perf tools: Introduce dso__decompress_kmodule_{fd,path}

PATCH Superseded Namhyung Kim 3 participants 7 messages Jun 3, 2017 – Jun 6, 2017 perf events

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Namhyung Kim

author maintainer

2017-06-03 02:01 UTC #0 lore raw

PATCH v2 1/3 perf tools: Introduce dso__decompress_kmodule_{fd,path}

Move decompress_kmodule() to util/dso.c and split it to two functions returning fd and (decompressed) file path. Existing user only wants the fd version but the path version will be used soon.

Signed-off-by Namhyung Kim <[email protected]>

---
 tools/perf/util/dso.c        | 51 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/dso.h        |  3 +++
 tools/perf/util/symbol-elf.c | 36 +------------------------------
 3 files changed, 55 insertions(+), 35 deletions(-)

tools/perf/util/dso.c +51 -0

index b27d127cdf68..fc4747a8c283 100644
@@ -248,6 +248,57 @@ bool dso__needs_decompress(struct dso *dso)
 		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
 }
 
+static int decompress_kmodule(struct dso *dso, const char *name, char *tmpbuf)
+{
+	int fd = -1;
+	struct kmod_path m;
+
+	if (!dso__needs_decompress(dso))
+		return -1;
+
+	if (kmod_path__parse_ext(&m, dso->long_name) || !m.comp)
+		return -1;
+
+	fd = mkstemp(tmpbuf);
+	if (fd < 0) {
+		dso->load_errno = errno;
+		goto out;
+	}
+
+	if (!decompress_to_file(m.ext, name, fd)) {
+		dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
+		close(fd);
+		fd = -1;
+	}
+
+out:
+	free(m.ext);
+	return fd;
+}
+
+int dso__decompress_kmodule_fd(struct dso *dso, const char *name)
+{
+	char tmpbuf[] = "/tmp/perf-kmod-XXXXXX";
+	int fd;
+
+	fd = decompress_kmodule(dso, name, tmpbuf);
+	unlink(tmpbuf);
+	return fd;
+}
+
+int dso__decompress_kmodule_path(struct dso *dso, const char *name,
+				 char *pathname, size_t len)
+{
+	char tmpbuf[] = "/tmp/perf-kmod-XXXXXX";
+	int fd;
+
+	fd = decompress_kmodule(dso, name, tmpbuf);
+	close(fd);
+
+	strncpy(pathname, tmpbuf, len);
+	return fd >= 0 ? 0 : fd;
+}
+
 /*
  * Parses kernel module specified in @path and updates
  * @m argument like:

tools/perf/util/dso.h +3 -0

index 5fe2ab5877bd..a2f544990c19 100644
@@ -244,6 +244,9 @@ bool is_supported_compression(const char *ext);
 bool is_kernel_module(const char *pathname, int cpumode);
 bool decompress_to_file(const char *ext, const char *filename, int output_fd);
 bool dso__needs_decompress(struct dso *dso);
+int dso__decompress_kmodule_fd(struct dso *dso, const char *name);
+int dso__decompress_kmodule_path(struct dso *dso, const char *name,
+				 char *pathname, size_t len);
 
 struct kmod_path {
 	char *name;

tools/perf/util/symbol-elf.c +1 ~~-35~~

index 1fb2efae4f02..d342e771dbad 100644
@@ -637,40 +637,6 @@ static int dso__swap_init(struct dso *dso, unsigned char eidata)
 	return 0;
 }
 
-static int decompress_kmodule(struct dso *dso, const char *name,
-			      enum dso_binary_type type)
-{
-	int fd = -1;
-	char tmpbuf[] = "/tmp/perf-kmod-XXXXXX";
-	struct kmod_path m;
-
-	if (type != DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP &&
-	    type != DSO_BINARY_TYPE__GUEST_KMODULE_COMP &&
-	    type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
-		return -1;
-
-	if (kmod_path__parse_ext(&m, dso->long_name) || !m.comp)
-		return -1;
-
-	fd = mkstemp(tmpbuf);
-	if (fd < 0) {
-		dso->load_errno = errno;
-		goto out;
-	}
-
-	if (!decompress_to_file(m.ext, name, fd)) {
-		dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
-		close(fd);
-		fd = -1;
-	}
-
-	unlink(tmpbuf);
-
-out:
-	free(m.ext);
-	return fd;
-}
-
 bool symsrc__possibly_runtime(struct symsrc *ss)
 {
 	return ss->dynsym || ss->opdsec;

