[PATCH v6 0/8] perf: Support searching local debugging vdso or specify vdso path in cmdline

[PATCH v6 0/8] perf: Support searching local debugging vdso or specify vdso path in cmdline

[Changbin Du]

The vdso dumped from process memory (in buildid-cache) lacks debugging
info. To annotate vdso symbols with source lines we need 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 resides in
'/lib/modules/<version>/vdso/vdso{32,64}.so' on Ubuntu. But notice that the
builid has to match. 

If user doesn't specify the path, perf will search them internally as long
as vmlinux when recording samples. The searched debugging vdso will add to
buildid cache.

Below samples are captured on my local build kernel. perf succesfully
find debugging version vdso and we can annotate with source without
specifying vdso path.

$ sudo perf record -a
$ sudo perf report --objdump=llvm-objdump

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 need to specify the vdso path if
we are interested in its symbols. At most two vdso can be given. Also you
can pack your buildid cache with perf-archive if the debugging vdso can be
found on the sampled machine.

$ sudo perf report --objdump=llvm-objdump \
      --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg

I also improved perf-buildid-cache command recognize vdso when adding files, then
place it at correct place.

v6:
  - split "perf: build-id: try to search debugging vdso and add to cache" 
    by functional logical. (suggested by Adrian)
v5:
  - Searching the vdso in record stage instead of report. So the debugging
    vdso will be in build-id cache. This is friendly for cross-machine analysis.
  - Improve perf-buildid-cache command recognize vdso when adding files
v4:
  - split the refactoring from the actual change.
v3:
  - update documentation.
v2:
  - now search vdso automatically as long as vmlinux, as suggested by Adrian.
  - remove change 'prefer symsrc_filename for filename'.

Changbin Du (8):
  perf: support specify vdso path in cmdline
  perf: disasm: refactor function dso__disassemble_filename
  perf: disasm: use build_id_path if fallback failed
  perf: symbol: generalize vmlinux path searching
  perf: build-id: add support for build-id cache vdso debug
  perf: build-id: extend build_id_cache__find_debug() to find local
    debugging vdso
  perf: disasm: prefer debugging files in build-id cache
  perf buildid-cache: recognize vdso when adding files

 tools/perf/Documentation/perf-annotate.txt |   3 +
 tools/perf/Documentation/perf-c2c.txt      |   3 +
 tools/perf/Documentation/perf-inject.txt   |   3 +
 tools/perf/Documentation/perf-report.txt   |   3 +
 tools/perf/Documentation/perf-script.txt   |   3 +
 tools/perf/Documentation/perf-top.txt      |   3 +
 tools/perf/builtin-annotate.c              |   2 +
 tools/perf/builtin-buildid-cache.c         |  26 ++-
 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/build-id.c                 |  57 +++++-
 tools/perf/util/disasm.c                   | 131 ++++++++-----
 tools/perf/util/machine.c                  |   4 +-
 tools/perf/util/symbol.c                   | 209 ++++++++++++++++-----
 tools/perf/util/symbol.h                   |   9 +-
 tools/perf/util/symbol_conf.h              |   5 +
 19 files changed, 359 insertions(+), 112 deletions(-)

-- 
2.34.1

[PATCH v6 1/8] perf: support specify vdso path in cmdline

[Changbin Du]

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.

v2: update documentation.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/Documentation/perf-annotate.txt |  3 +
 tools/perf/Documentation/perf-c2c.txt      |  3 +
 tools/perf/Documentation/perf-inject.txt   |  3 +
 tools/perf/Documentation/perf-report.txt   |  3 +
 tools/perf/Documentation/perf-script.txt   |  3 +
 tools/perf/Documentation/perf-top.txt      |  3 +
 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                   |  7 +-
 tools/perf/util/symbol.c                   | 82 +++++++++++++++++++++-
 tools/perf/util/symbol_conf.h              |  5 ++
 15 files changed, 119 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
index b95524bea021..4b6692f9a793 100644
--- a/tools/perf/Documentation/perf-annotate.txt
+++ b/tools/perf/Documentation/perf-annotate.txt
@@ -58,6 +58,9 @@ OPTIONS
 --ignore-vmlinux::
 	Ignore vmlinux files.
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 --itrace::
 	Options for decoding instruction tracing data. The options are:
 
diff --git a/tools/perf/Documentation/perf-c2c.txt b/tools/perf/Documentation/perf-c2c.txt
index 856f0dfb8e5a..7c07efca7542 100644
--- a/tools/perf/Documentation/perf-c2c.txt
+++ b/tools/perf/Documentation/perf-c2c.txt
@@ -71,6 +71,9 @@ REPORT OPTIONS
 --vmlinux=<file>::
 	vmlinux pathname
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 -v::
 --verbose::
 	Be more verbose (show counter open errors, etc).
diff --git a/tools/perf/Documentation/perf-inject.txt b/tools/perf/Documentation/perf-inject.txt
index c972032f4ca0..3c88967b4c7f 100644
--- a/tools/perf/Documentation/perf-inject.txt
+++ b/tools/perf/Documentation/perf-inject.txt
@@ -62,6 +62,9 @@ OPTIONS
 --kallsyms=<file>::
 	kallsyms pathname
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 --itrace::
 	Decode Instruction Tracing data, replacing it with synthesized events.
 	Options are:
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index d2b1593ef700..8a3ba5f74cac 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -345,6 +345,9 @@ OPTIONS
         Load module symbols. WARNING: This should only be used with -k and
         a LIVE kernel.
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 -f::
 --force::
         Don't do ownership validation.
diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index ff086ef05a0c..48f9974ca4c5 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -296,6 +296,9 @@ OPTIONS
 --kallsyms=<file>::
         kallsyms pathname
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 --symfs=<directory>::
         Look for files with symbols relative to this directory.
 
diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index 667e5102075e..99f53b5b336b 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -80,6 +80,9 @@ Default is to monitor all CPUS.
 --kallsyms=<file>::
 	kallsyms pathname
 
+--vdso=<vdso1[,vdso2]>::
+	Specify vdso pathnames. You can specify up to two for multiarch-support.
+
 -m <pages>::
 --mmap-pages=<pages>::
 	Number of mmap data pages (must be a power of two) or size
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index b10b7f005658..e0aa657e6ca0 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 6edc0d4ce6fb..00ddf4f06324 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -1321,6 +1321,8 @@ 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 e8cbbf10d361..3a4cee6f2d2f 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1488,6 +1488,8 @@ 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 e10558b79504..7e26d5215640 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"
@@ -1126,7 +1127,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 	if (pos && strlen(pos) < SBUILD_ID_SIZE - 2)
 		dirname(build_id_path);
 
-	if (dso__is_kcore(dso))
+	if (dso__is_kcore(dso) || dso__is_vdso(dso))
 		goto fallback;
 
 	len = readlink(build_id_path, linkname, sizeof(linkname) - 1);
@@ -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 19eb623e0826..ad3b7b929e94 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;
@@ -1832,6 +1834,12 @@ 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) {
@@ -2016,12 +2024,14 @@ 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;
 }
@@ -2348,6 +2358,74 @@ 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 657cfa5af43c..deaec9a60904 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;
@@ -56,6 +57,7 @@ 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,
@@ -86,4 +88,7 @@ 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
-- 
2.34.1

Re: [PATCH v6 1/8] perf: support specify vdso path in cmdline

[Adrian Hunter]

On 25/07/24 05:15, 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.
> 
> v2: update documentation.
> 
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> ---
>  tools/perf/Documentation/perf-annotate.txt |  3 +
>  tools/perf/Documentation/perf-c2c.txt      |  3 +
>  tools/perf/Documentation/perf-inject.txt   |  3 +
>  tools/perf/Documentation/perf-report.txt   |  3 +
>  tools/perf/Documentation/perf-script.txt   |  3 +
>  tools/perf/Documentation/perf-top.txt      |  3 +
>  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                   |  7 +-
>  tools/perf/util/symbol.c                   | 82 +++++++++++++++++++++-
>  tools/perf/util/symbol_conf.h              |  5 ++
>  15 files changed, 119 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
> index b95524bea021..4b6692f9a793 100644
> --- a/tools/perf/Documentation/perf-annotate.txt
> +++ b/tools/perf/Documentation/perf-annotate.txt
> @@ -58,6 +58,9 @@ OPTIONS
>  --ignore-vmlinux::
>  	Ignore vmlinux files.
>  
> +--vdso=<vdso1[,vdso2]>::
> +	Specify vdso pathnames. You can specify up to two for multiarch-support.
> +
>  --itrace::
>  	Options for decoding instruction tracing data. The options are:
>  

<SNIP>

> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> index b10b7f005658..e0aa657e6ca0 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,

<SNIP>

> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> index e10558b79504..7e26d5215640 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"
> @@ -1126,7 +1127,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
>  	if (pos && strlen(pos) < SBUILD_ID_SIZE - 2)
>  		dirname(build_id_path);
>  
> -	if (dso__is_kcore(dso))
> +	if (dso__is_kcore(dso) || dso__is_vdso(dso))

Sorry for very long delay.

