From 061c991697062f3bf87b72ed553d1d33a0e370dd Mon Sep 17 00:00:00 2001 From: Saket Kumar Bhaskar Date: Mon, 3 Mar 2025 14:54:51 +0530 Subject: [PATCH] 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: Saket Kumar Bhaskar Signed-off-by: Ingo Molnar Cc: Marco Elver Cc: Dmitry Vyukov Cc: Ian Rogers Cc: Frederic Weisbecker Link: https://lore.kernel.org/r/20250303092451.1862862-1-skb99@linux.ibm.com --- 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 bc4a61029b6dc..8ec2cb6889038 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);