Re: [PATCH 1/2] perf: support specify vdso path in cmdline

[Adrian Hunter]

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.

> 
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxxx>
> ---
>  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