This patch (probably this bit here) breaks annotation of vdso.
To allow for bisection, you need to arrange changes so that each
patch leaves things in a working state.

However, I disagree with adding --vdso option since with just
patch 8 alone, it would be possible to do:

  perf buildid-cache --remove /work/linux/arch/x86/entry/vdso/vdso64.so.dbg
  perf buildid-cache --add /work/linux/arch/x86/entry/vdso/vdso64.so.dbg

and same of vdso32.

That would leave the buildid-cache containing only the debug versions,
which would mean you will only get the debug versions, and it would only
need to be done once per kernel instead of having to add --vdso to
every perf command.

Re: [PATCH v6 1/8] perf: support specify vdso path in cmdline

[duchangbin]

Hi, Adrian,

On Wed, Sep 11, 2024 at 11:03:21AM +0300, Adrian Hunter wrote:
> On 25/07/24 05:15, 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.
> > 
> > v2: update documentation.
> > 
> > Signed-off-by: Changbin Du <changbin.du@huawei.com>
> > ---
> >  tools/perf/Documentation/perf-annotate.txt |  3 +
> >  tools/perf/Documentation/perf-c2c.txt      |  3 +
> >  tools/perf/Documentation/perf-inject.txt   |  3 +
> >  tools/perf/Documentation/perf-report.txt   |  3 +
> >  tools/perf/Documentation/perf-script.txt   |  3 +
> >  tools/perf/Documentation/perf-top.txt      |  3 +
> >  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                   |  7 +-
> >  tools/perf/util/symbol.c                   | 82 +++++++++++++++++++++-
> >  tools/perf/util/symbol_conf.h              |  5 ++
> >  15 files changed, 119 insertions(+), 5 deletions(-)
> > 
> > diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
> > index b95524bea021..4b6692f9a793 100644
> > --- a/tools/perf/Documentation/perf-annotate.txt
> > +++ b/tools/perf/Documentation/perf-annotate.txt
> > @@ -58,6 +58,9 @@ OPTIONS
> >  --ignore-vmlinux::
> >  	Ignore vmlinux files.
> >  
> > +--vdso=<vdso1[,vdso2]>::
> > +	Specify vdso pathnames. You can specify up to two for multiarch-support.
> > +
> >  --itrace::
> >  	Options for decoding instruction tracing data. The options are:
> >  
> 
> <SNIP>
> 
> > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> > index b10b7f005658..e0aa657e6ca0 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,
> 
> <SNIP>
> 
> > diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> > index e10558b79504..7e26d5215640 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"
> > @@ -1126,7 +1127,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
> >  	if (pos && strlen(pos) < SBUILD_ID_SIZE - 2)
> >  		dirname(build_id_path);
> >  
> > -	if (dso__is_kcore(dso))
> > +	if (dso__is_kcore(dso) || dso__is_vdso(dso))
> 
> Sorry for very long delay.
> 
> This patch (probably this bit here) breaks annotation of vdso.
> To allow for bisection, you need to arrange changes so that each
> patch leaves things in a working state.
> 
> However, I disagree with adding --vdso option since with just
> patch 8 alone, it would be possible to do:
> 
>   perf buildid-cache --remove /work/linux/arch/x86/entry/vdso/vdso64.so.dbg
>   perf buildid-cache --add /work/linux/arch/x86/entry/vdso/vdso64.so.dbg
> 
> and same of vdso32.
> 
> That would leave the buildid-cache containing only the debug versions,
> which would mean you will only get the debug versions, and it would only
> need to be done once per kernel instead of having to add --vdso to
> every perf command.
>

I may send patch 8 alone first and suspend the rest. I suppose mananging buildid-cache
for vdso mannually is enough for most case. So maybe it's better not get things
more complex.

> 

-- 
Cheers,
Changbin Du

[PATCH v6 2/8] perf: disasm: refactor function dso__disassemble_filename

[Changbin Du]

To make change easy, this change refactors the dso__disassemble_filename()
function by extracting two functions read_buildid_linkname() and
fallback_filename().

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

---
v2: split refactoring from logical change.
---
 tools/perf/util/disasm.c | 117 +++++++++++++++++++++++----------------
 1 file changed, 70 insertions(+), 47 deletions(-)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 7e26d5215640..0ece6e06da6f 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1092,28 +1092,12 @@ int symbol__strerror_disassemble(struct map_symbol *ms, int errnum, char *buf, s
 	return 0;
 }
 
-static int dso__disassemble_filename(struct dso *dso, char *filename, size_t filename_size)
+static int read_buildid_linkname(char *filename, char *linkname, size_t linkname_size)
 {
-	char linkname[PATH_MAX];
-	char *build_id_filename;
 	char *build_id_path = NULL;
 	char *pos;
 	int len;
 
-	if (dso__symtab_type(dso) == DSO_BINARY_TYPE__KALLSYMS &&
-	    !dso__is_kcore(dso))
-		return SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
-
-	build_id_filename = dso__build_id_filename(dso, NULL, 0, false);
-	if (build_id_filename) {
-		__symbol__join_symfs(filename, filename_size, build_id_filename);
-		free(build_id_filename);
-	} else {
-		if (dso__has_build_id(dso))
-			return ENOMEM;
-		goto fallback;
-	}
-
 	build_id_path = strdup(filename);
 	if (!build_id_path)
 		return ENOMEM;
@@ -1127,41 +1111,80 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 	if (pos && strlen(pos) < SBUILD_ID_SIZE - 2)
 		dirname(build_id_path);
 
-	if (dso__is_kcore(dso) || dso__is_vdso(dso))
-		goto fallback;
-
-	len = readlink(build_id_path, linkname, sizeof(linkname) - 1);
-	if (len < 0)
-		goto fallback;
+	len = readlink(build_id_path, linkname, linkname_size);
+	if (len < 0) {
+		free(build_id_path);
+		return -1;
+	}
 
 	linkname[len] = '\0';
-	if (strstr(linkname, DSO__NAME_KALLSYMS) || strstr(linkname, DSO__NAME_VDSO) ||
-		access(filename, R_OK)) {
-fallback:
-		/*
-		 * If we don't have build-ids or the build-id file isn't in the
-		 * 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__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));
-
-		mutex_lock(dso__lock(dso));
-		if (access(filename, R_OK) && errno == ENOENT && dso__nsinfo(dso)) {
-			char *new_name = dso__filename_with_chroot(dso, filename);
-			if (new_name) {
-				strlcpy(filename, new_name, filename_size);
-				free(new_name);
-			}
+	free(build_id_path);
+	return 0;
+}
+
+static int fallback_filename(struct dso *dso, char *filename, size_t filename_size)
+{
+	char filepath[PATH_MAX];
+
+	/*
+	 * If we don't have build-ids or the build-id file isn't in the
+	 * 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__is_vdso(dso)) && dso__long_name(dso)[0] == '/')
+		snprintf(filepath, sizeof(filepath), "%s", dso__long_name(dso));
+	else
+		__symbol__join_symfs(filepath, sizeof(filepath), dso__long_name(dso));
+
+	mutex_lock(dso__lock(dso));
+	if (access(filepath, R_OK) && errno == ENOENT && dso__nsinfo(dso)) {
+		char *new_name = dso__filename_with_chroot(dso, filepath);
+		if (new_name) {
+			strlcpy(filepath, new_name, sizeof(filepath));
+			free(new_name);
 		}
-		mutex_unlock(dso__lock(dso));
-	} else if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND) {
-		dso__set_binary_type(dso, DSO_BINARY_TYPE__BUILD_ID_CACHE);
 	}
+	mutex_unlock(dso__lock(dso));
 
-	free(build_id_path);
+	if (access(filepath, R_OK) && errno == ENOENT)
+		return ENOENT;
+
+	snprintf(filename, filename_size, "%s", filepath);
+	return 0;
+}
+
+static int dso__disassemble_filename(struct dso *dso, char *filename, size_t filename_size)
+{
+	char linkname[PATH_MAX];
+	char *build_id_filename;
+
+	if (dso__symtab_type(dso) == DSO_BINARY_TYPE__KALLSYMS &&
+	    !dso__is_kcore(dso))
+		return SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
+
+	build_id_filename = dso__build_id_filename(dso, NULL, 0, false);
+	if (build_id_filename) {
+		__symbol__join_symfs(filename, filename_size, build_id_filename);
+		free(build_id_filename);
+	} else {
+		if (dso__has_build_id(dso))
+			return ENOMEM;
+		return fallback_filename(dso, filename, filename_size);
+	}
+
+	if (access(filename, R_OK))
+		return fallback_filename(dso, filename, filename_size);
+
+	if (dso__is_kcore(dso) || dso__is_vdso(dso))
+		return fallback_filename(dso, filename, filename_size);
+
+	if (read_buildid_linkname(filename, linkname, sizeof(linkname) - 1) ||
+	    strstr(linkname, DSO__NAME_KALLSYMS) || strstr(linkname, DSO__NAME_VDSO)) {
+		return fallback_filename(dso, filename, filename_size);
+	}
+
+	if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND)
+		dso__set_binary_type(dso, DSO_BINARY_TYPE__BUILD_ID_CACHE);
 	return 0;
 }
 
