6.6-stable review patch. If anyone has any objections, please let me know.
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From: Saket Kumar Bhaskar skb99@linux.ibm.com
[ Upstream commit 061c991697062f3bf87b72ed553d1d33a0e370dd ]
Currently, __reserve_bp_slot() returns -ENOSPC for unsupported breakpoint types on the architecture. For example, powerpc does not support hardware instruction breakpoints. This causes the perf_skip BPF selftest to fail, as neither ENOENT nor EOPNOTSUPP is returned by perf_event_open for unsupported breakpoint types. As a result, the test that should be skipped for this arch is not correctly identified.
To resolve this, hw_breakpoint_event_init() should exit early by checking for unsupported breakpoint types using hw_breakpoint_slots_cached() and return the appropriate error (-EOPNOTSUPP).
Signed-off-by: Saket Kumar Bhaskar skb99@linux.ibm.com Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Marco Elver elver@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Ian Rogers irogers@google.com Cc: Frederic Weisbecker fweisbec@gmail.com Link: https://lore.kernel.org/r/20250303092451.1862862-1-skb99@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/hw_breakpoint.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 6c2cb4e4f48da..8f3f624419aa9 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -950,9 +950,10 @@ static int hw_breakpoint_event_init(struct perf_event *bp) return -ENOENT;
/* - * no branch sampling for breakpoint events + * Check if breakpoint type is supported before proceeding. + * Also, no branch sampling for breakpoint events. */ - if (has_branch_stack(bp)) + if (!hw_breakpoint_slots_cached(find_slot_idx(bp->attr.bp_type)) || has_branch_stack(bp)) return -EOPNOTSUPP;
err = register_perf_hw_breakpoint(bp);