[PATCH v2 0/2] perf/x86: Limit branch snapshots to valid entries

[Sandipan Das]

Sashiko reported that the vendor-specific branch snapshot callbacks
used by bpf_get_branch_snapshot() copy up to x86_pmu.lbr_nr entries
from cpuc->lbr_entries[], regardless of how many valid entries the
last LBR read produced. This makes BPF programs read stale or invalid
branch records. Patch 1 addresses AMD and patch 2 addresses Intel.

Previous version(s) can be found at
v1: https://lore.kernel.org/all/20261007181002.4005262-1-sandipan.das@xxxxxxx/

Changes in v2:
  * Include a fix for Intel LBR.
  * Add Tested-by from Dapeng to the Intel fix.
    https://lore.kernel.org/all/eb6c7bda-0dcf-4fac-ad69-9f5b24abc21b@xxxxxxxxxxxxxxx/

Sandipan Das (2):
  perf/x86/amd/lbr: Limit branch snapshots to valid entries
  perf/x86/intel/lbr: Limit branch snapshots to valid entries

 arch/x86/events/amd/core.c   | 2 +-
 arch/x86/events/amd/lbr.c    | 4 +++-
 arch/x86/events/intel/core.c | 2 +-
 arch/x86/events/intel/lbr.c  | 4 +++-
 4 files changed, 8 insertions(+), 4 deletions(-)

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2.53.0