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Subject[PATCH v3 07/11] perf: Add breakpoint information to siginfo on SIGTRAP
From
Encode information from breakpoint attributes into siginfo_t, which
helps disambiguate which breakpoint fired.

Note, providing the event fd may be unreliable, since the event may have
been modified (via PERF_EVENT_IOC_MODIFY_ATTRIBUTES) between the event
triggering and the signal being delivered to user space.

Signed-off-by: Marco Elver <elver@google.com>
---
v2:
* Add comment about si_perf==0.
---
kernel/events/core.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1e4c949bf75f..0316d39e8c8f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6399,6 +6399,22 @@ static void perf_sigtrap(struct perf_event *event)
info.si_signo = SIGTRAP;
info.si_code = TRAP_PERF;
info.si_errno = event->attr.type;
+
+ switch (event->attr.type) {
+ case PERF_TYPE_BREAKPOINT:
+ info.si_addr = (void *)(unsigned long)event->attr.bp_addr;
+ info.si_perf = (event->attr.bp_len << 16) | (u64)event->attr.bp_type;
+ break;
+ default:
+ /*
+ * No additional info set (si_perf == 0).
+ *
+ * Adding new cases for event types to set si_perf to a
+ * non-constant value must ensure that si_perf != 0.
+ */
+ break;
+ }
+
force_sig_info(&info);
}

--
2.31.0.291.g576ba9dcdaf-goog
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