-- 
2.34.1

[PATCH v6 3/8] perf: disasm: use build_id_path if fallback failed

[Changbin Du]

If we can not fallback for special dso (vmlinx and vdso), use the
build_id_path found previously.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/util/disasm.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 0ece6e06da6f..6af9fbec3a95 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1176,15 +1176,21 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 		return fallback_filename(dso, filename, filename_size);
 
 	if (dso__is_kcore(dso) || dso__is_vdso(dso))
-		return fallback_filename(dso, filename, filename_size);
+		goto fallback;
 
-	if (read_buildid_linkname(filename, linkname, sizeof(linkname) - 1) ||
-	    strstr(linkname, DSO__NAME_KALLSYMS) || strstr(linkname, DSO__NAME_VDSO)) {
-		return fallback_filename(dso, filename, filename_size);
+	if (!read_buildid_linkname(filename, linkname, sizeof(linkname) - 1) &&
+	    (!strstr(linkname, DSO__NAME_KALLSYMS) && !strstr(linkname, DSO__NAME_VDSO))) {
+		/* It's not kallsysms or vdso, use build_id path found above */
+		goto out;
 	}
 
-	if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND)
-		dso__set_binary_type(dso, DSO_BINARY_TYPE__BUILD_ID_CACHE);
+fallback:
+	if (fallback_filename(dso, filename, filename_size)) {
+		/* if fallback failed, use build_id path found above */
+out:
+		if (dso__binary_type(dso) == DSO_BINARY_TYPE__NOT_FOUND)
+			dso__set_binary_type(dso, DSO_BINARY_TYPE__BUILD_ID_CACHE);
+	}
 	return 0;
 }
 
-- 
2.34.1

[PATCH v6 4/8] perf: symbol: generalize vmlinux path searching

[Changbin Du]

This generalizes the vmlinux path searching logic. Later we will add
another instance for vdso.

The search pattern is described by struct dso_filename_pattern, and the
formatted paths are hold in struct dso_filename_paths.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/util/machine.c |   4 +-
 tools/perf/util/symbol.c  | 112 +++++++++++++++++++++-----------------
 tools/perf/util/symbol.h  |   8 ++-
 3 files changed, 70 insertions(+), 54 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 8477edefc299..68315520f15b 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -896,9 +896,9 @@ size_t machine__fprintf_vmlinux_path(struct machine *machine, FILE *fp)
 			printed += fprintf(fp, "[0] %s\n", filename);
 	}
 
-	for (i = 0; i < vmlinux_path__nr_entries; ++i) {
+	for (i = 0; i < vmlinux_paths.nr_entries; ++i) {
 		printed += fprintf(fp, "[%d] %s\n", i + dso__has_build_id(kdso),
-				   vmlinux_path[i]);
+				   vmlinux_paths.paths[i]);
 	}
 	return printed;
 }
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index ad3b7b929e94..6bf75c98e1f2 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -48,8 +48,7 @@ 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;
-char **vmlinux_path;
+struct dso_filename_paths vmlinux_paths;
 
 struct symbol_conf symbol_conf = {
 	.nanosecs		= false,
@@ -2042,10 +2041,10 @@ int dso__load_vmlinux_path(struct dso *dso, struct map *map)
 	char *filename = NULL;
 
 	pr_debug("Looking at the vmlinux_path (%d entries long)\n",
-		 vmlinux_path__nr_entries + 1);
+		 vmlinux_paths.nr_entries + 1);
 
-	for (i = 0; i < vmlinux_path__nr_entries; ++i) {
-		err = dso__load_vmlinux(dso, map, vmlinux_path[i], false);
+	for (i = 0; i < vmlinux_paths.nr_entries; ++i) {
+		err = dso__load_vmlinux(dso, map, vmlinux_paths.paths[i], false);
 		if (err > 0)
 			goto out;
 	}
@@ -2209,7 +2208,7 @@ static int dso__load_kernel_sym(struct dso *dso, struct map *map)
 			return err;
 	}
 
-	if (!symbol_conf.ignore_vmlinux && vmlinux_path != NULL) {
+	if (!symbol_conf.ignore_vmlinux && vmlinux_paths.paths != NULL) {
 		err = dso__load_vmlinux_path(dso, map);
 		if (err > 0)
 			return err;
@@ -2284,57 +2283,55 @@ static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map)
 	return err;
 }
 
-static void vmlinux_path__exit(void)
-{
-	while (--vmlinux_path__nr_entries >= 0)
-		zfree(&vmlinux_path[vmlinux_path__nr_entries]);
-	vmlinux_path__nr_entries = 0;
-
-	zfree(&vmlinux_path);
-}
-
-static const char * const vmlinux_paths[] = {
-	"vmlinux",
-	"/boot/vmlinux"
+struct dso_filename_pattern {
+	const char *pattern;
+	/*
+	 * 0 for matching directly,
+	 * 1 for matching by kernel_version,
+	 * 2 for matching by kernel_version + arch.
+	 */
+	int match_type;
 };
 
-static const char * const vmlinux_paths_upd[] = {
-	"/boot/vmlinux-%s",
-	"/usr/lib/debug/boot/vmlinux-%s",
-	"/lib/modules/%s/build/vmlinux",
-	"/usr/lib/debug/lib/modules/%s/vmlinux",
-	"/usr/lib/debug/boot/vmlinux-%s.debug"
+struct dso_filename_pattern vmlinux_patterns[] = {
+	{"vmlinux", 0},
+	{"/boot/vmlinux", 0},
+	{"/boot/vmlinux-%s", 1},
+	{"/usr/lib/debug/boot/vmlinux-%s", 1},
+	{"/lib/modules/%s/build/vmlinux", 1},
+	{"/usr/lib/debug/lib/modules/%s/vmlinux", 1},
+	{"/usr/lib/debug/boot/vmlinux-%s.debug", 1},
 };
 
-static int vmlinux_path__add(const char *new_entry)
+static int dso_filename_path__add(struct dso_filename_paths *paths, const char *new_entry)
 {
-	vmlinux_path[vmlinux_path__nr_entries] = strdup(new_entry);
-	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
+	paths->paths[paths->nr_entries] = strdup(new_entry);
+	if (paths->paths[paths->nr_entries] == NULL)
 		return -1;
-	++vmlinux_path__nr_entries;
+	++paths->nr_entries;
 
 	return 0;
 }
 
-static int vmlinux_path__init(struct perf_env *env)
+static void dso_filename_path__exit(struct dso_filename_paths *paths)
 {
-	struct utsname uts;
-	char bf[PATH_MAX];
-	char *kernel_version;
-	unsigned int i;
+	while (--paths->nr_entries >= 0)
+		zfree(&paths->paths[paths->nr_entries]);
+	paths->nr_entries = 0;
 
-	vmlinux_path = malloc(sizeof(char *) * (ARRAY_SIZE(vmlinux_paths) +
-			      ARRAY_SIZE(vmlinux_paths_upd)));
-	if (vmlinux_path == NULL)
-		return -1;
-
-	for (i = 0; i < ARRAY_SIZE(vmlinux_paths); i++)
-		if (vmlinux_path__add(vmlinux_paths[i]) < 0)
-			goto out_fail;
+	zfree(&paths->paths);
+}
 
-	/* only try kernel version if no symfs was given */
-	if (symbol_conf.symfs[0] != 0)
-		return 0;
+static int dso_filename_path__init(struct dso_filename_paths *paths,
+				   struct dso_filename_pattern *patterns,
+				   int nr_patterns,
+				   struct perf_env *env)
+{
+	struct utsname uts;
+	char bf[PATH_MAX];
+	const char *kernel_version;
+	const char *arch = perf_env__arch(env);
+	int i;
 
 	if (env) {
 		kernel_version = env->os_release;
@@ -2345,16 +2342,28 @@ static int vmlinux_path__init(struct perf_env *env)
 		kernel_version = uts.release;
 	}
 
-	for (i = 0; i < ARRAY_SIZE(vmlinux_paths_upd); i++) {
-		snprintf(bf, sizeof(bf), vmlinux_paths_upd[i], kernel_version);
-		if (vmlinux_path__add(bf) < 0)
+	paths->paths = malloc(sizeof(char *) * nr_patterns);
+	if (paths->paths == NULL)
+		return -1;
+
+	for (i = 0; i < nr_patterns; i++) {
+		if (patterns[i].match_type == 0)
+			strlcpy(bf, patterns[i].pattern, sizeof(bf));
+		else if (symbol_conf.symfs[0] == 0) {
+			/* only try kernel version if no symfs was given */
+			if (patterns[i].match_type == 1)
+				snprintf(bf, sizeof(bf), patterns[i].pattern, kernel_version);
+			else if (patterns[i].match_type == 2)
+				snprintf(bf, sizeof(bf), patterns[i].pattern, kernel_version, arch);
+		}
+		if (dso_filename_path__add(paths, bf) < 0)
 			goto out_fail;
 	}
 
 	return 0;
 
 out_fail:
-	vmlinux_path__exit();
+	dso_filename_path__exit(paths);
 	return -1;
 }
 
