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Commit a29d5c9b authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c85b0334

tools/perf/perf.c

+3 −0
Original line number Diff line number Diff line
@@ -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";

tools/perf/util/machine.c

+17 −9
Original line number Diff line number Diff line
@@ -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 @@ static int thread__resolve_callchain_sample(struct thread *thread, 
#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 @@ static int thread__resolve_callchain_sample(struct thread *thread, 
	}



	return 0;



out_corrupted_callchain:

	pr_warning("corrupted callchain. skipping...\n");

	return 0;

}



static int unwind_entry(struct unwind_entry *entry, void *arg)

tools/perf/util/util.c

+2 −1
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/util.h

+2 −1
Original line number Diff line number Diff line
@@ -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;