On Wed, May 27, 2026 at 05:11:59AM -0700, Puranjay Mohan wrote: > Enable bpf_get_branch_snapshot() on ARM64 by implementing the > perf_snapshot_branch_stack static call for BRBE. > > BRBE is paused before masking exceptions to avoid branch buffer > pollution from trace_hardirqs_off(). Exceptions are then masked with > local_daif_save() to prevent PMU overflow pseudo-NMIs from interfering. > If an overflow between pause and DAIF save re-enables BRBE, the snapshot > detects this via BRBFCR_EL1.PAUSED and bails out. > > Branch records are read using perf_entry_from_brbe_regset() with a NULL > event pointer to bypass event-specific filtering. The buffer is > invalidated after reading. > > Introduce a for_each_brbe_entry() iterator to deduplicate bank > iteration between brbe_read_filtered_entries() and the snapshot. > > Signed-off-by: Puranjay Mohan <[email protected]> > --- > drivers/perf/arm_brbe.c | 127 ++++++++++++++++++++++++++++++++------- > drivers/perf/arm_brbe.h | 9 +++ > drivers/perf/arm_pmuv3.c | 5 +- > 3 files changed, 119 insertions(+), 22 deletions(-)
Reviewed-by: Rob Herring (Arm) <[email protected]>