@@ -702,7 +668,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
 	int fd;
 
 	if (dso__needs_decompress(dso)) {
-		fd = decompress_kmodule(dso, name, type);
+		fd = dso__decompress_kmodule_fd(dso, name);
 		if (fd < 0)
 			return -1;
 	} else {

Signature · 1 line

2.13.0

Namhyung Kim

author maintainer

2017-06-03 02:01 UTC #1 lore raw

PATCH v2 2/3 perf tools: Decompress kernel module when reading DSO data

Currently perf decompresses kernel modules when loading symbol table but it missed to do it when reading raw data.

Signed-off-by Namhyung Kim <[email protected]>

---
 tools/perf/util/dso.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

tools/perf/util/dso.c +15 -1

index fc4747a8c283..77e5701e38b9 100644
@@ -463,8 +463,22 @@ static int __open_dso(struct dso *dso, struct machine *machine)
 		return -EINVAL;
 	}
 
-	if (!is_regular_file(name))
+	if (!is_regular_file(name)) {
+		free(name);
 		return -EINVAL;
+	}
+
+	if (dso__needs_decompress(dso)) {
+		char newpath[32];
+		size_t len = sizeof(newpath);
+
+		if (dso__decompress_kmodule_path(dso, name, newpath, len) < 0) {
+			free(name);
+			return -1;
+		}
+
+		strcpy(name, newpath);
+	}
 
 	fd = do_open(name);
 	free(name);

Signature · 1 line

2.13.0

Namhyung Kim

author maintainer

2017-06-03 02:01 UTC #2 lore raw

PATCH v2 3/3 perf test: Decompress kernel module before objdump

In reply to Namhyung Kim

If a kernel modules is compressed, it should be decompressed before running objdump to parse binary data correctly. This fixes a failure of object code reading test for me.

Signed-off-by Namhyung Kim <[email protected]>

---
 tools/perf/tests/code-reading.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

tools/perf/tests/code-reading.c +25 -1

index 1f14e7612cbb..fe6bd34d68b1 100644
@@ -229,6 +229,7 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 	unsigned char buf2[BUFSZ];
 	size_t ret_len;
 	u64 objdump_addr;
+	const char *objdump_name;
 	int ret;
 
 	pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);

@@ -289,9 +290,32 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 		state->done[state->done_cnt++] = al.map->start;
 	}
 
+	objdump_name = al.map->dso->long_name;
+	if (dso__needs_decompress(al.map->dso)) {
+		char buf[32];  /* for "/tmp/perf-kmod-XXXXXX" */
+
+		if (dso__decompress_kmodule_path(al.map->dso, objdump_name,
+						 buf, sizeof(buf)) < 0) {
+			pr_debug("decompression failed\n");
+			return -1;
+		}
+
+		objdump_name = strdup(buf);
+		if (objdump_name == NULL) {
+			pr_debug("memory allocation failed\n");
+			return -1;
+		}
+	}
+
 	/* Read the object code using objdump */
 	objdump_addr = map__rip_2objdump(al.map, al.addr);
-	ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
+	ret = read_via_objdump(objdump_name, objdump_addr, buf2, len);
+
+	if (objdump_name != al.map->dso->long_name) {
+		unlink(objdump_name);
+		free((void *)objdump_name);
+	}
+
 	if (ret > 0) {
 		/*
 		 * The kernel maps are inaccurate - assume objdump is right in

Signature · 1 line

2.13.0

Adrian Hunter

reviewer

2017-06-05 11:19 UTC #3 lore raw

Re: [PATCH v2 3/3] perf test: Decompress kernel module before objdump

Quoted 3 lines · Namhyung Kim

If a kernel modules is compressed, it should be decompressed before running objdump to parse binary data correctly. This fixes a failure of object code reading test for me.

