perf tools: Set the maximum allowed stack from /proc/sys/kernel/perf_event_max_stack

There is an upper limit to what tooling considers a valid callchain,
and it was tied to the hardcoded value in the kernel,
PERF_MAX_STACK_DEPTH (127), now that this can be tuned via a sysctl,
make it read it and use that as the upper limit, falling back to
PERF_MAX_STACK_DEPTH for kernels where this sysctl isn't present.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-yjqsd30nnkogvj5oyx9ghir9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

16 files changed, 28 insertions, 18 deletions

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 496d42cdf02b..ebaf849e30ef 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -248,7 +248,7 @@ OPTIONS
         Note that when using the --itrace option the synthesized callchain size
         will override this value if the synthesized callchain size is bigger.
 
-        Default: 127
+        Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
 
 -G::
 --inverted::
diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 4fc44c75263f..a856a1095893 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -267,7 +267,7 @@ include::itrace.txt[]
         Note that when using the --itrace option the synthesized callchain size
         will override this value if the synthesized callchain size is bigger.
 
-        Default: 127
+        Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
 
 --ns::
         Use 9 decimal places when displaying time (i.e. show the nanoseconds)
diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index 19f046f027cd..91d638df3a6b 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -177,7 +177,7 @@ Default is to monitor all CPUS.
         between information loss and faster processing especially for
         workloads that can have a very long callchain stack.
 
-        Default: 127
+        Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
 
 --ignore-callees=<regex>::
         Ignore callees of the function(s) matching the given regex.
diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index c075c002eaa4..6afe20121bc0 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -143,7 +143,7 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs.
         Implies '--call-graph dwarf' when --call-graph not present on the
         command line, on systems where DWARF unwinding was built in.
 
-        Default: 127
+        Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
 
 --min-stack::
         Set the stack depth limit when parsing the callchain, anything
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 1d5be0bd426f..8d9b88af901d 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -691,7 +691,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
                         .ordered_events  = true,
                         .ordering_requires_timestamps = true,
                 },
-                .max_stack               = PERF_MAX_STACK_DEPTH,
+                .max_stack               = sysctl_perf_event_max_stack,
                 .pretty_printing_style   = "normal",
                 .socket_filter           = -1,
         };
@@ -744,7 +744,7 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
         OPT_INTEGER(0, "max-stack", &report.max_stack,
                     "Set the maximum stack depth when parsing the callchain, "
                     "anything beyond the specified depth will be ignored. "
-                    "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+                    "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
         OPT_BOOLEAN('G', "inverted", &report.inverted_callchain,
                     "alias for inverted call graph"),
         OPT_CALLBACK(0, "ignore-callees", NULL, "regex",
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index f43b0c6f88f4..efca81679bb3 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2031,7 +2031,7 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
         OPT_UINTEGER(0, "max-stack", &scripting_max_stack,
                      "Set the maximum stack depth when parsing the callchain, "
                      "anything beyond the specified depth will be ignored. "
-                     "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+                     "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
         OPT_BOOLEAN('I', "show-info", &show_full_info,
                     "display extended information from perf.data file"),
         OPT_BOOLEAN('\0', "show-kernel-path", &symbol_conf.show_kernel_path,
@@ -2067,6 +2067,8 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
                 NULL
         };
 
+        scripting_max_stack = sysctl_perf_event_max_stack;
+
         setup_scripting();
 
         argc = parse_options_subcommand(argc, argv, options, script_subcommands, script_usage,
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index c130a11d3a0d..da18517b1d40 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1103,7 +1103,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
                         },
                         .proc_map_timeout    = 500,
                 },
-                .max_stack           = PERF_MAX_STACK_DEPTH,
+                .max_stack           = sysctl_perf_event_max_stack,
                 .sym_pcnt_filter     = 5,
         };
         struct record_opts *opts = &top.record_opts;
@@ -1171,7 +1171,7 @@ int cmd_top(int argc, const char **argv, const char *prefix __maybe_unused)
                     "Accumulate callchains of children and show total overhead as well"),
         OPT_INTEGER(0, "max-stack", &top.max_stack,
                     "Set the maximum stack depth when parsing the callchain. "
-                    "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+                    "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
         OPT_CALLBACK(0, "ignore-callees", NULL, "regex",
                    "ignore callees of these functions in call graphs",
                    report_parse_ignore_callees_opt),
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 48b00f042599..f4f3389c92c7 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -3106,7 +3106,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
         OPT_UINTEGER(0, "max-stack", &trace.max_stack,
                      "Set the maximum stack depth when parsing the callchain, "
                      "anything beyond the specified depth will be ignored. "
-                     "Default: " __stringify(PERF_MAX_STACK_DEPTH)),
+                     "Default: kernel.perf_event_max_stack or " __stringify(PERF_MAX_STACK_DEPTH)),
         OPT_UINTEGER(0, "proc-map-timeout", &trace.opts.proc_map_timeout,
                         "per thread proc mmap processing timeout in ms"),
         OPT_END()
@@ -3150,7 +3150,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
                 mmap_pages_user_set = false;
 
         if (trace.max_stack == UINT_MAX) {
-                trace.max_stack = PERF_MAX_STACK_DEPTH;
+                trace.max_stack = sysctl_perf_event_max_stack;
                 max_stack_user_set = false;
         }
 
