The vdso dumped from process memory (in buildid-cache) lacks debugging
info. To annotate vdso symbols with source lines we need specify a
debugging version.
For x86, we can find them from your local build as
arch/x86/entry/vdso/vdso{32,64}.so.dbg. Or they may reside in
/lib/modules/<version>/vdso/vdso{32,64}.so on Ubuntu. But notice that
the buildid has to match.
$ sudo perf record -a
$ sudo perf report --objdump=llvm-objdump \
--vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg
When doing cross platform analysis, we also need specify the vdso path if
we are interested in its symbols.
Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
tools/perf/builtin-annotate.c | 2 +
tools/perf/builtin-c2c.c | 2 +
tools/perf/builtin-inject.c | 2 +
tools/perf/builtin-report.c | 2 +
tools/perf/builtin-script.c | 2 +
tools/perf/builtin-top.c | 2 +
tools/perf/util/symbol.c | 74 +++++++++++++++++++++++++++++++++++
tools/perf/util/symbol_conf.h | 5 +++
8 files changed, 91 insertions(+)
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 50d2fb222d48..ff466882065d 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -742,6 +742,8 @@ int cmd_annotate(int argc, const char **argv)
"file", "vmlinux pathname"),
OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
"load module symbols - WARNING: use only with -k and LIVE kernel"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_BOOLEAN('l', "print-line", &annotate_opts.print_lines,
"print matching source lines (may be slow)"),
OPT_BOOLEAN('P', "full-paths", &annotate_opts.full_path,
diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index c157bd31f2e5..4764f9139661 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -3018,6 +3018,8 @@ static int perf_c2c__report(int argc, const char **argv)
const struct option options[] = {
OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
"file", "vmlinux pathname"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_STRING('i', "input", &input_name, "file",
"the input file to process"),
OPT_INCR('N', "node-info", &c2c.node_info,
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index a212678d47be..e774e83d0a0f 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -2247,6 +2247,8 @@ int cmd_inject(int argc, const char **argv)
"don't load vmlinux even if found"),
OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name, "file",
"kallsyms pathname"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_BOOLEAN('f', "force", &data.force, "don't complain, do it"),
OPT_CALLBACK_OPTARG(0, "itrace", &inject.itrace_synth_opts,
NULL, "opts", "Instruction Tracing options\n"
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 69618fb0110b..a64b48460dce 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -1324,6 +1324,8 @@ int cmd_report(int argc, const char **argv)
"don't load vmlinux even if found"),
OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
"file", "kallsyms pathname"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"),
OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
"load module symbols - WARNING: use only with -k and LIVE kernel"),
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index c16224b1fef3..2e358922a8d1 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3965,6 +3965,8 @@ int cmd_script(int argc, const char **argv)
"file", "vmlinux pathname"),
OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
"file", "kallsyms pathname"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_BOOLEAN('G', "hide-call-graph", &no_callchain,
"When printing symbols do not display call chain"),
OPT_CALLBACK(0, "symfs", NULL, "directory",
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 1d6aef51c122..a3cce4e76eb9 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1479,6 +1479,8 @@ int cmd_top(int argc, const char **argv)
"file", "kallsyms pathname"),
OPT_BOOLEAN('K', "hide_kernel_symbols", &top.hide_kernel_symbols,
"hide kernel symbols"),
+ OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
+ parse_vdso_pathnames),
OPT_CALLBACK('m', "mmap-pages", &opts->mmap_pages, "pages",
"number of mmap data pages", evlist__parse_mmap_pages),
OPT_INTEGER('r', "realtime", &top.realtime_prio,
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 9e5940b5bc59..8d040039a7ce 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -19,6 +19,7 @@
#include "build-id.h"
#include "cap.h"
#include "dso.h"
+#include "vdso.h"
#include "util.h" // lsdir()
#include "debug.h"
#include "event.h"
@@ -44,6 +45,7 @@
static int dso__load_kernel_sym(struct dso *dso, struct map *map);
static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
+static int dso__load_vdso_sym(struct dso *dso, struct map *map);
static bool symbol__is_idle(const char *name);
int vmlinux_path__nr_entries;
@@ -1833,6 +1835,12 @@ int dso__load(struct dso *dso, struct map *map)
goto out;
}
+ if (dso__is_vdso(dso)) {
+ ret = dso__load_vdso_sym(dso, map);
+ if (ret > 0)
+ goto out;
+ }
+
dso__set_adjust_symbols(dso, false);
if (perfmap) {
@@ -2349,6 +2357,72 @@ static int vmlinux_path__init(struct perf_env *env)
return -1;
}
+int parse_vdso_pathnames(const struct option *opt __maybe_unused,
+ const char *arg, int unset __maybe_unused)
+{
+ char *tmp, *tok, *str = strdup(arg);
+ unsigned int i = 0;
+
+ for (tok = strtok_r(str, ",", &tmp); tok && i < ARRAY_SIZE(symbol_conf.vdso_name);
+ tok = strtok_r(NULL, ",", &tmp)) {
+ symbol_conf.vdso_name[i++] = strdup(tok);
+ }
+
+ free(str);
+ return 0;
+}
+
+static int dso__load_vdso(struct dso *dso, struct map *map,
+ const char *vdso)
+{
+ int err = -1;
+ struct symsrc ss;
+ char symfs_vdso[PATH_MAX];
+
+ if (vdso[0] == '/')
+ snprintf(symfs_vdso, sizeof(symfs_vdso), "%s", vdso);
+ else
+ symbol__join_symfs(symfs_vdso, vdso);
+
+ if (symsrc__init(&ss, dso, symfs_vdso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO))
+ return -1;
+
+ /*
+ * dso__load_sym() may copy 'dso' which will result in the copies having
+ * an incorrect long name unless we set it here first.
