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perf tools: Separate accounting of contexts and real addresses in a stack trace

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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>
This commit is contained in:
Arnaldo Carvalho de Melo 2016-05-16 21:16:54 -03:00
parent c85b033496
commit a29d5c9b81
4 changed files with 24 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
tools/perf/perf.c
View File

@ -549,6 +549,9 @@ int main(int argc, const char **argv)
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";

26
tools/perf/util/machine.c
View File

@ -1811,9 +1811,9 @@ static int thread__resolve_callchain_sample(struct thread *thread,
{
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 @@ static int thread__resolve_callchain_sample(struct thread *thread,
* 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 @@ static int thread__resolve_callchain_sample(struct thread *thread,
}
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 @@ check_calls:
#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 @@ check_calls:
}
return 0;
out_corrupted_callchain:
pr_warning("corrupted callchain. skipping...\n");
return 0;
}
static int unwind_entry(struct unwind_entry *entry, void *arg)

3
tools/perf/util/util.c
View File

@ -33,7 +33,8 @@ struct callchain_param callchain_param = {
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;

3
tools/perf/util/util.h
View File

@ -261,7 +261,8 @@ void sighandler_dump_stack(int sig);
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;