From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
Clark Williams <williams@redhat.com>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Ravi Bangoria <ravi.bangoria@linux.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 24/25] perf probe: Trace a magic number if variable is not found
Date: Tue, 19 Nov 2019 08:32:44 -0300 [thread overview]
Message-ID: <20191119113245.19593-25-acme@kernel.org> (raw)
In-Reply-To: <20191119113245.19593-1-acme@kernel.org>
From: Masami Hiramatsu <mhiramat@kernel.org>
Trace a magic number as immediate value if the target variable is not
found at some probe points which is based on one probe event.
This feature is good for the case if you trace a source code line with
some local variables, which is compiled into several instructions and
some of the variables are optimized out on some instructions.
Even if so, with this feature, perf probe trace a magic number instead
of such disappeared variables and fold those probes on one event.
E.g. without this patch:
# perf probe -D "pud_page_vaddr pud"
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
Failed to find 'pud' in this function.
p:probe/pud_page_vaddr _text+23480787 pud=%ax:x64
p:probe/pud_page_vaddr _text+23808453 pud=%bp:x64
p:probe/pud_page_vaddr _text+23558082 pud=%ax:x64
p:probe/pud_page_vaddr _text+328373 pud=%r8:x64
p:probe/pud_page_vaddr _text+348448 pud=%bx:x64
p:probe/pud_page_vaddr _text+23816818 pud=%bx:x64
With this patch:
# perf probe -D "pud_page_vaddr pud" | head
spurious_kernel_fault is blacklisted function, skip it.
vmalloc_fault is blacklisted function, skip it.
p:probe/pud_page_vaddr _text+23480787 pud=%ax:x64
p:probe/pud_page_vaddr _text+149051 pud=\deade12d:x64
p:probe/pud_page_vaddr _text+23808453 pud=%bp:x64
p:probe/pud_page_vaddr _text+315926 pud=\deade12d:x64
p:probe/pud_page_vaddr _text+23807209 pud=\deade12d:x64
p:probe/pud_page_vaddr _text+23557365 pud=%ax:x64
p:probe/pud_page_vaddr _text+314097 pud=%di:x64
p:probe/pud_page_vaddr _text+314015 pud=\deade12d:x64
p:probe/pud_page_vaddr _text+313893 pud=\deade12d:x64
p:probe/pud_page_vaddr _text+324083 pud=\deade12d:x64
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Link: http://lore.kernel.org/lkml/157406476931.24476.6261475888681844285.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/probe-event.c | 2 +-
tools/perf/util/probe-event.h | 3 ++
tools/perf/util/probe-finder.c | 62 +++++++++++++++++++++++++++++++---
tools/perf/util/probe-finder.h | 1 +
4 files changed, 63 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 8f963a193a5d..52b2d165453a 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -46,7 +46,7 @@
#define PERFPROBE_GROUP "probe"
bool probe_event_dry_run; /* Dry run flag */
-struct probe_conf probe_conf;
+struct probe_conf probe_conf = { .magic_num = DEFAULT_PROBE_MAGIC_NUM };
#define semantic_error(msg ...) pr_err("Semantic error :" msg)
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 96a319cd2378..4f0eb3a20c36 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -16,10 +16,13 @@ struct probe_conf {
bool no_inlines;
bool cache;
int max_probes;
+ unsigned long magic_num;
};
extern struct probe_conf probe_conf;
extern bool probe_event_dry_run;
+#define DEFAULT_PROBE_MAGIC_NUM 0xdeade12d /* u32: 3735937325 */
+
struct symbol;
/* kprobe-tracer and uprobe-tracer tracing point */
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 33e90054ad84..38d6cd22779f 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -536,6 +536,14 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
return 0;
}
+static void print_var_not_found(const char *varname)
+{
+ pr_err("Failed to find the location of the '%s' variable at this address.\n"
+ " Perhaps it has been optimized out.\n"
+ " Use -V with the --range option to show '%s' location range.\n",
+ varname, varname);
+}
+
/* Show a variables in kprobe event format */
static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
{
@@ -547,11 +555,11 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
&pf->sp_die, pf->machine, pf->tvar);
+ if (ret == -ENOENT && pf->skip_empty_arg)
+ /* This can be found in other place. skip it */
+ return 0;
if (ret == -ENOENT || ret == -EINVAL) {
- pr_err("Failed to find the location of the '%s' variable at this address.\n"
- " Perhaps it has been optimized out.\n"
- " Use -V with the --range option to show '%s' location range.\n",
- pf->pvar->var, pf->pvar->var);
+ print_var_not_found(pf->pvar->var);
} else if (ret == -ENOTSUP)
pr_err("Sorry, we don't support this variable location yet.\n");
else if (ret == 0 && pf->pvar->field) {
@@ -598,6 +606,8 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
/* Search again in global variables */
if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
0, &vr_die)) {
+ if (pf->skip_empty_arg)
+ return 0;
pr_warning("Failed to find '%s' in this function.\n",
pf->pvar->var);
ret = -ENOENT;
@@ -1384,6 +1394,44 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