+ */
+ dso__set_long_name(dso, vdso, false);
+ dso__set_binary_type(dso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO);
+
+ err = dso__load_sym(dso, map, &ss, &ss, 0);
+ symsrc__destroy(&ss);
+
+ if (err > 0) {
+ dso__set_loaded(dso);
+ pr_debug("Using %s for %s symbols\n", symfs_vdso, dso__short_name(dso));
+ }
+
+ return err;
+}
+
+static int dso__load_vdso_sym(struct dso *dso, struct map *map)
+{
+ int ret;
+
+ if (!dso__is_vdso(dso))
+ return -1;
+
+ for (unsigned int i = 0; i < ARRAY_SIZE(symbol_conf.vdso_name); i++) {
+ if (symbol_conf.vdso_name[i] != NULL) {
+ ret = dso__load_vdso(dso, map, symbol_conf.vdso_name[i]);
+ if (ret > 0)
+ return ret;
+ }
+ }
+
+ return -1;
+}
+
int setup_list(struct strlist **list, const char *list_str,
const char *list_name)
{
diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
index c114bbceef40..108356e3c981 100644
--- a/tools/perf/util/symbol_conf.h
+++ b/tools/perf/util/symbol_conf.h
@@ -3,6 +3,7 @@
#define __PERF_SYMBOL_CONF 1
#include <stdbool.h>
+#include <subcmd/parse-options.h>
struct strlist;
struct intlist;
@@ -55,6 +56,7 @@ struct symbol_conf {
const char *default_guest_vmlinux_name,
*default_guest_kallsyms,
*default_guest_modules;
+ const char *vdso_name[2];
const char *guestmount;
const char *dso_list_str,
*comm_list_str,
@@ -85,4 +87,7 @@ struct symbol_conf {
extern struct symbol_conf symbol_conf;
+int parse_vdso_pathnames(const struct option *opt __maybe_unused,
+ const char *arg, int unset __maybe_unused);
+
#endif // __PERF_SYMBOL_CONF
--
2.34.1On 13/06/24 09:35, Changbin Du wrote:
> The vdso dumped from process memory (in buildid-cache) lacks debugging
> info. To annotate vdso symbols with source lines we need specify a
> debugging version.
>
> For x86, we can find them from your local build as
> arch/x86/entry/vdso/vdso{32,64}.so.dbg. Or they may reside in
> /lib/modules/<version>/vdso/vdso{32,64}.so on Ubuntu. But notice that
> the buildid has to match.
>
> $ sudo perf record -a
> $ sudo perf report --objdump=llvm-objdump \
> --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg
>
> When doing cross platform analysis, we also need specify the vdso path if
> we are interested in its symbols.
We already have logic to find debug files, and to deal with a symbol source
(syms_ss) and runtime symbol source (runtime_ss).
Can't we make that work transparently for vdso so that the user does
not have to.
