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perf auxtrace arm: Support compat_auxtrace_mmap__{read_head|write_tail}

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When the tool runs with compat mode on Arm platform, the kernel is in
64-bit mode and user space is in 32-bit mode; the user space can use
instructions "ldrd" and "strd" for 64-bit value atomicity.

This patch adds compat_auxtrace_mmap__{read_head|write_tail} for arm
building, it uses "ldrd" and "strd" instructions to ensure accessing
atomicity for aux head and tail.  The file arch/arm/util/auxtrace.c is
built for arm and arm64 building, these two functions are not needed for
arm64, so check the compiler macro "__arm__" to only include them for
arm building.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: James Clark <james.clark@arm.com>
Tested-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Russell King (oracle)" <linux@armlinux.org.uk>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20210829102238.19693-3-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Leo Yan 2021-08-29 18:22:38 +08:00 committed by Arnaldo Carvalho de Melo
parent bbc49f1202
commit 474b3f2882
1 changed files with 32 additions and 0 deletions
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32
tools/perf/arch/arm/util/auxtrace.c
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@ -107,3 +107,35 @@ struct auxtrace_record
*err = 0;
return NULL;
}
#if defined(__arm__)
u64 compat_auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
{
struct perf_event_mmap_page *pc = mm->userpg;
u64 result;
__asm__ __volatile__(
" ldrd %0, %H0, [%1]"
: "=&r" (result)
: "r" (&pc->aux_head), "Qo" (pc->aux_head)
);
return result;
}
int compat_auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
{
struct perf_event_mmap_page *pc = mm->userpg;
/* Ensure all reads are done before we write the tail out */
smp_mb();
__asm__ __volatile__(
" strd %2, %H2, [%1]"
: "=Qo" (pc->aux_tail)
: "r" (&pc->aux_tail), "r" (tail)
);
return 0;
}
#endif