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perf: Copy perf_event_attr::sig_data on modification

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The intent has always been that perf_event_attr::sig_data should also be
modifiable along with PERF_EVENT_IOC_MODIFY_ATTRIBUTES, because it is
observable by user space if SIGTRAP on events is requested.

Currently only PERF_TYPE_BREAKPOINT is modifiable, and explicitly copies
relevant breakpoint-related attributes in hw_breakpoint_copy_attr().
This misses copying perf_event_attr::sig_data.

Since sig_data is not specific to PERF_TYPE_BREAKPOINT, introduce a
helper to copy generic event-type-independent attributes on
modification.

Fixes: 97ba62b278 ("perf: Add support for SIGTRAP on perf events")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/20220131103407.1971678-1-elver@google.com
This commit is contained in:
Marco Elver 2022-01-31 11:34:05 +01:00 committed by Peter Zijlstra
parent a01994f5e5
commit 3c25fc97f5
1 changed files with 16 additions and 0 deletions
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16
kernel/events/core.c
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@ -3238,6 +3238,15 @@ static int perf_event_modify_breakpoint(struct perf_event *bp,
return err;
}
/*
* Copy event-type-independent attributes that may be modified.
*/
static void perf_event_modify_copy_attr(struct perf_event_attr *to,
const struct perf_event_attr *from)
{
to->sig_data = from->sig_data;
}
static int perf_event_modify_attr(struct perf_event *event,
struct perf_event_attr *attr)
{
@ -3260,10 +3269,17 @@ static int perf_event_modify_attr(struct perf_event *event,
WARN_ON_ONCE(event->ctx->parent_ctx);
mutex_lock(&event->child_mutex);
/*
* Event-type-independent attributes must be copied before event-type
* modification, which will validate that final attributes match the
* source attributes after all relevant attributes have been copied.
*/
perf_event_modify_copy_attr(&event->attr, attr);
err = func(event, attr);
if (err)
goto out;
list_for_each_entry(child, &event->child_list, child_list) {
perf_event_modify_copy_attr(&child->attr, attr);
err = func(child, attr);
if (err)
goto out;