* Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
> Add AMD-specific implementation of perf_snapshot_branch_stack static call that
> allows LBR capture from arbitrary points in the kernel. This is utilized by
> BPF programs. See patch #3 for all the details.
>
> Patches #1 and #2 are preparatory steps to ensure LBR freezing is completely
> inlined and have no branches, to minimize LBR snapshot contamination.
>
> Patch #4 removes an artificial restriction on perf events with LBR enabled.
>
> Andrii Nakryiko (4):
> perf/x86/amd: ensure amd_pmu_core_disable_all() is always inlined
> perf/x86/amd: avoid taking branches before disabling LBR
> perf/x86/amd: support capturing LBR from software events
> perf/x86/amd: don't reject non-sampling events with configured LBR
>
> arch/x86/events/amd/core.c | 37 +++++++++++++++++++++++++++++++++++-
> arch/x86/events/amd/lbr.c | 11 +----------
> arch/x86/events/perf_event.h | 11 +++++++++++
> 3 files changed, 48 insertions(+), 11 deletions(-)
So there's a new conflict with patch #2, probably due to interaction
with this recent fix that is now upstream:
598c2fafc06f ("perf/x86/amd/lbr: Use freeze based on availability")
I don't think it should change the logic of the snapshot feature
materially, X86_FEATURE_AMD_LBR_PMC_FREEZE should be orthogonal to it,
as the LBR snapshot isn't taken from a PMI.
Thanks,
Ingo
