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| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2016-04-28 13:16:33 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2016-05-30 12:41:44 -0300 |
| commit | 97c79a38cd454602645f0470ffb444b3b75ce574 (patch) | |
| tree | 40e427e9c76c5e4e1a5f2da1f3ec81e34223fa9b /kernel/events/callchain.c | |
| parent | 480ca357fd7f86a381a5b35a8157aa176eddbed4 (diff) | |
| download | linux-97c79a38cd454602645f0470ffb444b3b75ce574.tar.bz2 | |
perf core: Per event callchain limit
Additionally to being able to control the system wide maximum depth via
/proc/sys/kernel/perf_event_max_stack, now we are able to ask for
different depths per event, using perf_event_attr.sample_max_stack for
that.
This uses an u16 hole at the end of perf_event_attr, that, when
perf_event_attr.sample_type has the PERF_SAMPLE_CALLCHAIN, if
sample_max_stack is zero, means use perf_event_max_stack, otherwise
it'll be bounds checked under callchain_mutex.
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/n/tip-kolmn1yo40p7jhswxwrc7rrd@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'kernel/events/callchain.c')
| -rw-r--r-- | kernel/events/callchain.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 179ef4640964..e9fdb5203de5 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -104,7 +104,7 @@ fail: return -ENOMEM; } -int get_callchain_buffers(void) +int get_callchain_buffers(int event_max_stack) { int err = 0; int count; @@ -121,6 +121,15 @@ int get_callchain_buffers(void) /* If the allocation failed, give up */ if (!callchain_cpus_entries) err = -ENOMEM; + /* + * If requesting per event more than the global cap, + * return a different error to help userspace figure + * this out. + * + * And also do it here so that we have &callchain_mutex held. + */ + if (event_max_stack > sysctl_perf_event_max_stack) + err = -EOVERFLOW; goto exit; } @@ -174,11 +183,12 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) bool user = !event->attr.exclude_callchain_user; /* Disallow cross-task user callchains. */ bool crosstask = event->ctx->task && event->ctx->task != current; + const u32 max_stack = event->attr.sample_max_stack; if (!kernel && !user) return NULL; - return get_perf_callchain(regs, 0, kernel, user, sysctl_perf_event_max_stack, crosstask, true); + return get_perf_callchain(regs, 0, kernel, user, max_stack, crosstask, true); } struct perf_callchain_entry * |