>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> ---
> tools/perf/builtin-annotate.c | 2 +
> tools/perf/builtin-c2c.c | 2 +
> tools/perf/builtin-inject.c | 2 +
> tools/perf/builtin-report.c | 2 +
> tools/perf/builtin-script.c | 2 +
> tools/perf/builtin-top.c | 2 +
> tools/perf/util/symbol.c | 74 +++++++++++++++++++++++++++++++++++
> tools/perf/util/symbol_conf.h | 5 +++
> 8 files changed, 91 insertions(+)
>
> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> index 50d2fb222d48..ff466882065d 100644
> --- a/tools/perf/builtin-annotate.c
> +++ b/tools/perf/builtin-annotate.c
> @@ -742,6 +742,8 @@ int cmd_annotate(int argc, const char **argv)
> "file", "vmlinux pathname"),
> OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
> "load module symbols - WARNING: use only with -k and LIVE kernel"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_BOOLEAN('l', "print-line", &annotate_opts.print_lines,
> "print matching source lines (may be slow)"),
> OPT_BOOLEAN('P', "full-paths", &annotate_opts.full_path,
> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index c157bd31f2e5..4764f9139661 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
> @@ -3018,6 +3018,8 @@ static int perf_c2c__report(int argc, const char **argv)
> const struct option options[] = {
> OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
> "file", "vmlinux pathname"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_STRING('i', "input", &input_name, "file",
> "the input file to process"),
> OPT_INCR('N', "node-info", &c2c.node_info,
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index a212678d47be..e774e83d0a0f 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -2247,6 +2247,8 @@ int cmd_inject(int argc, const char **argv)
> "don't load vmlinux even if found"),
> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name, "file",
> "kallsyms pathname"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_BOOLEAN('f', "force", &data.force, "don't complain, do it"),
> OPT_CALLBACK_OPTARG(0, "itrace", &inject.itrace_synth_opts,
> NULL, "opts", "Instruction Tracing options\n"
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index 69618fb0110b..a64b48460dce 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -1324,6 +1324,8 @@ int cmd_report(int argc, const char **argv)
> "don't load vmlinux even if found"),
> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
> "file", "kallsyms pathname"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"),
> OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
> "load module symbols - WARNING: use only with -k and LIVE kernel"),
> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> index c16224b1fef3..2e358922a8d1 100644
> --- a/tools/perf/builtin-script.c
> +++ b/tools/perf/builtin-script.c
> @@ -3965,6 +3965,8 @@ int cmd_script(int argc, const char **argv)
> "file", "vmlinux pathname"),
> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
> "file", "kallsyms pathname"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_BOOLEAN('G', "hide-call-graph", &no_callchain,
> "When printing symbols do not display call chain"),
> OPT_CALLBACK(0, "symfs", NULL, "directory",
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 1d6aef51c122..a3cce4e76eb9 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -1479,6 +1479,8 @@ int cmd_top(int argc, const char **argv)
> "file", "kallsyms pathname"),
> OPT_BOOLEAN('K', "hide_kernel_symbols", &top.hide_kernel_symbols,
> "hide kernel symbols"),
> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> + parse_vdso_pathnames),
> OPT_CALLBACK('m', "mmap-pages", &opts->mmap_pages, "pages",
> "number of mmap data pages", evlist__parse_mmap_pages),
> OPT_INTEGER('r', "realtime", &top.realtime_prio,
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 9e5940b5bc59..8d040039a7ce 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -19,6 +19,7 @@
> #include "build-id.h"
> #include "cap.h"
> #include "dso.h"
> +#include "vdso.h"
> #include "util.h" // lsdir()
> #include "debug.h"
> #include "event.h"
> @@ -44,6 +45,7 @@
>
> static int dso__load_kernel_sym(struct dso *dso, struct map *map);
> static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
> +static int dso__load_vdso_sym(struct dso *dso, struct map *map);
> static bool symbol__is_idle(const char *name);
>
> int vmlinux_path__nr_entries;
> @@ -1833,6 +1835,12 @@ int dso__load(struct dso *dso, struct map *map)
> goto out;
> }
>
> + if (dso__is_vdso(dso)) {
> + ret = dso__load_vdso_sym(dso, map);
> + if (ret > 0)
> + goto out;
> + }
> +
> dso__set_adjust_symbols(dso, false);
>
> if (perfmap) {
> @@ -2349,6 +2357,72 @@ static int vmlinux_path__init(struct perf_env *env)
> return -1;
> }
>
> +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
> + const char *arg, int unset __maybe_unused)
> +{
> + char *tmp, *tok, *str = strdup(arg);
> + unsigned int i = 0;
> +
> + for (tok = strtok_r(str, ",", &tmp); tok && i < ARRAY_SIZE(symbol_conf.vdso_name);
> + tok = strtok_r(NULL, ",", &tmp)) {
> + symbol_conf.vdso_name[i++] = strdup(tok);
> + }
> +
> + free(str);
> + return 0;
> +}
> +
> +static int dso__load_vdso(struct dso *dso, struct map *map,
> + const char *vdso)
> +{
> + int err = -1;
> + struct symsrc ss;
> + char symfs_vdso[PATH_MAX];
> +
> + if (vdso[0] == '/')
> + snprintf(symfs_vdso, sizeof(symfs_vdso), "%s", vdso);
> + else
> + symbol__join_symfs(symfs_vdso, vdso);
> +
> + if (symsrc__init(&ss, dso, symfs_vdso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO))
> + return -1;
> +
> + /*
> + * dso__load_sym() may copy 'dso' which will result in the copies having
> + * an incorrect long name unless we set it here first.
