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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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