@@ -2550,8 +2559,11 @@ int symbol__init(struct perf_env *env)
 
 	symbol__elf_init();
 
-	if (symbol_conf.try_vmlinux_path && vmlinux_path__init(env) < 0)
+	if (symbol_conf.try_vmlinux_path &&
+	    dso_filename_path__init(&vmlinux_paths, vmlinux_patterns,
+				    ARRAY_SIZE(vmlinux_patterns), env) < 0) {
 		return -1;
+	}
 
 	if (symbol_conf.field_sep && *symbol_conf.field_sep == '.') {
 		pr_err("'.' is the only non valid --field-separator argument\n");
@@ -2628,7 +2640,7 @@ void symbol__exit(void)
 	intlist__delete(symbol_conf.tid_list);
 	intlist__delete(symbol_conf.pid_list);
 	intlist__delete(symbol_conf.addr_list);
-	vmlinux_path__exit();
+	dso_filename_path__exit(&vmlinux_paths);
 	symbol_conf.sym_list = symbol_conf.dso_list = symbol_conf.comm_list = NULL;
 	symbol_conf.bt_stop_list = NULL;
 	symbol_conf.initialized = false;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 3fb5d146d9b1..30056884945b 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -101,8 +101,12 @@ static inline int __symbol__join_symfs(char *bf, size_t size, const char *path)
 
 #define symbol__join_symfs(bf, path) __symbol__join_symfs(bf, sizeof(bf), path)
 
-extern int vmlinux_path__nr_entries;
-extern char **vmlinux_path;
+struct dso_filename_paths {
+	int nr_entries;
+	char **paths;
+};
+
+extern struct dso_filename_paths vmlinux_paths;
 
 static inline void *symbol__priv(struct symbol *sym)
 {
-- 
2.34.1

Re: [PATCH v6 4/8] perf: symbol: generalize vmlinux path searching

[Adrian Hunter]

On 25/07/24 05:15, Changbin Du wrote:
> This generalizes the vmlinux path searching logic. Later we will add
> another instance for vdso.
> 
> The search pattern is described by struct dso_filename_pattern, and the
> formatted paths are hold in struct dso_filename_paths.
> 
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> ---
>  tools/perf/util/machine.c |   4 +-
>  tools/perf/util/symbol.c  | 112 +++++++++++++++++++++-----------------
>  tools/perf/util/symbol.h  |   8 ++-
>  3 files changed, 70 insertions(+), 54 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 8477edefc299..68315520f15b 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -896,9 +896,9 @@ size_t machine__fprintf_vmlinux_path(struct machine *machine, FILE *fp)
>  			printed += fprintf(fp, "[0] %s\n", filename);
>  	}
>  
> -	for (i = 0; i < vmlinux_path__nr_entries; ++i) {
> +	for (i = 0; i < vmlinux_paths.nr_entries; ++i) {
>  		printed += fprintf(fp, "[%d] %s\n", i + dso__has_build_id(kdso),
> -				   vmlinux_path[i]);
> +				   vmlinux_paths.paths[i]);
>  	}
>  	return printed;
>  }
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index ad3b7b929e94..6bf75c98e1f2 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -48,8 +48,7 @@ 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;
> -char **vmlinux_path;
> +struct dso_filename_paths vmlinux_paths;
>  
>  struct symbol_conf symbol_conf = {
>  	.nanosecs		= false,
> @@ -2042,10 +2041,10 @@ int dso__load_vmlinux_path(struct dso *dso, struct map *map)
>  	char *filename = NULL;
>  
>  	pr_debug("Looking at the vmlinux_path (%d entries long)\n",
> -		 vmlinux_path__nr_entries + 1);
> +		 vmlinux_paths.nr_entries + 1);
>  
> -	for (i = 0; i < vmlinux_path__nr_entries; ++i) {
> -		err = dso__load_vmlinux(dso, map, vmlinux_path[i], false);
> +	for (i = 0; i < vmlinux_paths.nr_entries; ++i) {
> +		err = dso__load_vmlinux(dso, map, vmlinux_paths.paths[i], false);
>  		if (err > 0)
>  			goto out;
>  	}
> @@ -2209,7 +2208,7 @@ static int dso__load_kernel_sym(struct dso *dso, struct map *map)
>  			return err;
>  	}
>  
> -	if (!symbol_conf.ignore_vmlinux && vmlinux_path != NULL) {
> +	if (!symbol_conf.ignore_vmlinux && vmlinux_paths.paths != NULL) {
>  		err = dso__load_vmlinux_path(dso, map);
>  		if (err > 0)
>  			return err;
> @@ -2284,57 +2283,55 @@ static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map)
>  	return err;
>  }
>  
> -static void vmlinux_path__exit(void)
> -{
> -	while (--vmlinux_path__nr_entries >= 0)
> -		zfree(&vmlinux_path[vmlinux_path__nr_entries]);
> -	vmlinux_path__nr_entries = 0;
> -
> -	zfree(&vmlinux_path);
> -}
> -
> -static const char * const vmlinux_paths[] = {
> -	"vmlinux",
> -	"/boot/vmlinux"
> +struct dso_filename_pattern {
> +	const char *pattern;
> +	/*
> +	 * 0 for matching directly,
> +	 * 1 for matching by kernel_version,
> +	 * 2 for matching by kernel_version + arch.
> +	 */
> +	int match_type;
>  };
>  
> -static const char * const vmlinux_paths_upd[] = {
> -	"/boot/vmlinux-%s",
> -	"/usr/lib/debug/boot/vmlinux-%s",
> -	"/lib/modules/%s/build/vmlinux",
> -	"/usr/lib/debug/lib/modules/%s/vmlinux",
> -	"/usr/lib/debug/boot/vmlinux-%s.debug"
> +struct dso_filename_pattern vmlinux_patterns[] = {
> +	{"vmlinux", 0},
> +	{"/boot/vmlinux", 0},
> +	{"/boot/vmlinux-%s", 1},
> +	{"/usr/lib/debug/boot/vmlinux-%s", 1},
> +	{"/lib/modules/%s/build/vmlinux", 1},
> +	{"/usr/lib/debug/lib/modules/%s/vmlinux", 1},
> +	{"/usr/lib/debug/boot/vmlinux-%s.debug", 1},
>  };
>  
> -static int vmlinux_path__add(const char *new_entry)
> +static int dso_filename_path__add(struct dso_filename_paths *paths, const char *new_entry)
>  {
> -	vmlinux_path[vmlinux_path__nr_entries] = strdup(new_entry);
> -	if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
> +	paths->paths[paths->nr_entries] = strdup(new_entry);
> +	if (paths->paths[paths->nr_entries] == NULL)
>  		return -1;
> -	++vmlinux_path__nr_entries;
> +	++paths->nr_entries;
>  
>  	return 0;
>  }
>  
> -static int vmlinux_path__init(struct perf_env *env)
> +static void dso_filename_path__exit(struct dso_filename_paths *paths)
>  {
> -	struct utsname uts;
> -	char bf[PATH_MAX];
> -	char *kernel_version;
> -	unsigned int i;
> +	while (--paths->nr_entries >= 0)
> +		zfree(&paths->paths[paths->nr_entries]);
> +	paths->nr_entries = 0;
>  
> -	vmlinux_path = malloc(sizeof(char *) * (ARRAY_SIZE(vmlinux_paths) +
> -			      ARRAY_SIZE(vmlinux_paths_upd)));
> -	if (vmlinux_path == NULL)
> -		return -1;
> -
> -	for (i = 0; i < ARRAY_SIZE(vmlinux_paths); i++)
> -		if (vmlinux_path__add(vmlinux_paths[i]) < 0)
> -			goto out_fail;
> +	zfree(&paths->paths);
> +}
>  
> -	/* only try kernel version if no symfs was given */
> -	if (symbol_conf.symfs[0] != 0)
> -		return 0;
> +static int dso_filename_path__init(struct dso_filename_paths *paths,
> +				   struct dso_filename_pattern *patterns,
> +				   int nr_patterns,
> +				   struct perf_env *env)
> +{
> +	struct utsname uts;
> +	char bf[PATH_MAX];
> +	const char *kernel_version;
> +	const char *arch = perf_env__arch(env);
> +	int i;
>  
>  	if (env) {
>  		kernel_version = env->os_release;
> @@ -2345,16 +2342,28 @@ static int vmlinux_path__init(struct perf_env *env)
>  		kernel_version = uts.release;
>  	}
>  
> -	for (i = 0; i < ARRAY_SIZE(vmlinux_paths_upd); i++) {
> -		snprintf(bf, sizeof(bf), vmlinux_paths_upd[i], kernel_version);
> -		if (vmlinux_path__add(bf) < 0)
> +	paths->paths = malloc(sizeof(char *) * nr_patterns);
> +	if (paths->paths == NULL)
> +		return -1;
> +
> +	for (i = 0; i < nr_patterns; i++) {
> +		if (patterns[i].match_type == 0)
> +			strlcpy(bf, patterns[i].pattern, sizeof(bf));
> +		else if (symbol_conf.symfs[0] == 0) {
> +			/* only try kernel version if no symfs was given */
> +			if (patterns[i].match_type == 1)
> +				snprintf(bf, sizeof(bf), patterns[i].pattern, kernel_version);
> +			else if (patterns[i].match_type == 2)
> +				snprintf(bf, sizeof(bf), patterns[i].pattern, kernel_version, arch);
> +		}
> +		if (dso_filename_path__add(paths, bf) < 0)
>  			goto out_fail;
>  	}
>  
>  	return 0;
>  
>  out_fail:
> -	vmlinux_path__exit();
> +	dso_filename_path__exit(paths);
>  	return -1;
>  }
>  
> @@ -2550,8 +2559,11 @@ int symbol__init(struct perf_env *env)
>  
>  	symbol__elf_init();
>  
> -	if (symbol_conf.try_vmlinux_path && vmlinux_path__init(env) < 0)
> +	if (symbol_conf.try_vmlinux_path &&
> +	    dso_filename_path__init(&vmlinux_paths, vmlinux_patterns,
> +				    ARRAY_SIZE(vmlinux_patterns), env) < 0) {
>  		return -1;
> +	}
>  
>  	if (symbol_conf.field_sep && *symbol_conf.field_sep == '.') {
>  		pr_err("'.' is the only non valid --field-separator argument\n");
> @@ -2628,7 +2640,7 @@ void symbol__exit(void)
>  	intlist__delete(symbol_conf.tid_list);
>  	intlist__delete(symbol_conf.pid_list);
>  	intlist__delete(symbol_conf.addr_list);
> -	vmlinux_path__exit();
> +	dso_filename_path__exit(&vmlinux_paths);
>  	symbol_conf.sym_list = symbol_conf.dso_list = symbol_conf.comm_list = NULL;
>  	symbol_conf.bt_stop_list = NULL;
>  	symbol_conf.initialized = false;
> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> index 3fb5d146d9b1..30056884945b 100644
> --- a/tools/perf/util/symbol.h
> +++ b/tools/perf/util/symbol.h
> @@ -101,8 +101,12 @@ static inline int __symbol__join_symfs(char *bf, size_t size, const char *path)
>  
>  #define symbol__join_symfs(bf, path) __symbol__join_symfs(bf, sizeof(bf), path)
>  
> -extern int vmlinux_path__nr_entries;
> -extern char **vmlinux_path;
> +struct dso_filename_paths {
> +	int nr_entries;
> +	char **paths;
> +};