> + */
> + dso__set_long_name(dso, vdso, false);
> + dso__set_binary_type(dso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO);
> +
> + err = dso__load_sym(dso, map, &ss, &ss, 0);
> + symsrc__destroy(&ss);
> +
> + if (err > 0) {
> + dso__set_loaded(dso);
> + pr_debug("Using %s for %s symbols\n", symfs_vdso, dso__short_name(dso));
> + }
> +
> + return err;
> +}
> +
> +static int dso__load_vdso_sym(struct dso *dso, struct map *map)
> +{
> + int ret;
> +
> + if (!dso__is_vdso(dso))
> + return -1;
> +
> + for (unsigned int i = 0; i < ARRAY_SIZE(symbol_conf.vdso_name); i++) {
> + if (symbol_conf.vdso_name[i] != NULL) {
> + ret = dso__load_vdso(dso, map, symbol_conf.vdso_name[i]);
> + if (ret > 0)
> + return ret;
> + }
> + }
> +
> + return -1;
> +}
> +
> int setup_list(struct strlist **list, const char *list_str,
> const char *list_name)
> {
> diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
> index c114bbceef40..108356e3c981 100644
> --- a/tools/perf/util/symbol_conf.h
> +++ b/tools/perf/util/symbol_conf.h
> @@ -3,6 +3,7 @@
> #define __PERF_SYMBOL_CONF 1
>
> #include <stdbool.h>
> +#include <subcmd/parse-options.h>
>
> struct strlist;
> struct intlist;
> @@ -55,6 +56,7 @@ struct symbol_conf {
> const char *default_guest_vmlinux_name,
> *default_guest_kallsyms,
> *default_guest_modules;
> + const char *vdso_name[2];
> const char *guestmount;
> const char *dso_list_str,
> *comm_list_str,
> @@ -85,4 +87,7 @@ struct symbol_conf {
>
> extern struct symbol_conf symbol_conf;
>
> +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
> + const char *arg, int unset __maybe_unused);
> +
> #endif // __PERF_SYMBOL_CONF
On Thu, Jun 13, 2024 at 11:23:26AM +0300, Adrian Hunter wrote:
> On 13/06/24 09:35, Changbin Du wrote:
> > The vdso dumped from process memory (in buildid-cache) lacks debugging
> > info. To annotate vdso symbols with source lines we need specify a
> > debugging version.
> >
> > For x86, we can find them from your local build as
> > arch/x86/entry/vdso/vdso{32,64}.so.dbg. Or they may reside in
> > /lib/modules/<version>/vdso/vdso{32,64}.so on Ubuntu. But notice that
> > the buildid has to match.
> >
> > $ sudo perf record -a
> > $ sudo perf report --objdump=llvm-objdump \
> > --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg
> >
> > When doing cross platform analysis, we also need specify the vdso path if
> > we are interested in its symbols.
>
> We already have logic to find debug files, and to deal with a symbol source
> (syms_ss) and runtime symbol source (runtime_ss).
>
> Can't we make that work transparently for vdso so that the user does
> not have to.
>
For Ubuntu, we can find the debug files of vdso in
/lib/modules/<version>/vdso/vdso{32,64}.so. These two are debug version.
For local build, seems vdso{32,64}.so.dbg are not installed in /lib/modules/ nor
other locations.
> >
> > Signed-off-by: Changbin Du <changbin.du@huawei.com>
> > ---
> > tools/perf/builtin-annotate.c | 2 +
> > tools/perf/builtin-c2c.c | 2 +
> > tools/perf/builtin-inject.c | 2 +
> > tools/perf/builtin-report.c | 2 +
> > tools/perf/builtin-script.c | 2 +
> > tools/perf/builtin-top.c | 2 +
> > tools/perf/util/symbol.c | 74 +++++++++++++++++++++++++++++++++++
> > tools/perf/util/symbol_conf.h | 5 +++
> > 8 files changed, 91 insertions(+)
> >
> > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> > index 50d2fb222d48..ff466882065d 100644
> > --- a/tools/perf/builtin-annotate.c
> > +++ b/tools/perf/builtin-annotate.c
> > @@ -742,6 +742,8 @@ int cmd_annotate(int argc, const char **argv)
> > "file", "vmlinux pathname"),
> > OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
> > "load module symbols - WARNING: use only with -k and LIVE kernel"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_BOOLEAN('l', "print-line", &annotate_opts.print_lines,
> > "print matching source lines (may be slow)"),
> > OPT_BOOLEAN('P', "full-paths", &annotate_opts.full_path,
> > diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> > index c157bd31f2e5..4764f9139661 100644
> > --- a/tools/perf/builtin-c2c.c
> > +++ b/tools/perf/builtin-c2c.c
> > @@ -3018,6 +3018,8 @@ static int perf_c2c__report(int argc, const char **argv)
> > const struct option options[] = {
> > OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
> > "file", "vmlinux pathname"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_STRING('i', "input", &input_name, "file",
> > "the input file to process"),
> > OPT_INCR('N', "node-info", &c2c.node_info,
> > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> > index a212678d47be..e774e83d0a0f 100644
> > --- a/tools/perf/builtin-inject.c
> > +++ b/tools/perf/builtin-inject.c
> > @@ -2247,6 +2247,8 @@ int cmd_inject(int argc, const char **argv)
> > "don't load vmlinux even if found"),
> > OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name, "file",
> > "kallsyms pathname"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_BOOLEAN('f', "force", &data.force, "don't complain, do it"),
> > OPT_CALLBACK_OPTARG(0, "itrace", &inject.itrace_synth_opts,
> > NULL, "opts", "Instruction Tracing options\n"
> > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> > index 69618fb0110b..a64b48460dce 100644
> > --- a/tools/perf/builtin-report.c
> > +++ b/tools/perf/builtin-report.c
> > @@ -1324,6 +1324,8 @@ int cmd_report(int argc, const char **argv)
> > "don't load vmlinux even if found"),
> > OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
> > "file", "kallsyms pathname"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"),
> > OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
> > "load module symbols - WARNING: use only with -k and LIVE kernel"),
> > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> > index c16224b1fef3..2e358922a8d1 100644
> > --- a/tools/perf/builtin-script.c
> > +++ b/tools/perf/builtin-script.c
> > @@ -3965,6 +3965,8 @@ int cmd_script(int argc, const char **argv)
> > "file", "vmlinux pathname"),
> > OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
> > "file", "kallsyms pathname"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_BOOLEAN('G', "hide-call-graph", &no_callchain,
> > "When printing symbols do not display call chain"),
> > OPT_CALLBACK(0, "symfs", NULL, "directory",
> > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> > index 1d6aef51c122..a3cce4e76eb9 100644
> > --- a/tools/perf/builtin-top.c
> > +++ b/tools/perf/builtin-top.c
> > @@ -1479,6 +1479,8 @@ int cmd_top(int argc, const char **argv)
> > "file", "kallsyms pathname"),
> > OPT_BOOLEAN('K', "hide_kernel_symbols", &top.hide_kernel_symbols,
> > "hide kernel symbols"),
> > + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
> > + parse_vdso_pathnames),
> > OPT_CALLBACK('m', "mmap-pages", &opts->mmap_pages, "pages",
> > "number of mmap data pages", evlist__parse_mmap_pages),
> > OPT_INTEGER('r', "realtime", &top.realtime_prio,
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index 9e5940b5bc59..8d040039a7ce 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -19,6 +19,7 @@
> > #include "build-id.h"
> > #include "cap.h"
> > #include "dso.h"
> > +#include "vdso.h"
> > #include "util.h" // lsdir()
> > #include "debug.h"
> > #include "event.h"
> > @@ -44,6 +45,7 @@
> >
> > static int dso__load_kernel_sym(struct dso *dso, struct map *map);
> > static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
> > +static int dso__load_vdso_sym(struct dso *dso, struct map *map);
> > static bool symbol__is_idle(const char *name);
> >
> > int vmlinux_path__nr_entries;
> > @@ -1833,6 +1835,12 @@ int dso__load(struct dso *dso, struct map *map)
> > goto out;
> > }
> >
> > + if (dso__is_vdso(dso)) {
> > + ret = dso__load_vdso_sym(dso, map);
> > + if (ret > 0)
> > + goto out;
> > + }
> > +
> > dso__set_adjust_symbols(dso, false);
> >
> > if (perfmap) {
> > @@ -2349,6 +2357,72 @@ static int vmlinux_path__init(struct perf_env *env)
> > return -1;
> > }
> >
> > +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
> > + const char *arg, int unset __maybe_unused)
> > +{
> > + char *tmp, *tok, *str = strdup(arg);
> > + unsigned int i = 0;
> > +
> > + for (tok = strtok_r(str, ",", &tmp); tok && i < ARRAY_SIZE(symbol_conf.vdso_name);
> > + tok = strtok_r(NULL, ",", &tmp)) {
> > + symbol_conf.vdso_name[i++] = strdup(tok);
> > + }
> > +
> > + free(str);
> > + return 0;
> > +}
> > +
> > +static int dso__load_vdso(struct dso *dso, struct map *map,
> > + const char *vdso)
> > +{
> > + int err = -1;
> > + struct symsrc ss;
> > + char symfs_vdso[PATH_MAX];
> > +
> > + if (vdso[0] == '/')
> > + snprintf(symfs_vdso, sizeof(symfs_vdso), "%s", vdso);
> > + else
> > + symbol__join_symfs(symfs_vdso, vdso);
> > +
> > + if (symsrc__init(&ss, dso, symfs_vdso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO))
> > + return -1;
> > +
> > + /*
> > + * dso__load_sym() may copy 'dso' which will result in the copies having
> > + * an incorrect long name unless we set it here first.
