Re: [PATCH v2 1/4] perf: support specify vdso path in cmdline

duchangbin
2024-06-17T06:31:34Z

On Mon, Jun 17, 2024 at 08:26:55AM +0300, Adrian Hunter wrote:
> On 15/06/24 12:20, 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
> >
> > Samples: 17K of event 'cycles:P', 4000 Hz, Event count (approx.): 1760
> > __vdso_clock_gettime /work/linux-host/arch/x86/entry/vdso/vdso64.so.d
> > Percent│ movq -48(%rbp),%rsi
> > │ testq %rax,%rax
> > │ ; return vread_hvclock();
> > │ movq %rax,%rdx
> > │ ; if (unlikely(!vdso_cycles_ok(cycles)))
> > │ ↑ js eb
> > │ ↑ jmp 74
> > │ ; ts->tv_sec = vdso_ts->sec;
> > 0.02 │147: leaq 2(%rbx),%rax
> > │ shlq $4, %rax
> > │ addq %r10,%rax
> > │ ; while ((seq = READ_ONCE(vd->seq)) & 1) {
> > 9.38 │152: movl (%r10),%ecx
> >
> > When doing cross platform analysis, we also need specify the vdso path if
> > we are interested in its symbols.
>
> If perf can now find the vdso debug info, then why is the parameter needed?
>
It's not always available.

For example, I am trying to view result sampled from a arm devices on my x86
host.

> >
> > 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/disasm.c | 5 ++-
> > tools/perf/util/symbol.c | 82 ++++++++++++++++++++++++++++++++++-
> > tools/perf/util/symbol_conf.h | 5 +++
> > 9 files changed, 100 insertions(+), 4 deletions(-)
> >
> > 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/disasm.c b/tools/perf/util/disasm.c
> > index 72aec8f61b94..442e9802a772 100644
> > --- a/tools/perf/util/disasm.c
> > +++ b/tools/perf/util/disasm.c
> > @@ -16,6 +16,7 @@
> > #include "debug.h"
> > #include "disasm.h"
> > #include "dso.h"
> > +#include "vdso.h"
> > #include "env.h"
> > #include "evsel.h"
> > #include "map.h"
> > @@ -1134,7 +1135,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> > goto fallback;
> >
> > linkname[len] = '\0';
> > - if (strstr(linkname, DSO__NAME_KALLSYMS) ||
> > + if (strstr(linkname, DSO__NAME_KALLSYMS) || strstr(linkname, DSO__NAME_VDSO) ||
> > access(filename, R_OK)) {
> > fallback:
> > /*
> > @@ -1142,7 +1143,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> > * cache, or is just a kallsyms file, well, lets hope that this
> > * DSO is the same as when 'perf record' ran.
> > */
> > - if (dso__kernel(dso) && dso__long_name(dso)[0] == '/')
> > + if ((dso__kernel(dso) || dso__is_vdso(dso)) && dso__long_name(dso)[0] == '/')
> > snprintf(filename, filename_size, "%s", dso__long_name(dso));
> > else
> > __symbol__join_symfs(filename, filename_size, dso__long_name(dso));
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index 9e5940b5bc59..a90c647d37e1 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) {
> > @@ -2017,12 +2025,14 @@ int dso__load_vmlinux(struct dso *dso, struct map *map,
> > dso__set_binary_type(dso, DSO_BINARY_TYPE__VMLINUX);
> >
> > err = dso__load_sym(dso, map, &ss, &ss, 0);
> > - symsrc__destroy(&ss);
> > -
> > if (err > 0) {
> > dso__set_loaded(dso);
> > pr_debug("Using %s for symbols\n", symfs_vmlinux);
> > +
> > + if (symsrc__has_symtab(&ss) && !dso__symsrc_filename(dso))
> > + dso__set_symsrc_filename(dso, strdup(symfs_vmlinux));
> > }
> > + symsrc__destroy(&ss);
> >
> > return err;
> > }
> > @@ -2349,6 +2359,74 @@ 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);
> > + if (err > 0) {
> > + dso__set_loaded(dso);
> > + pr_debug("Using %s for %s symbols\n", symfs_vdso, dso__short_name(dso));
> > +
> > + if (symsrc__has_symtab(&ss) && !dso__symsrc_filename(dso))
> > + dso__set_symsrc_filename(dso, strdup(symfs_vdso));
> > + }
> > + symsrc__destroy(&ss);
> > +
> > + 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