Feels a bit over engineered.  We only need the nth path so
a simpler, more encapsulated API could be just:

const char *vdso_path(size_t i);

Also wonder why the paths cannot just be created by asprint().
e.g. notwithstanding that perf_env__os_release() does not exist:


#define MAX_VDSO_PATHS 8
static char *vdso_paths[MAX_VDSO_PATHS];
static size_t vdso_path__nr_entries;

static int vdso_path__init(struct perf_env *env)
{
	const char *k = perf_env__os_release(env);
	const char *a = perf_env__arch(env);
	int i = 0;

#define PATH_INIT(fmt, ...)						\
	(i < MAX_VDSO_PATHS ? ({					\
		int ret = asprintf(&vdso_paths[i], fmt, ##__VA_ARGS__);	\
		if (ret >= 0) {						\
			i += 1;						\
			ret = 0;					\
		}							\
		ret;							\
	}) : -1)

	if (PATH_INIT("/lib/modules/%s/vdso/vdso.so", k) ||
	    PATH_INIT("/lib/modules/%s/vdso/vdso64.so", k) ||
	    PATH_INIT("/lib/modules/%s/vdso/vdso32.so", k) ||
	    PATH_INIT("/lib/modules/%s/build/arch/%s/vdso/vdso.so.dbg", k, a) ||
	    PATH_INIT("/lib/modules/%s/build/arch/%s/kernel/vdso/vdso.so.dbg", k, a) ||
	    PATH_INIT("/lib/modules/%s/build/arch/%s/entry/vdso/vdso32.so.dbg", k, a) ||
	    PATH_INIT("/lib/modules/%s/build/arch/%s/entry/vdso/vdso64.so.dbg", k, a))
		goto out_err;

#undef PATH_INIT

	vdso_path__nr_entries = i;
	return 0;

out_err:
	while (i)
		zfree(&vdso_paths[--i]);
	return -ENOMEM;
}

static void vdso_path__exit(void)
{
	while (vdso_path__nr_entries)
		zfree(&vdso_paths[--vdso_path__nr_entries]);
}

const char *vdso_path(size_t i)
{
	if (i >= vdso_path__nr_entries)
		return NULL;

	return vdso_paths[i];
}

[PATCH v6 5/8] perf: build-id: add support for build-id cache vdso debug

[Changbin Du]

This try to add debugging vdso elf to build-id cache the same as normal
objects. Later we will extend this to find local debugging vdso from
special paths.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/util/build-id.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 83a1581e8cf1..5bda47de5cf2 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -259,8 +259,8 @@ static bool build_id_cache__valid_id(char *sbuild_id)
 static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso,
 					    bool is_debug)
 {
-	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : (is_debug ?
-	    "debug" : "elf"));
+	return is_kallsyms ? "kallsyms" : (is_debug ? "debug" : (is_vdso ?
+		"vdso" : "elf"));
 }
 
 char *__dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
@@ -701,13 +701,12 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
 	 * file itself may not be very useful to users of our tools without a
 	 * symtab.
 	 */
-	if (!is_kallsyms && !is_vdso &&
-	    strncmp(".ko", name + strlen(name) - 3, 3)) {
+	if (!is_kallsyms && strncmp(".ko", name + strlen(name) - 3, 3)) {
 		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
 		if (debugfile) {
 			zfree(&filename);
 			if (asprintf(&filename, "%s/%s", dir_name,
-			    build_id_cache__basename(false, false, true)) < 0) {
+			    build_id_cache__basename(false, is_vdso, true)) < 0) {
 				filename = NULL;
 				goto out_free;
 			}
-- 
2.34.1

Re: [PATCH v6 5/8] perf: build-id: add support for build-id cache vdso debug

[Adrian Hunter]

On 25/07/24 05:15, Changbin Du wrote:
> This try to add debugging vdso elf to build-id cache the same as normal
> objects. Later we will extend this to find local debugging vdso from
> special paths.
> 
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  tools/perf/util/build-id.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 83a1581e8cf1..5bda47de5cf2 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -259,8 +259,8 @@ static bool build_id_cache__valid_id(char *sbuild_id)
>  static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso,
>  					    bool is_debug)
>  {
> -	return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : (is_debug ?
> -	    "debug" : "elf"));
> +	return is_kallsyms ? "kallsyms" : (is_debug ? "debug" : (is_vdso ?
> +		"vdso" : "elf"));
>  }
>  
>  char *__dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
> @@ -701,13 +701,12 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>  	 * file itself may not be very useful to users of our tools without a
>  	 * symtab.
>  	 */
> -	if (!is_kallsyms && !is_vdso &&
> -	    strncmp(".ko", name + strlen(name) - 3, 3)) {
> +	if (!is_kallsyms && strncmp(".ko", name + strlen(name) - 3, 3)) {
>  		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
>  		if (debugfile) {
>  			zfree(&filename);
>  			if (asprintf(&filename, "%s/%s", dir_name,
> -			    build_id_cache__basename(false, false, true)) < 0) {
> +			    build_id_cache__basename(false, is_vdso, true)) < 0) {
>  				filename = NULL;
>  				goto out_free;
>  			}

[PATCH v6 6/8] perf: build-id: extend build_id_cache__find_debug() to find local debugging vdso

[Changbin Du]

Just like vmlinux, try to search vdso in predefined paths when collecting
build-ids. The searched paths usually have debugging info.

