diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2021-07-20 17:15:04 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-08-04 03:53:39 +0300 |
| commit | cf9c615cde49fb5d2480549c8c955a0a387798d3 (patch) | |
| tree | 896c680a6fad98416d7ba3e0f291d4dac96e6e21 /arch/powerpc/perf | |
| parent | e9ef81e1079b0c4c374fba0f9affa7129c7c913b (diff) | |
| download | linux-cf9c615cde49fb5d2480549c8c955a0a387798d3.tar.xz | |
powerpc/64s/perf: Always use SIAR for kernel interrupts
If an interrupt is taken in kernel mode, always use SIAR for it rather than
looking at regs_sipr. This prevents samples piling up around interrupt
enable (hard enable or interrupt replay via soft enable) in PMUs / modes
where the PR sample indication is not in synch with SIAR.
This results in better sampling of interrupt entry and exit in particular.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210720141504.420110-1-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/perf')
| -rw-r--r-- | arch/powerpc/perf/core-book3s.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index bb0ee716de91..91203ed9d0ff 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -340,6 +340,13 @@ static inline void perf_read_regs(struct pt_regs *regs) * If the PMU doesn't update the SIAR for non marked events use * pt_regs. * + * If regs is a kernel interrupt, always use SIAR. Some PMUs have an + * issue with regs_sipr not being in synch with SIAR in interrupt entry + * and return sequences, which can result in regs_sipr being true for + * kernel interrupts and SIAR, which has the effect of causing samples + * to pile up at mtmsrd MSR[EE] 0->1 or pending irq replay around + * interrupt entry/exit. + * * If the PMU has HV/PR flags then check to see if they * place the exception in userspace. If so, use pt_regs. In * continuous sampling mode the SIAR and the PMU exception are @@ -356,6 +363,8 @@ static inline void perf_read_regs(struct pt_regs *regs) use_siar = 1; else if ((ppmu->flags & PPMU_NO_CONT_SAMPLING)) use_siar = 0; + else if (!user_mode(regs)) + use_siar = 1; else if (!(ppmu->flags & PPMU_NO_SIPR) && regs_sipr(regs)) use_siar = 0; else |