perf tools: Separate accounting of contexts and real addresses in a stack trace
The perf_sample->ip_callchain->nr value includes all the entries in the
ip_callchain->ip[] array, real addresses and PERF_CONTEXT_{KERNEL,USER,etc},
while what the user expects is that what is in the kernel.perf_event_max_stack
sysctl or in the upcoming per event perf_event_attr.sample_max_stack knob be
honoured in terms of IP addresses in the stack trace.
So match the kernel support and validate chain->nr taking into account
both kernel.perf_event_max_stack and kernel.perf_event_max_contexts_per_stack.
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: 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-mgx0jpzfdq4uq4abfa40byu0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 7970008..15982ce 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -549,6 +549,9 @@
if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
sysctl_perf_event_max_stack = value;
+ if (sysctl__read_int("kernel/perf_event_max_contexts_per_stack", &value) == 0)
+ sysctl_perf_event_max_contexts_per_stack = value;
+
cmd = extract_argv0_path(argv[0]);
if (!cmd)
cmd = "perf-help";
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 18dd96b..7ba9fad 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1811,9 +1811,9 @@
{
struct branch_stack *branch = sample->branch_stack;
struct ip_callchain *chain = sample->callchain;
- int chain_nr = min(max_stack, (int)chain->nr);
+ int chain_nr = chain->nr;
u8 cpumode = PERF_RECORD_MISC_USER;
- int i, j, err;
+ int i, j, err, nr_entries, nr_contexts;
int skip_idx = -1;
int first_call = 0;
@@ -1828,7 +1828,7 @@
* Based on DWARF debug information, some architectures skip
* a callchain entry saved by the kernel.
*/
- if (chain->nr < sysctl_perf_event_max_stack)
+ if (chain_nr < sysctl_perf_event_max_stack)
skip_idx = arch_skip_callchain_idx(thread, chain);
/*
@@ -1889,12 +1889,8 @@
}
check_calls:
- if (chain->nr > sysctl_perf_event_max_stack && (int)chain->nr > max_stack) {
- pr_warning("corrupted callchain. skipping...\n");
- return 0;
- }
-
- for (i = first_call; i < chain_nr; i++) {
+ for (i = first_call, nr_entries = 0, nr_contexts = 0;
+ i < chain_nr && nr_entries < max_stack; i++) {
u64 ip;
if (callchain_param.order == ORDER_CALLEE)
@@ -1908,6 +1904,14 @@
#endif
ip = chain->ips[j];
+ if (ip >= PERF_CONTEXT_MAX) {
+ if (++nr_contexts > sysctl_perf_event_max_contexts_per_stack)
+ goto out_corrupted_callchain;
+ } else {
+ if (++nr_entries > sysctl_perf_event_max_stack)
+ goto out_corrupted_callchain;
+ }
+
err = add_callchain_ip(thread, cursor, parent, root_al, &cpumode, ip);
if (err)
@@ -1915,6 +1919,10 @@
}
return 0;
+
+out_corrupted_callchain:
+ pr_warning("corrupted callchain. skipping...\n");
+ return 0;
}
static int unwind_entry(struct unwind_entry *entry, void *arg)
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index eab077a..23504ad 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -33,7 +33,8 @@
unsigned int page_size;
int cacheline_size;
-unsigned int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
+int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
+int sysctl_perf_event_max_contexts_per_stack = PERF_MAX_CONTEXTS_PER_STACK;
bool test_attr__enabled;
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 7651633..1e8c316 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -261,7 +261,8 @@
extern unsigned int page_size;
extern int cacheline_size;
-extern unsigned int sysctl_perf_event_max_stack;
+extern int sysctl_perf_event_max_stack;
+extern int sysctl_perf_event_max_contexts_per_stack;
struct parse_tag {
char tag;