For example, the vdso can be found in
/lib/modules/<version>/build/arch/x86/entry/vdso/vdso*.so.dbg for local
build on x86.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Changbin Du <changbin.du@huawei.com>

---
v3:
  - continue to try build_id_cache__find_debug_normal() if
    build_id_cache__find_debug_vdso() failed.
v2:
  - Searching the vdso in record stage instead of report. So the debugging
    vdso will be in build-id cache. This is friendly for cross-machine
    analysis.
---
 tools/perf/util/build-id.c | 48 ++++++++++++++++++++++++++++++++++----
 tools/perf/util/symbol.c   | 17 ++++++++++++++
 tools/perf/util/symbol.h   |  1 +
 3 files changed, 62 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 5bda47de5cf2..67f88b492279 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -593,9 +593,8 @@ static int build_id_cache__add_sdt_cache(const char *sbuild_id,
 #define build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) (0)
 #endif
 
-static char *build_id_cache__find_debug(const char *sbuild_id,
-					struct nsinfo *nsi,
-					const char *root_dir)
+static char *build_id_cache__find_debug_normal(const char *sbuild_id,
+				struct nsinfo *nsi, const char *root_dir)
 {
 	const char *dirname = "/usr/lib/debug/.build-id/";
 	char *realname = NULL;
@@ -646,6 +645,47 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
 	return realname;
 }
 
+static char *build_id_cache__find_debug_vdso(const char *sbuild_id)
+{
+	char sbuild_id_tmp[SBUILD_ID_SIZE];
+	struct build_id bid;
+	int i, ret = 0;
+
+	if (!vdso_paths.paths)
+		return NULL;
+
+	pr_debug("Looking at the vdso_path (%d entries long)\n",
+		 vdso_paths.nr_entries + 1);
+
+	for (i = 0; i < vdso_paths.nr_entries; ++i) {
+		ret = filename__read_build_id(vdso_paths.paths[i], &bid);
+		if (ret < 0)
+			continue;
+
+		build_id__sprintf(&bid, sbuild_id_tmp);
+		if (!strcmp(sbuild_id, sbuild_id_tmp)) {
+			pr_debug("Found debugging vdso %s\n", vdso_paths.paths[i]);
+			return strdup(vdso_paths.paths[i]);
+		}
+	}
+
+	return NULL;
+}
+
+static char *build_id_cache__find_debug(const char *sbuild_id,
+					struct nsinfo *nsi,
+					bool is_vdso,
+					const char *root_dir)
+{
+	char *name = NULL;
+
+	if (is_vdso)
+		name = build_id_cache__find_debug_vdso(sbuild_id);
+	if (!name)
+		name = build_id_cache__find_debug_normal(sbuild_id, nsi, root_dir);
+	return name;
+}
+
 int
 build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
 		    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
@@ -702,7 +742,7 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
 	 * symtab.
 	 */
 	if (!is_kallsyms && strncmp(".ko", name + strlen(name) - 3, 3)) {
-		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
+		debugfile = build_id_cache__find_debug(sbuild_id, nsi, is_vdso, root_dir);
 		if (debugfile) {
 			zfree(&filename);
 			if (asprintf(&filename, "%s/%s", dir_name,
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 6bf75c98e1f2..8e982e68b717 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -49,6 +49,7 @@ static int dso__load_vdso_sym(struct dso *dso, struct map *map);
 static bool symbol__is_idle(const char *name);
 
 struct dso_filename_paths vmlinux_paths;
+struct dso_filename_paths vdso_paths;
 
 struct symbol_conf symbol_conf = {
 	.nanosecs		= false,
@@ -2303,6 +2304,16 @@ struct dso_filename_pattern vmlinux_patterns[] = {
 	{"/usr/lib/debug/boot/vmlinux-%s.debug", 1},
 };
 
+struct dso_filename_pattern vdso_patterns[] = {
+	{"/lib/modules/%s/vdso/vdso.so", 1},
+	{"/lib/modules/%s/vdso/vdso64.so", 1},
+	{"/lib/modules/%s/vdso/vdso32.so", 1},
+	{"/lib/modules/%s/build/arch/%s/vdso/vdso.so.dbg", 2},
+	{"/lib/modules/%s/build/arch/%s/kernel/vdso/vdso.so.dbg", 2},
+	{"/lib/modules/%s/build/arch/%s/entry/vdso/vdso32.so.dbg", 2},
+	{"/lib/modules/%s/build/arch/%s/entry/vdso/vdso64.so.dbg", 2},
+};
+
 static int dso_filename_path__add(struct dso_filename_paths *paths, const char *new_entry)
 {
 	paths->paths[paths->nr_entries] = strdup(new_entry);
@@ -2565,6 +2576,11 @@ int symbol__init(struct perf_env *env)
 		return -1;
 	}
 
+	if (dso_filename_path__init(&vdso_paths, vdso_patterns,
+				    ARRAY_SIZE(vdso_patterns), env) < 0) {
+		return -1;
+	}
+
 	if (symbol_conf.field_sep && *symbol_conf.field_sep == '.') {
 		pr_err("'.' is the only non valid --field-separator argument\n");
 		return -1;
@@ -2641,6 +2657,7 @@ void symbol__exit(void)
 	intlist__delete(symbol_conf.pid_list);
 	intlist__delete(symbol_conf.addr_list);
 	dso_filename_path__exit(&vmlinux_paths);
+	dso_filename_path__exit(&vdso_paths);
 	symbol_conf.sym_list = symbol_conf.dso_list = symbol_conf.comm_list = NULL;
 	symbol_conf.bt_stop_list = NULL;
 	symbol_conf.initialized = false;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 30056884945b..08c339594d4e 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -107,6 +107,7 @@ struct dso_filename_paths {
 };
 
 extern struct dso_filename_paths vmlinux_paths;
+extern struct dso_filename_paths vdso_paths;
 
 static inline void *symbol__priv(struct symbol *sym)
 {
-- 
2.34.1

Re: [PATCH v6 6/8] perf: build-id: extend build_id_cache__find_debug() to find local debugging vdso

[Adrian Hunter]

On 25/07/24 05:15, Changbin Du wrote:
> Just like vmlinux, try to search vdso in predefined paths when collecting
> build-ids. The searched paths usually have debugging info.
> 
> For example, the vdso can be found in
> /lib/modules/<version>/build/arch/x86/entry/vdso/vdso*.so.dbg for local
> build on x86.
> 
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> 
> ---
> v3:
>   - continue to try build_id_cache__find_debug_normal() if
>     build_id_cache__find_debug_vdso() failed.
> v2:
>   - Searching the vdso in record stage instead of report. So the debugging
>     vdso will be in build-id cache. This is friendly for cross-machine
>     analysis.
> ---
>  tools/perf/util/build-id.c | 48 ++++++++++++++++++++++++++++++++++----
>  tools/perf/util/symbol.c   | 17 ++++++++++++++
>  tools/perf/util/symbol.h   |  1 +
>  3 files changed, 62 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> index 5bda47de5cf2..67f88b492279 100644
> --- a/tools/perf/util/build-id.c
> +++ b/tools/perf/util/build-id.c
> @@ -593,9 +593,8 @@ static int build_id_cache__add_sdt_cache(const char *sbuild_id,
>  #define build_id_cache__add_sdt_cache(sbuild_id, realname, nsi) (0)
>  #endif
>  
> -static char *build_id_cache__find_debug(const char *sbuild_id,
> -					struct nsinfo *nsi,
> -					const char *root_dir)
> +static char *build_id_cache__find_debug_normal(const char *sbuild_id,

"normal" is a bit vague.  Perhaps just "__build_id_cache__find_debug"

> +				struct nsinfo *nsi, const char *root_dir)
>  {
>  	const char *dirname = "/usr/lib/debug/.build-id/";
>  	char *realname = NULL;
> @@ -646,6 +645,47 @@ static char *build_id_cache__find_debug(const char *sbuild_id,
>  	return realname;
>  }
>  
> +static char *build_id_cache__find_debug_vdso(const char *sbuild_id)
> +{
> +	char sbuild_id_tmp[SBUILD_ID_SIZE];
> +	struct build_id bid;
> +	int i, ret = 0;
> +
> +	if (!vdso_paths.paths)
> +		return NULL;
> +
> +	pr_debug("Looking at the vdso_path (%d entries long)\n",
> +		 vdso_paths.nr_entries + 1);
> +
> +	for (i = 0; i < vdso_paths.nr_entries; ++i) {
> +		ret = filename__read_build_id(vdso_paths.paths[i], &bid);
> +		if (ret < 0)
> +			continue;
> +
> +		build_id__sprintf(&bid, sbuild_id_tmp);
> +		if (!strcmp(sbuild_id, sbuild_id_tmp)) {
> +			pr_debug("Found debugging vdso %s\n", vdso_paths.paths[i]);
> +			return strdup(vdso_paths.paths[i]);
> +		}
> +	}

Doesn't cover symfs or mount namespace like the other one does.