> > + */
> > + dso__set_long_name(dso, vdso, false);
> > + dso__set_binary_type(dso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO);
> > +
> > + err = dso__load_sym(dso, map, &ss, &ss, 0);
> > + symsrc__destroy(&ss);
> > +
> > + if (err > 0) {
> > + dso__set_loaded(dso);
> > + pr_debug("Using %s for %s symbols\n", symfs_vdso, dso__short_name(dso));
> > + }
> > +
> > + return err;
> > +}
> > +
> > +static int dso__load_vdso_sym(struct dso *dso, struct map *map)
> > +{
> > + int ret;
> > +
> > + if (!dso__is_vdso(dso))
> > + return -1;
> > +
> > + for (unsigned int i = 0; i < ARRAY_SIZE(symbol_conf.vdso_name); i++) {
> > + if (symbol_conf.vdso_name[i] != NULL) {
> > + ret = dso__load_vdso(dso, map, symbol_conf.vdso_name[i]);
> > + if (ret > 0)
> > + return ret;
> > + }
> > + }
> > +
> > + return -1;
> > +}
> > +
> > int setup_list(struct strlist **list, const char *list_str,
> > const char *list_name)
> > {
> > diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
> > index c114bbceef40..108356e3c981 100644
> > --- a/tools/perf/util/symbol_conf.h
> > +++ b/tools/perf/util/symbol_conf.h
> > @@ -3,6 +3,7 @@
> > #define __PERF_SYMBOL_CONF 1
> >
> > #include <stdbool.h>
> > +#include <subcmd/parse-options.h>
> >
> > struct strlist;
> > struct intlist;
> > @@ -55,6 +56,7 @@ struct symbol_conf {
> > const char *default_guest_vmlinux_name,
> > *default_guest_kallsyms,
> > *default_guest_modules;
> > + const char *vdso_name[2];
> > const char *guestmount;
> > const char *dso_list_str,
> > *comm_list_str,
> > @@ -85,4 +87,7 @@ struct symbol_conf {
> >
> > extern struct symbol_conf symbol_conf;
> >
> > +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
> > + const char *arg, int unset __maybe_unused);
> > +
> > #endif // __PERF_SYMBOL_CONF
>
>
--
Cheers,
Changbin Du
On 13/06/24 12:49, duchangbin wrote:
> On Thu, Jun 13, 2024 at 11:23:26AM +0300, Adrian Hunter wrote:
>> On 13/06/24 09:35, Changbin Du wrote:
>>> The vdso dumped from process memory (in buildid-cache) lacks debugging
>>> info. To annotate vdso symbols with source lines we need specify a
>>> debugging version.
>>>
>>> For x86, we can find them from your local build as
>>> arch/x86/entry/vdso/vdso{32,64}.so.dbg. Or they may reside in
>>> /lib/modules/<version>/vdso/vdso{32,64}.so on Ubuntu. But notice that
>>> the buildid has to match.
>>>
>>> $ sudo perf record -a
>>> $ sudo perf report --objdump=llvm-objdump \
>>> --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg
>>>
>>> When doing cross platform analysis, we also need specify the vdso path if
>>> we are interested in its symbols.
>>
>> We already have logic to find debug files, and to deal with a symbol source
>> (syms_ss) and runtime symbol source (runtime_ss).
>>
>> Can't we make that work transparently for vdso so that the user does
>> not have to.
>>
> For Ubuntu, we can find the debug files of vdso in
> /lib/modules/<version>/vdso/vdso{32,64}.so. These two are debug version.
>
> For local build, seems vdso{32,64}.so.dbg are not installed in /lib/modules/ nor
> other locations.
Isn't there /lib/modules/<version>/build symbolic link to follow?
>
>>>
>>> Signed-off-by: Changbin Du <changbin.du@huawei.com>
>>> ---
>>> tools/perf/builtin-annotate.c | 2 +
>>> tools/perf/builtin-c2c.c | 2 +
>>> tools/perf/builtin-inject.c | 2 +
>>> tools/perf/builtin-report.c | 2 +
>>> tools/perf/builtin-script.c | 2 +
>>> tools/perf/builtin-top.c | 2 +
>>> tools/perf/util/symbol.c | 74 +++++++++++++++++++++++++++++++++++
>>> tools/perf/util/symbol_conf.h | 5 +++
>>> 8 files changed, 91 insertions(+)
>>>
>>> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
>>> index 50d2fb222d48..ff466882065d 100644
>>> --- a/tools/perf/builtin-annotate.c
>>> +++ b/tools/perf/builtin-annotate.c
>>> @@ -742,6 +742,8 @@ int cmd_annotate(int argc, const char **argv)
>>> "file", "vmlinux pathname"),
>>> OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
>>> "load module symbols - WARNING: use only with -k and LIVE kernel"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_BOOLEAN('l', "print-line", &annotate_opts.print_lines,
>>> "print matching source lines (may be slow)"),
>>> OPT_BOOLEAN('P', "full-paths", &annotate_opts.full_path,
>>> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
>>> index c157bd31f2e5..4764f9139661 100644
>>> --- a/tools/perf/builtin-c2c.c
>>> +++ b/tools/perf/builtin-c2c.c
>>> @@ -3018,6 +3018,8 @@ static int perf_c2c__report(int argc, const char **argv)
>>> const struct option options[] = {
>>> OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
>>> "file", "vmlinux pathname"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_STRING('i', "input", &input_name, "file",
