The following commit has been merged into the perf/core branch of tip:
Commit-ID: 66f69b2197167cb99330c77a550da50f1f597abc
Gitweb: https://git.kernel.org/tip/66f69b2197167cb99330c77a550da50f1f597abc
Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Mon, 18 Nov 2019 17:12:40 +09:00
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Mon, 18 Nov 2019 19:08:02 -03:00
perf probe: Support DW_AT_const_value constant value
Support DW_AT_const_value for variable assignment instead of location.
Note that this requires ftrace supporting immediate value.
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/157406476012.24476.16096289871757175775.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/probe-file.c | 7 +++++++
tools/perf/util/probe-file.h | 1 +
tools/perf/util/probe-finder.c | 11 +++++++++++
3 files changed, 19 insertions(+)
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index a63f1a1..5003ba4 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -1008,6 +1008,7 @@ enum ftrace_readme {
FTRACE_README_UPROBE_REF_CTR,
FTRACE_README_USER_ACCESS,
FTRACE_README_MULTIPROBE_EVENT,
+ FTRACE_README_IMMEDIATE_VALUE,
FTRACE_README_END,
};
@@ -1022,6 +1023,7 @@ static struct {
DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]<offset>*"),
DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
+ DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
};
static bool scan_ftrace_readme(enum ftrace_readme type)
@@ -1092,3 +1094,8 @@ bool multiprobe_event_is_supported(void)
{
return scan_ftrace_readme(FTRACE_README_MULTIPROBE_EVENT);
}
+
+bool immediate_value_is_supported(void)
+{
+ return scan_ftrace_readme(FTRACE_README_IMMEDIATE_VALUE);
+}
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index 850d1b5..0dba88c 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -72,6 +72,7 @@ bool kretprobe_offset_is_supported(void);
bool uprobe_ref_ctr_is_supported(void);
bool user_access_is_supported(void);
bool multiprobe_event_is_supported(void);
+bool immediate_value_is_supported(void);
#else /* ! HAVE_LIBELF_SUPPORT */
static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused, struct nsinfo *nsi __maybe_unused)
{
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index f12ad50..33e9005 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -177,6 +177,17 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
goto static_var;
+ /* Constant value */
+ if (dwarf_attr(vr_die, DW_AT_const_value, &attr) &&
+ immediate_value_is_supported()) {
+ Dwarf_Sword snum;
+
+ dwarf_formsdata(&attr, &snum);
+ ret = asprintf(&tvar->value, "\\%ld", (long)snum);
+
+ return ret < 0 ? -ENOMEM : 0;
+ }
+
/* TODO: handle more than 1 exprs */
if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
return -EINVAL; /* Broken DIE ? */
|