> +
> +	return NULL;
> +}
> +
> +static char *build_id_cache__find_debug(const char *sbuild_id,
> +					struct nsinfo *nsi,
> +					bool is_vdso,
> +					const char *root_dir)
> +{
> +	char *name = NULL;
> +
> +	if (is_vdso)
> +		name = build_id_cache__find_debug_vdso(sbuild_id);
> +	if (!name)
> +		name = build_id_cache__find_debug_normal(sbuild_id, nsi, root_dir);
> +	return name;
> +}
> +
>  int
>  build_id_cache__add(const char *sbuild_id, const char *name, const char *realname,
>  		    struct nsinfo *nsi, bool is_kallsyms, bool is_vdso,
> @@ -702,7 +742,7 @@ build_id_cache__add(const char *sbuild_id, const char *name, const char *realnam
>  	 * symtab.
>  	 */
>  	if (!is_kallsyms && strncmp(".ko", name + strlen(name) - 3, 3)) {
> -		debugfile = build_id_cache__find_debug(sbuild_id, nsi, root_dir);
> +		debugfile = build_id_cache__find_debug(sbuild_id, nsi, is_vdso, root_dir);
>  		if (debugfile) {
>  			zfree(&filename);
>  			if (asprintf(&filename, "%s/%s", dir_name,
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 6bf75c98e1f2..8e982e68b717 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -49,6 +49,7 @@ static int dso__load_vdso_sym(struct dso *dso, struct map *map);
>  static bool symbol__is_idle(const char *name);
>  
>  struct dso_filename_paths vmlinux_paths;
> +struct dso_filename_paths vdso_paths;
>  
>  struct symbol_conf symbol_conf = {
>  	.nanosecs		= false,
> @@ -2303,6 +2304,16 @@ struct dso_filename_pattern vmlinux_patterns[] = {
>  	{"/usr/lib/debug/boot/vmlinux-%s.debug", 1},
>  };
>  
> +struct dso_filename_pattern vdso_patterns[] = {
> +	{"/lib/modules/%s/vdso/vdso.so", 1},
> +	{"/lib/modules/%s/vdso/vdso64.so", 1},
> +	{"/lib/modules/%s/vdso/vdso32.so", 1},
> +	{"/lib/modules/%s/build/arch/%s/vdso/vdso.so.dbg", 2},
> +	{"/lib/modules/%s/build/arch/%s/kernel/vdso/vdso.so.dbg", 2},
> +	{"/lib/modules/%s/build/arch/%s/entry/vdso/vdso32.so.dbg", 2},
> +	{"/lib/modules/%s/build/arch/%s/entry/vdso/vdso64.so.dbg", 2},
> +};
> +
>  static int dso_filename_path__add(struct dso_filename_paths *paths, const char *new_entry)
>  {
>  	paths->paths[paths->nr_entries] = strdup(new_entry);
> @@ -2565,6 +2576,11 @@ int symbol__init(struct perf_env *env)
>  		return -1;
>  	}
>  
> +	if (dso_filename_path__init(&vdso_paths, vdso_patterns,
> +				    ARRAY_SIZE(vdso_patterns), env) < 0) {
> +		return -1;
> +	}
> +
>  	if (symbol_conf.field_sep && *symbol_conf.field_sep == '.') {
>  		pr_err("'.' is the only non valid --field-separator argument\n");
>  		return -1;
> @@ -2641,6 +2657,7 @@ void symbol__exit(void)
>  	intlist__delete(symbol_conf.pid_list);
>  	intlist__delete(symbol_conf.addr_list);
>  	dso_filename_path__exit(&vmlinux_paths);
> +	dso_filename_path__exit(&vdso_paths);
>  	symbol_conf.sym_list = symbol_conf.dso_list = symbol_conf.comm_list = NULL;
>  	symbol_conf.bt_stop_list = NULL;
>  	symbol_conf.initialized = false;
> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> index 30056884945b..08c339594d4e 100644
> --- a/tools/perf/util/symbol.h
> +++ b/tools/perf/util/symbol.h
> @@ -107,6 +107,7 @@ struct dso_filename_paths {
>  };
>  
>  extern struct dso_filename_paths vmlinux_paths;
> +extern struct dso_filename_paths vdso_paths;
>  
>  static inline void *symbol__priv(struct symbol *sym)
>  {

[PATCH v6 7/8] perf: disasm: prefer debugging files in build-id cache

[Changbin Du]

The build-id cache might have both debugging and non-debugging files. Here
we prefer the debugging version for annotation.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/util/disasm.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 6af9fbec3a95..5f66b3632770 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1162,18 +1162,25 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
 	    !dso__is_kcore(dso))
 		return SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
 
-	build_id_filename = dso__build_id_filename(dso, NULL, 0, false);
-	if (build_id_filename) {
-		__symbol__join_symfs(filename, filename_size, build_id_filename);
-		free(build_id_filename);
-	} else {
-		if (dso__has_build_id(dso))
-			return ENOMEM;
-		return fallback_filename(dso, filename, filename_size);
-	}
+	/* Prefer debugging file if exists, otherwise non-debugging one is used. */
+	for (int i = 0; i < 2; i++) {
+		build_id_filename = dso__build_id_filename(dso, NULL, 0, !i);
+		if (build_id_filename) {
+			__symbol__join_symfs(filename, filename_size, build_id_filename);
+			free(build_id_filename);
+		} else {
+			if (dso__has_build_id(dso))
+				return ENOMEM;
+			return fallback_filename(dso, filename, filename_size);
+		}
 
-	if (access(filename, R_OK))
-		return fallback_filename(dso, filename, filename_size);
+		if (!access(filename, R_OK))
+			break;
+		else if (i != 0) {
+			/* nor debugging or non-debugging is found */
+			return fallback_filename(dso, filename, filename_size);
+		}
+	}
 
 	if (dso__is_kcore(dso) || dso__is_vdso(dso))
 		goto fallback;
-- 
2.34.1

Re: [PATCH v6 7/8] perf: disasm: prefer debugging files in build-id cache

[Adrian Hunter]

On 25/07/24 05:15, Changbin Du wrote:
> The build-id cache might have both debugging and non-debugging files. Here
> we prefer the debugging version for annotation.

As I pointed out before, disassembling a different file
from the one that actually executed can have pitfalls.

If you want this, it needs to be optional, not the default.

But if you take the approach to remove vdso from the buildid
cache, and add back the debug version, then this patch would
not be needed for vdso.

> 
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Changbin Du <changbin.du@huawei.com>
> ---
>  tools/perf/util/disasm.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> index 6af9fbec3a95..5f66b3632770 100644
> --- a/tools/perf/util/disasm.c
> +++ b/tools/perf/util/disasm.c
> @@ -1162,18 +1162,25 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil
>  	    !dso__is_kcore(dso))
>  		return SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
>  
> -	build_id_filename = dso__build_id_filename(dso, NULL, 0, false);
> -	if (build_id_filename) {
> -		__symbol__join_symfs(filename, filename_size, build_id_filename);
> -		free(build_id_filename);
> -	} else {
> -		if (dso__has_build_id(dso))
> -			return ENOMEM;
> -		return fallback_filename(dso, filename, filename_size);
> -	}
> +	/* Prefer debugging file if exists, otherwise non-debugging one is used. */
> +	for (int i = 0; i < 2; i++) {
> +		build_id_filename = dso__build_id_filename(dso, NULL, 0, !i);
> +		if (build_id_filename) {
> +			__symbol__join_symfs(filename, filename_size, build_id_filename);
> +			free(build_id_filename);
> +		} else {
> +			if (dso__has_build_id(dso))
> +				return ENOMEM;
> +			return fallback_filename(dso, filename, filename_size);
> +		}
>  
> -	if (access(filename, R_OK))
> -		return fallback_filename(dso, filename, filename_size);
> +		if (!access(filename, R_OK))
> +			break;
> +		else if (i != 0) {
> +			/* nor debugging or non-debugging is found */
> +			return fallback_filename(dso, filename, filename_size);
> +		}
> +	}
>  
>  	if (dso__is_kcore(dso) || dso__is_vdso(dso))
>  		goto fallback;

[PATCH v6 8/8] perf buildid-cache: recognize vdso when adding files

[Changbin Du]

Identify vdso by file name matching. The vdso objects have name
as vdso[32,64].so[.dbg].

$ perf buildid-cache -a /work/linux/arch/x86/entry/vdso/vdso64.so.dbg

Without this change, adding vdso using above command actually will never
be used.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/builtin-buildid-cache.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index b0511d16aeb6..8edea9044a65 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -172,6 +172,30 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 	return 0;
 }
 
+static bool filename_is_vdso(const char *filename)
+{
+	char *fname, *bname;
+	static const char * const vdso_names[] = {
+		"vdso.so", "vdso32.so", "vdso64.so", "vdsox32.so"
+	};
+
+	fname = strdup(filename);
+	if (!fname) {
+		pr_err("no mememory\n");
+		return false;
+	}
+
+	bname = basename(fname);
+	if (!bname)
+		return false;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(vdso_names); i++) {
+		if (!strncmp(bname, vdso_names[i], strlen(vdso_names[i])))
+			return true;
+	}
+	return false;
+}
+
 static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 {
 	char sbuild_id[SBUILD_ID_SIZE];
@@ -189,7 +213,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 
 	build_id__sprintf(&bid, sbuild_id);
 	err = build_id_cache__add_s(sbuild_id, filename, nsi,
-				    false, false);
+				    false, filename_is_vdso(filename));
 	pr_debug("Adding %s %s: %s\n", sbuild_id, filename,
 		 err ? "FAIL" : "Ok");
 	return err;
-- 
2.34.1

Re: [PATCH v6 8/8] perf buildid-cache: recognize vdso when adding files

[Adrian Hunter]

On 25/07/24 05:15, Changbin Du wrote:
> Identify vdso by file name matching. The vdso objects have name
> as vdso[32,64].so[.dbg].
> 
> $ perf buildid-cache -a /work/linux/arch/x86/entry/vdso/vdso64.so.dbg
> 
> Without this change, adding vdso using above command actually will never
> be used.
> 
> Signed-off-by: Changbin Du <changbin.du@huawei.com>

A couple of comments, but address those then add:

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  tools/perf/builtin-buildid-cache.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
> index b0511d16aeb6..8edea9044a65 100644
> --- a/tools/perf/builtin-buildid-cache.c
> +++ b/tools/perf/builtin-buildid-cache.c
> @@ -172,6 +172,30 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
>  	return 0;
>  }
>  
> +static bool filename_is_vdso(const char *filename)
> +{
> +	char *fname, *bname;
> +	static const char * const vdso_names[] = {
> +		"vdso.so", "vdso32.so", "vdso64.so", "vdsox32.so"
> +	};
> +
> +	fname = strdup(filename);
> +	if (!fname) {
> +		pr_err("no mememory\n");

mememory -> memory

> +		return false;
> +	}

fname is never freed.