Makes sense to me although I have a few small comments below.

Quoted 19 lines

Signed-off-by Namhyung Kim <[email protected]>

---
 tools/perf/tests/code-reading.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

tools/perf/tests/code-reading.c +1 -0

index 1f14e7612cbb..fe6bd34d68b1 100644
@@ -229,6 +229,7 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 	unsigned char buf2[BUFSZ];
 	size_t ret_len;
 	u64 objdump_addr;
+	const char *objdump_name;
 	int ret;
 
 	pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 295

Quoted 6 lines

tools/perf/tests/code-reading.c +3 -0

@@ -289,9 +290,32 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 		state->done[state->done_cnt++] = al.map->start;
 	}
 
+	objdump_name = al.map->dso->long_name;
+	if (dso__needs_decompress(al.map->dso)) {
+		char buf[32];  /* for "/tmp/perf-kmod-XXXXXX" */

We should be able to set the temporary file name buffer size without reference to the format of the name i.e. #define it or use PATH_MAX

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 298

Quoted 3 lines

tools/perf/tests/code-reading.c +3 -0

+
+		if (dso__decompress_kmodule_path(al.map->dso, objdump_name,
+						 buf, sizeof(buf)) < 0) {

Do we care that it is kmodule i.e. why isn't this function called just dso__decompress_path().

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 303

Quoted 5 lines

tools/perf/tests/code-reading.c +5 -0

+			pr_debug("decompression failed\n");
+			return -1;
+		}
+
+		objdump_name = strdup(buf);

Why not just put the buf in the outer scope instead of using strdup().

Quoted 20 lines

tools/perf/tests/code-reading.c +13 -1

+		if (objdump_name == NULL) {
+			pr_debug("memory allocation failed\n");
+			return -1;
+		}
+	}
+
 	/* Read the object code using objdump */
 	objdump_addr = map__rip_2objdump(al.map, al.addr);
-	ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
+	ret = read_via_objdump(objdump_name, objdump_addr, buf2, len);
+
+	if (objdump_name != al.map->dso->long_name) {
+		unlink(objdump_name);
+		free((void *)objdump_name);
+	}
+
 	if (ret > 0) {
 		/*
 		 * The kernel maps are inaccurate - assume objdump is right in

Namhyung Kim

author maintainer

2017-06-06 01:43 UTC #4 lore raw

Re: [PATCH v2 3/3] perf test: Decompress kernel module before objdump

Hi Adrian,

Quoted 6 lines · Adrian Hunter

Quoted 3 lines · Namhyung Kim
If a kernel modules is compressed, it should be decompressed before running objdump to parse binary data correctly. This fixes a failure of object code reading test for me.
Makes sense to me although I have a few small comments below.

Thanks!

Quoted 23 lines

Signed-off-by Namhyung Kim <[email protected]>

---
 tools/perf/tests/code-reading.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

tools/perf/tests/code-reading.c +1 -0

index 1f14e7612cbb..fe6bd34d68b1 100644
@@ -229,6 +229,7 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
      unsigned char buf2[BUFSZ];
      size_t ret_len;
      u64 objdump_addr;
+     const char *objdump_name;
      int ret;
 
      pr_debug("Reading object code for memory address: %#"PRIx64"\n", addr);

@@ -289,9 +290,32 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
              state->done[state->done_cnt++] = al.map->start;
      }

Quoted 6 lines

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 295
Quoted 3 lines
tools/perf/tests/code-reading.c +3 -0
+     objdump_name = al.map->dso->long_name;
+     if (dso__needs_decompress(al.map->dso)) {
+             char buf[32];  /* for "/tmp/perf-kmod-XXXXXX" */
We should be able to set the temporary file name buffer size without reference to the format of the name i.e. #define it or use PATH_MAX

OK, will define KMOD_DECOMP_LEN then..

Quoted 7 lines

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 298
Quoted 4 lines
tools/perf/tests/code-reading.c +3 -0
+
+             if (dso__decompress_kmodule_path(al.map->dso, objdump_name,
+                                              buf, sizeof(buf)) < 0) {
Do we care that it is kmodule i.e. why isn't this function called just dso__decompress_path().