return ret;
}
+static int fill_empty_trace_arg(struct perf_probe_event *pev,
+ struct probe_trace_event *tevs, int ntevs)
+{
+ char **valp;
+ char *type;
+ int i, j, ret;
+
+ for (i = 0; i < pev->nargs; i++) {
+ type = NULL;
+ for (j = 0; j < ntevs; j++) {
+ if (tevs[j].args[i].value) {
+ type = tevs[j].args[i].type;
+ break;
+ }
+ }
+ if (j == ntevs) {
+ print_var_not_found(pev->args[i].var);
+ return -ENOENT;
+ }
+ for (j = 0; j < ntevs; j++) {
+ valp = &tevs[j].args[i].value;
+ if (*valp)
+ continue;
+
+ ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
+ if (ret < 0)
+ return -ENOMEM;
+ /* Note that type can be NULL */
+ if (type) {
+ tevs[j].args[i].type = strdup(type);
+ if (!tevs[j].args[i].type)
+ return -ENOMEM;
+ }
+ }
+ }
+ return 0;
+}
+
/* Find probe_trace_events specified by perf_probe_event from debuginfo */
int debuginfo__find_trace_events(struct debuginfo *dbg,
struct perf_probe_event *pev,
@@ -1402,7 +1450,13 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
tf.tevs = *tevs;
tf.ntevs = 0;
+ if (pev->nargs != 0 && immediate_value_is_supported())
+ tf.pf.skip_empty_arg = true;
+
ret = debuginfo__find_probes(dbg, &tf.pf);
+ if (ret >= 0 && tf.pf.skip_empty_arg)
+ ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
+
if (ret < 0) {
for (i = 0; i < tf.ntevs; i++)
clear_probe_trace_event(&tf.tevs[i]);
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 670c477bf8cf..11be10080613 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -87,6 +87,7 @@ struct probe_finder {
unsigned int machine; /* Target machine arch */
struct perf_probe_arg *pvar; /* Current target variable */
struct probe_trace_arg *tvar; /* Current result variable */
+ bool skip_empty_arg; /* Skip non-exist args */
};
struct trace_event_finder {
--
2.21.0
next prev parent reply other threads:[~2019-11-19 11:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 11:32 [GIT PULL] perf/core improvements and fixes Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 01/25] perf vendor events arm64: Fix commas so PMU event files are valid JSON Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 02/25] perf vendor events power8: " Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 03/25] perf vendor events power9: " Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 04/25] perf scripts python: exported-sql-viewer.py: Fix use of TRUE with SQLite Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 05/25] perf maps: Purge the entries from maps->names in __maps__purge() Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 06/25] perf maps: Do not use an rbtree to sort by map name Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 07/25] perf map_groups: Add a front end cache for map lookups by name Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 08/25] perf map: No need to adjust the long name of modules Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 09/25] perf record: No need to process the synthesized MMAP events twice Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 10/25] perf machine: No need to check if kernel module maps pre-exist Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 11/25] perf map_groups: Auto sort maps by name, if needed Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 12/25] perf callchain: Fix segfault in thread__resolve_callchain_sample() Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 13/25] libtraceevent: Fix parsing of event %o and %X argument types Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 14/25] perf map: Use bitmap for booleans Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 15/25] perf map: Move seldom used ->flags field to second cacheline Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 16/25] x86/insn: perf tools: Add some instructions to the new instructions test Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 17/25] x86/insn: Add some Intel instructions to the opcode map Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 18/25] perf probe: Show correct statement line number by perf probe -l Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 19/25] perf probe: Verify given line is a representive line Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 20/25] perf probe: Do not show non representive lines by perf-probe -L Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 21/25] perf probe: Generate event name with line number Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 22/25] perf probe: Support multiprobe event Arnaldo Carvalho de Melo
2019-11-19 11:32 ` [PATCH 23/25] perf probe: Support DW_AT_const_value constant value Arnaldo Carvalho de Melo
2019-11-19 11:32 ` Arnaldo Carvalho de Melo [this message]
2019-11-19 11:32 ` [PATCH 25/25] perf parse: Report initial event parsing error Arnaldo Carvalho de Melo
2019-11-19 12:00 ` [GIT PULL] perf/core improvements and fixes Ingo Molnar
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