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 7b2df2b46525..83ffe7cd7330 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -17,6 +17,7 @@
 #include <subcmd/parse-options.h>
 #include "util/bpf-loader.h"
 #include "util/debug.h"
+#include <api/fs/fs.h>
 #include <api/fs/tracing_path.h>
 #include <pthread.h>
 #include <stdlib.h>
@@ -533,6 +534,7 @@ int main(int argc, const char **argv)
 {
         const char *cmd;
         char sbuf[STRERR_BUFSIZE];
+        int value;
 
         /* libsubcmd init */
         exec_cmd_init("perf", PREFIX, PERF_EXEC_PATH, EXEC_PATH_ENVIRONMENT);
@@ -542,6 +544,9 @@ int main(int argc, const char **argv)
         page_size = sysconf(_SC_PAGE_SIZE);
         cacheline_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
 
+        if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
+                sysctl_perf_event_max_stack = value;
+
         cmd = extract_argv0_path(argv[0]);
         if (!cmd)
                 cmd = "perf-help";
diff --git a/tools/perf/tests/hists_cumulate.c b/tools/perf/tests/hists_cumulate.c
index ed5aa9eaeb6c..4a2bbff9b1ee 100644
--- a/tools/perf/tests/hists_cumulate.c
+++ b/tools/perf/tests/hists_cumulate.c
@@ -101,7 +101,7 @@ static int add_hist_entries(struct hists *hists, struct machine *machine)
                 if (machine__resolve(machine, &al, &sample) < 0)
                         goto out;
 
-                if (hist_entry_iter__add(&iter, &al, PERF_MAX_STACK_DEPTH,
+                if (hist_entry_iter__add(&iter, &al, sysctl_perf_event_max_stack,
                                          NULL) < 0) {
                         addr_location__put(&al);
                         goto out;
diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
index b825d24f8186..e846f8c42013 100644
--- a/tools/perf/tests/hists_filter.c
+++ b/tools/perf/tests/hists_filter.c
@@ -81,7 +81,7 @@ static int add_hist_entries(struct perf_evlist *evlist,
 
                         al.socket = fake_samples[i].socket;
                         if (hist_entry_iter__add(&iter, &al,
-                                                 PERF_MAX_STACK_DEPTH, NULL) < 0) {
+                                                 sysctl_perf_event_max_stack, NULL) < 0) {
                                 addr_location__put(&al);
                                 goto out;
                         }
diff --git a/tools/perf/tests/hists_output.c b/tools/perf/tests/hists_output.c
index d3556fbe8c5c..7cd8738e842f 100644
--- a/tools/perf/tests/hists_output.c
+++ b/tools/perf/tests/hists_output.c
@@ -67,7 +67,7 @@ static int add_hist_entries(struct hists *hists, struct machine *machine)
                 if (machine__resolve(machine, &al, &sample) < 0)
                         goto out;
 
-                if (hist_entry_iter__add(&iter, &al, PERF_MAX_STACK_DEPTH,
+                if (hist_entry_iter__add(&iter, &al, sysctl_perf_event_max_stack,
                                          NULL) < 0) {
                         addr_location__put(&al);
                         goto out;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 656c1d7ee7d4..2cb95bbf9ea6 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1764,7 +1764,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
                  */
                 int mix_chain_nr = i + 1 + lbr_nr + 1;
 
-                if (mix_chain_nr > PERF_MAX_STACK_DEPTH + PERF_MAX_BRANCH_DEPTH) {
+                if (mix_chain_nr > (int)sysctl_perf_event_max_stack + PERF_MAX_BRANCH_DEPTH) {
                         pr_warning("corrupted callchain. skipping...\n");
                         return 0;
                 }
@@ -1825,7 +1825,7 @@ 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 < PERF_MAX_STACK_DEPTH)
+        if (chain->nr < sysctl_perf_event_max_stack)
                 skip_idx = arch_skip_callchain_idx(thread, chain);
 
         /*
@@ -1886,7 +1886,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
         }
 
 check_calls:
-        if (chain->nr > PERF_MAX_STACK_DEPTH && (int)chain->nr > max_stack) {
+        if (chain->nr > sysctl_perf_event_max_stack && (int)chain->nr > max_stack) {
                 pr_warning("corrupted callchain. skipping...\n");
                 return 0;
         }
diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c b/tools/perf/util/scripting-engines/trace-event-perl.c
index ae1cebc307c5..62c7f6988e0e 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -265,7 +265,7 @@ static SV *perl_process_callchain(struct perf_sample *sample,
 
         if (thread__resolve_callchain(al->thread, &callchain_cursor, evsel,
                                       sample, NULL, NULL,
-                                      PERF_MAX_STACK_DEPTH) != 0) {
+                                      sysctl_perf_event_max_stack) != 0) {
                 pr_err("Failed to resolve callchain. Skipping\n");
                 goto exit;
         }
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9473d46c00bb..619ba2061b62 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -33,6 +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;
+
 bool test_attr__enabled;
 
 bool perf_host  = true;
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 26a924651e7b..88f607af1f47 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -267,6 +267,7 @@ void sighandler_dump_stack(int sig);
 
 extern unsigned int page_size;
 extern int cacheline_size;
+extern unsigned int sysctl_perf_event_max_stack;
 
 struct parse_tag {
         char tag;