Well, I'm not sure loading a compressed DSO is making sense. Decompressing is needed for kernel modules which supports loading compressed modules.

Quoted 8 lines

tools/perf/tests/code-reading.c static int read_object_code(u64 addr, size_t len, u8 cpumode, · line 303
Quoted 6 lines
tools/perf/tests/code-reading.c +5 -0
+                     pr_debug("decompression failed\n");
+                     return -1;
+             }
+
+             objdump_name = strdup(buf);
Why not just put the buf in the outer scope instead of using strdup().

Will change.

Thanks
Namhyung

Quoted 22 lines

Quoted 21 lines

tools/perf/tests/code-reading.c +13 -1

+             if (objdump_name == NULL) {
+                     pr_debug("memory allocation failed\n");
+                     return -1;
+             }
+     }
+
      /* Read the object code using objdump */
      objdump_addr = map__rip_2objdump(al.map, al.addr);
-     ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
+     ret = read_via_objdump(objdump_name, objdump_addr, buf2, len);
+
+     if (objdump_name != al.map->dso->long_name) {
+             unlink(objdump_name);
+             free((void *)objdump_name);
+     }
+
      if (ret > 0) {
              /*
               * The kernel maps are inaccurate - assume objdump is right in

Jiri Olsa

2017-06-05 09:58 UTC #5 lore raw

In reply to Namhyung Kim

Quoted 16 lines · Namhyung Kim

Move decompress_kmodule() to util/dso.c and split it to two functions returning fd and (decompressed) file path. Existing user only wants the fd version but the path version will be used soon.
Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/dso.c        | 51 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/dso.h        |  3 +++
 tools/perf/util/symbol-elf.c | 36 +------------------------------
 3 files changed, 55 insertions(+), 35 deletions(-)
tools/perf/util/dso.c +0 -0
index b27d127cdf68..fc4747a8c283 100644

tools/perf/util/dso.c bool dso__needs_decompress(struct dso *dso) · line 257

Quoted 10 lines

tools/perf/util/dso.c +7 -0

@@ -248,6 +248,57 @@ bool dso__needs_decompress(struct dso *dso)
 		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
 }
 
+static int decompress_kmodule(struct dso *dso, const char *name, char *tmpbuf)
+{
+	int fd = -1;
+	struct kmod_path m;
+
+	if (!dso__needs_decompress(dso))
+		return -1;

the original code had also DSO_BINARY_TYPE__BUILD_ID_CACHE check, not sure why though.. ;-)

jirka

Namhyung Kim

author maintainer

2017-06-06 01:36 UTC #6 lore raw

Hi Jiri,

Quoted 20 lines · Jiri Olsa

Quoted 19 lines · Namhyung Kim
Move decompress_kmodule() to util/dso.c and split it to two functions returning fd and (decompressed) file path. Existing user only wants the fd version but the path version will be used soon.
Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/dso.c        | 51 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/dso.h        |  3 +++
 tools/perf/util/symbol-elf.c | 36 +------------------------------
 3 files changed, 55 insertions(+), 35 deletions(-)
tools/perf/util/dso.c +0 -0
index b27d127cdf68..fc4747a8c283 100644
@@ -248,6 +248,57 @@ bool dso__needs_decompress(struct dso *dso)
              dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
 }
 

Quoted 10 lines

tools/perf/util/dso.c bool dso__needs_decompress(struct dso *dso) · line 257
Quoted 7 lines
tools/perf/util/dso.c +7 -0
+static int decompress_kmodule(struct dso *dso, const char *name, char *tmpbuf)
+{
+     int fd = -1;
+     struct kmod_path m;
+
+     if (!dso__needs_decompress(dso))
+             return -1;
the original code had also DSO_BINARY_TYPE__BUILD_ID_CACHE check, not sure why though.. ;-)

It's because decompressed modules which were found in the build-id cache didn't set dso->symtab_type properly. It was fixed by my previous patch so checking symtab_type will cover the (compressed) build-id cache case too now.

Thanks,
Namhyung