>>> "the input file to process"),
>>> OPT_INCR('N', "node-info", &c2c.node_info,
>>> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
>>> index a212678d47be..e774e83d0a0f 100644
>>> --- a/tools/perf/builtin-inject.c
>>> +++ b/tools/perf/builtin-inject.c
>>> @@ -2247,6 +2247,8 @@ int cmd_inject(int argc, const char **argv)
>>> "don't load vmlinux even if found"),
>>> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name, "file",
>>> "kallsyms pathname"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_BOOLEAN('f', "force", &data.force, "don't complain, do it"),
>>> OPT_CALLBACK_OPTARG(0, "itrace", &inject.itrace_synth_opts,
>>> NULL, "opts", "Instruction Tracing options\n"
>>> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
>>> index 69618fb0110b..a64b48460dce 100644
>>> --- a/tools/perf/builtin-report.c
>>> +++ b/tools/perf/builtin-report.c
>>> @@ -1324,6 +1324,8 @@ int cmd_report(int argc, const char **argv)
>>> "don't load vmlinux even if found"),
>>> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
>>> "file", "kallsyms pathname"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"),
>>> OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
>>> "load module symbols - WARNING: use only with -k and LIVE kernel"),
>>> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>>> index c16224b1fef3..2e358922a8d1 100644
>>> --- a/tools/perf/builtin-script.c
>>> +++ b/tools/perf/builtin-script.c
>>> @@ -3965,6 +3965,8 @@ int cmd_script(int argc, const char **argv)
>>> "file", "vmlinux pathname"),
>>> OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
>>> "file", "kallsyms pathname"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_BOOLEAN('G', "hide-call-graph", &no_callchain,
>>> "When printing symbols do not display call chain"),
>>> OPT_CALLBACK(0, "symfs", NULL, "directory",
>>> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
>>> index 1d6aef51c122..a3cce4e76eb9 100644
>>> --- a/tools/perf/builtin-top.c
>>> +++ b/tools/perf/builtin-top.c
>>> @@ -1479,6 +1479,8 @@ int cmd_top(int argc, const char **argv)
>>> "file", "kallsyms pathname"),
>>> OPT_BOOLEAN('K', "hide_kernel_symbols", &top.hide_kernel_symbols,
>>> "hide kernel symbols"),
>>> + OPT_CALLBACK(0, "vdso", NULL, "vdso1[,vdso2]", "vdso pathnames",
>>> + parse_vdso_pathnames),
>>> OPT_CALLBACK('m', "mmap-pages", &opts->mmap_pages, "pages",
>>> "number of mmap data pages", evlist__parse_mmap_pages),
>>> OPT_INTEGER('r', "realtime", &top.realtime_prio,
>>> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
>>> index 9e5940b5bc59..8d040039a7ce 100644
>>> --- a/tools/perf/util/symbol.c
>>> +++ b/tools/perf/util/symbol.c
>>> @@ -19,6 +19,7 @@
>>> #include "build-id.h"
>>> #include "cap.h"
>>> #include "dso.h"
>>> +#include "vdso.h"
>>> #include "util.h" // lsdir()
>>> #include "debug.h"
>>> #include "event.h"
>>> @@ -44,6 +45,7 @@
>>>
>>> static int dso__load_kernel_sym(struct dso *dso, struct map *map);
>>> static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
>>> +static int dso__load_vdso_sym(struct dso *dso, struct map *map);
>>> static bool symbol__is_idle(const char *name);
>>>
>>> int vmlinux_path__nr_entries;
>>> @@ -1833,6 +1835,12 @@ int dso__load(struct dso *dso, struct map *map)
>>> goto out;
>>> }
>>>
>>> + if (dso__is_vdso(dso)) {
>>> + ret = dso__load_vdso_sym(dso, map);
>>> + if (ret > 0)
>>> + goto out;
>>> + }
>>> +
>>> dso__set_adjust_symbols(dso, false);
>>>
>>> if (perfmap) {
>>> @@ -2349,6 +2357,72 @@ static int vmlinux_path__init(struct perf_env *env)
>>> return -1;
>>> }
>>>
>>> +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
>>> + const char *arg, int unset __maybe_unused)
>>> +{
>>> + char *tmp, *tok, *str = strdup(arg);
>>> + unsigned int i = 0;
>>> +
>>> + for (tok = strtok_r(str, ",", &tmp); tok && i < ARRAY_SIZE(symbol_conf.vdso_name);
>>> + tok = strtok_r(NULL, ",", &tmp)) {
>>> + symbol_conf.vdso_name[i++] = strdup(tok);
>>> + }
>>> +
>>> + free(str);
>>> + return 0;
>>> +}
>>> +
>>> +static int dso__load_vdso(struct dso *dso, struct map *map,
>>> + const char *vdso)
>>> +{
>>> + int err = -1;
>>> + struct symsrc ss;
>>> + char symfs_vdso[PATH_MAX];
>>> +
>>> + if (vdso[0] == '/')
>>> + snprintf(symfs_vdso, sizeof(symfs_vdso), "%s", vdso);
>>> + else
>>> + symbol__join_symfs(symfs_vdso, vdso);
>>> +
>>> + if (symsrc__init(&ss, dso, symfs_vdso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO))
>>> + return -1;
>>> +
>>> + /*
>>> + * dso__load_sym() may copy 'dso' which will result in the copies having
>>> + * an incorrect long name unless we set it here first.