> +
> +	bname = basename(fname);
> +	if (!bname)
> +		return false;
> +
> +	for (unsigned int i = 0; i < ARRAY_SIZE(vdso_names); i++) {

'unsigned' is unnecessary

> +		if (!strncmp(bname, vdso_names[i], strlen(vdso_names[i])))

Use strstarts()

> +			return true;
> +	}
> +	return false;
> +}
> +
>  static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
>  {
>  	char sbuild_id[SBUILD_ID_SIZE];
> @@ -189,7 +213,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
>  
>  	build_id__sprintf(&bid, sbuild_id);
>  	err = build_id_cache__add_s(sbuild_id, filename, nsi,
> -				    false, false);
> +				    false, filename_is_vdso(filename));
>  	pr_debug("Adding %s %s: %s\n", sbuild_id, filename,
>  		 err ? "FAIL" : "Ok");
>  	return err;

Re: [PATCH v6 8/8] perf buildid-cache: recognize vdso when adding files

[duchangbin]

On Wed, Sep 11, 2024 at 11:05:20AM +0300, Adrian Hunter wrote:
> On 25/07/24 05:15, Changbin Du wrote:
> > Identify vdso by file name matching. The vdso objects have name
> > as vdso[32,64].so[.dbg].
> > 
> > $ perf buildid-cache -a /work/linux/arch/x86/entry/vdso/vdso64.so.dbg
> > 
> > Without this change, adding vdso using above command actually will never
> > be used.
> > 
> > Signed-off-by: Changbin Du <changbin.du@huawei.com>
> 
> A couple of comments, but address those then add:
> 
> Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
> 
> > ---
> >  tools/perf/builtin-buildid-cache.c | 26 +++++++++++++++++++++++++-
> >  1 file changed, 25 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
> > index b0511d16aeb6..8edea9044a65 100644
> > --- a/tools/perf/builtin-buildid-cache.c
> > +++ b/tools/perf/builtin-buildid-cache.c
> > @@ -172,6 +172,30 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
> >  	return 0;
> >  }
> >  
> > +static bool filename_is_vdso(const char *filename)
> > +{
> > +	char *fname, *bname;
> > +	static const char * const vdso_names[] = {
> > +		"vdso.so", "vdso32.so", "vdso64.so", "vdsox32.so"
> > +	};
> > +
> > +	fname = strdup(filename);
> > +	if (!fname) {
> > +		pr_err("no mememory\n");
> 
> mememory -> memory
>
fixed.

> > +		return false;
> > +	}
> 
> fname is never freed.
> 
fixed.

> > +
> > +	bname = basename(fname);
> > +	if (!bname)
> > +		return false;
> > +
> > +	for (unsigned int i = 0; i < ARRAY_SIZE(vdso_names); i++) {
> 
> 'unsigned' is unnecessary
> 
This is required to supress this error.
error: comparison of integer expressions of different signedness: ‘int’ and ‘long unsigned int’

> > +		if (!strncmp(bname, vdso_names[i], strlen(vdso_names[i])))
> 
> Use strstarts()
> 
okay.

> > +			return true;
> > +	}
> > +	return false;
> > +}
> > +
> >  static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
> >  {
> >  	char sbuild_id[SBUILD_ID_SIZE];
> > @@ -189,7 +213,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
> >  
> >  	build_id__sprintf(&bid, sbuild_id);
> >  	err = build_id_cache__add_s(sbuild_id, filename, nsi,
> > -				    false, false);
> > +				    false, filename_is_vdso(filename));
> >  	pr_debug("Adding %s %s: %s\n", sbuild_id, filename,
> >  		 err ? "FAIL" : "Ok");
> >  	return err;
> 
> 

-- 
Cheers,
Changbin Du

[RESEND PATCH v6 0/8] perf: Support searching local debugging vdso or specify vdso path in cmdline

[Changbin Du]

The vdso dumped from process memory (in buildid-cache) lacks debugging
info. To annotate vdso symbols with source lines we need 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 resides in
'/lib/modules/<version>/vdso/vdso{32,64}.so' on Ubuntu. But notice that the
builid has to match.

If user doesn't specify the path, perf will search them internally as long
as vmlinux when recording samples. The searched debugging vdso will add to
buildid cache as ~/.debug/[vdso]/debug.

Below samples are captured on my local build kernel. perf succesfully
find debugging version vdso and we can annotate with source without
specifying vdso path.

$ sudo perf record -a
$ sudo perf report --objdump=llvm-objdump

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 need to specify the vdso path manually if
we are interested in its symbols, because they are not installed on local
machine. At most two vdso can be given. Also you can pack your buildid cache with
perf-archive if the debugging vdso can be found on the sampled machine.

$ sudo perf report --objdump=llvm-objdump \
      --vdso arch/x86/entry/vdso/vdso64.so.dbg,arch/x86/entry/vdso/vdso32.so.dbg

I also improved perf-buildid-cache command to recognize vdso when adding files,
then place it at correct place.

$ sudo perf buildid-cache --add /work/linux/arch/x86/entry/vdso/vdso64.so.dbg

Then it will be copied to ~/.debug/[vdso]/debug.

v6:
  - split "perf: build-id: try to search debugging vdso and add to cache" 
    by functional logical. (suggested by Adrian)
v5:
  - Searching the vdso in record stage instead of report. So the debugging
    vdso will be in build-id cache. This is friendly for cross-machine analysis.
  - Improve perf-buildid-cache command recognize vdso when adding files
v4:
  - split the refactoring from the actual change.
v3:
  - update documentation.
v2:
  - now search vdso automatically as long as vmlinux, as suggested by Adrian.
  - remove change 'prefer symsrc_filename for filename'.

Changbin Du (8):
  perf: support specify vdso path in cmdline
  perf: disasm: refactor function dso__disassemble_filename
  perf: disasm: use build_id_path if fallback failed
  perf: symbol: generalize vmlinux path searching
  perf: build-id: add support for build-id cache vdso debug
  perf: build-id: extend build_id_cache__find_debug() to find local
    debugging vdso
  perf: disasm: prefer debugging files in build-id cache
  perf buildid-cache: recognize vdso when adding files

 tools/perf/Documentation/perf-annotate.txt |   3 +
 tools/perf/Documentation/perf-c2c.txt      |   3 +
 tools/perf/Documentation/perf-inject.txt   |   3 +
 tools/perf/Documentation/perf-report.txt   |   3 +
 tools/perf/Documentation/perf-script.txt   |   3 +
 tools/perf/Documentation/perf-top.txt      |   3 +
 tools/perf/builtin-annotate.c              |   2 +
 tools/perf/builtin-buildid-cache.c         |  26 ++-
 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/build-id.c                 |  57 +++++-
 tools/perf/util/disasm.c                   | 131 ++++++++-----
 tools/perf/util/machine.c                  |   4 +-
 tools/perf/util/symbol.c                   | 209 ++++++++++++++++-----
 tools/perf/util/symbol.h                   |   9 +-
 tools/perf/util/symbol_conf.h              |   5 +
 19 files changed, 359 insertions(+), 112 deletions(-)

-- 
2.34.1

[PATCH v6 8/8] perf buildid-cache: recognize vdso when adding files

[Changbin Du]

Identify vdso by file name matching. The vdso objects have name
as vdso[32,64].so[.dbg].

$ perf buildid-cache -a /work/linux/arch/x86/entry/vdso/vdso64.so.dbg

Without this change, adding vdso using above command actually will never
be used.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
---
 tools/perf/builtin-buildid-cache.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index b0511d16aeb6..8edea9044a65 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -172,6 +172,30 @@ static int build_id_cache__add_kcore(const char *filename, bool force)
 	return 0;
 }
 
+static bool filename_is_vdso(const char *filename)
+{
+	char *fname, *bname;
+	static const char * const vdso_names[] = {
+		"vdso.so", "vdso32.so", "vdso64.so", "vdsox32.so"
+	};
+
+	fname = strdup(filename);
+	if (!fname) {
+		pr_err("no mememory\n");
+		return false;
+	}
+
+	bname = basename(fname);
+	if (!bname)
+		return false;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(vdso_names); i++) {
+		if (!strncmp(bname, vdso_names[i], strlen(vdso_names[i])))
+			return true;
+	}
+	return false;
+}
+
 static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 {
 	char sbuild_id[SBUILD_ID_SIZE];
@@ -189,7 +213,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
 
 	build_id__sprintf(&bid, sbuild_id);
 	err = build_id_cache__add_s(sbuild_id, filename, nsi,
-				    false, false);
+				    false, filename_is_vdso(filename));
 	pr_debug("Adding %s %s: %s\n", sbuild_id, filename,
 		 err ? "FAIL" : "Ok");
 	return err;
-- 
2.34.1