Commit 061c9916 authored by Saket Kumar Bhaskar's avatar Saket Kumar Bhaskar Committed by Ingo Molnar
Browse files

perf/hw_breakpoint: Return EOPNOTSUPP for unsupported breakpoint type 



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: default avatarSaket Kumar Bhaskar <skb99@linux.ibm.com>
Signed-off-by: default avatarIngo 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
parent ef2f7986

kernel/events/hw_breakpoint.c

+3 −2
Original line number Diff line number Diff line
@@ -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);