERF_SAMPLE_REGS_ABI_NONE;
if (type & PERF_SAMPLE_REGS_INTR) {
OVERFLOW_CHECK_u64(array);
data->intr_regs.abi = *array;
array++;

if (data->intr_regs.abi != PERF_SAMPLE_REGS_ABI_NONE) {
u64 mask = evsel->attr.sample_regs_intr;

sz = hweight_long(mask) * sizeof(u64);
OVERFLOW_CHECK(array, sz, max_size);
data->intr_regs.mask = mask;
data->intr_regs.regs = (u64 *)array;
array = (void *)array + sz;
}
}

You forgot to convert that one, doing it for you,

Thanks,

- Arnaldo