>>> + */
>>> + dso__set_long_name(dso, vdso, false);
>>> + dso__set_binary_type(dso, DSO_BINARY_TYPE__SYSTEM_PATH_DSO);
>>> +
>>> + err = dso__load_sym(dso, map, &ss, &ss, 0);
>>> + symsrc__destroy(&ss);
>>> +
>>> + if (err > 0) {
>>> + dso__set_loaded(dso);
>>> + pr_debug("Using %s for %s symbols\n", symfs_vdso, dso__short_name(dso));
>>> + }
>>> +
>>> + return err;
>>> +}
>>> +
>>> +static int dso__load_vdso_sym(struct dso *dso, struct map *map)
>>> +{
>>> + int ret;
>>> +
>>> + if (!dso__is_vdso(dso))
>>> + return -1;
>>> +
>>> + for (unsigned int i = 0; i < ARRAY_SIZE(symbol_conf.vdso_name); i++) {
>>> + if (symbol_conf.vdso_name[i] != NULL) {
>>> + ret = dso__load_vdso(dso, map, symbol_conf.vdso_name[i]);
>>> + if (ret > 0)
>>> + return ret;
>>> + }
>>> + }
>>> +
>>> + return -1;
>>> +}
>>> +
>>> int setup_list(struct strlist **list, const char *list_str,
>>> const char *list_name)
>>> {
>>> diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
>>> index c114bbceef40..108356e3c981 100644
>>> --- a/tools/perf/util/symbol_conf.h
>>> +++ b/tools/perf/util/symbol_conf.h
>>> @@ -3,6 +3,7 @@
>>> #define __PERF_SYMBOL_CONF 1
>>>
>>> #include <stdbool.h>
>>> +#include <subcmd/parse-options.h>
>>>
>>> struct strlist;
>>> struct intlist;
>>> @@ -55,6 +56,7 @@ struct symbol_conf {
>>> const char *default_guest_vmlinux_name,
>>> *default_guest_kallsyms,
>>> *default_guest_modules;
>>> + const char *vdso_name[2];
>>> const char *guestmount;
>>> const char *dso_list_str,
>>> *comm_list_str,
>>> @@ -85,4 +87,7 @@ struct symbol_conf {
>>>
>>> extern struct symbol_conf symbol_conf;
>>>
>>> +int parse_vdso_pathnames(const struct option *opt __maybe_unused,
>>> + const char *arg, int unset __maybe_unused);
>>> +
>>> #endif // __PERF_SYMBOL_CONF
>>
>>
>
On Thu, Jun 13, 2024 at 01:19:20PM +0300, Adrian Hunter wrote:
> On 13/06/24 12:49, duchangbin wrote:
> > On Thu, Jun 13, 2024 at 11:23:26AM +0300, Adrian Hunter wrote:
> >> On 13/06/24 09:35, Changbin Du wrote:
> >>> The vdso dumped from process memory (in buildid-cache) lacks debugging
> >>> info. To annotate vdso symbols with source lines we need specify a
> >>> debugging version.
> >>>
> >>> For x86, we can find them from your local build as
> >>> arch/x86/entry/vdso/vdso{32,64}.so.dbg. Or they may reside in
> >>> /lib/modules/<version>/vdso/vdso{32,64}.so on Ubuntu. But notice that
> >>> the buildid has to match.
> >>>
> >>> $ sudo perf record -a
> >>> $ sudo perf report --objdump=llvm-objdump \
> >>> --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg
> >>>
> >>> When doing cross platform analysis, we also need specify the vdso path if
> >>> we are interested in its symbols.
> >>
> >> We already have logic to find debug files, and to deal with a symbol source
> >> (syms_ss) and runtime symbol source (runtime_ss).
> >>
> >> Can't we make that work transparently for vdso so that the user does
> >> not have to.
> >>
> > For Ubuntu, we can find the debug files of vdso in
> > /lib/modules/<version>/vdso/vdso{32,64}.so. These two are debug version.
> >
> > For local build, seems vdso{32,64}.so.dbg are not installed in /lib/modules/ nor
> > other locations.
>
> Isn't there /lib/modules/<version>/build symbolic link to follow?
>
hm, we can try /lib/modules/<version>/build/arch/x86/entry/vdso/vdso*.so.dbg.
Other arches are similar.
So, we will try these pathes internally. And keep '--vdso' if someone really
want a special path. (just like vmlinux)
--
Cheers,
Changbin Du
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