linux-kernel - [PATCH 1/2] perf tools: Decompress kernel module when reading DSO data

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Date:   Thu,  1 Jun 2017 18:06:04 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel-team@....com,
        David Ahern <dsahern@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH 1/2] 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.  Move decompress_kmodule() to
util/dso.c and do not unlink it immediately.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/dso.c        | 56 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/dso.h        |  2 ++
 tools/perf/util/symbol-elf.c | 40 ++++---------------------------
 3 files changed, 63 insertions(+), 35 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index b27d127cdf68..8dc1f147547c 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -350,6 +350,45 @@ void dso__set_module_info(struct dso *dso, struct kmod_path *m,
 	dso__set_short_name(dso, strdup(m->name), true);
 }
 
+int dso__decompress_kmodule(struct dso *dso, const char *filename,
+			    char *buf, size_t sz)
+{
+	struct kmod_path m = {};
+	int ret = -1;
+	int fd = -1;
+
+	if (!dso__needs_decompress(dso))
+		return -1;
+
+	if (kmod_path__parse_ext(&m, filename) < 0)
+		goto out;
+
+	if (!is_supported_compression(m.ext))
+		goto out;
+
+	snprintf(buf, sz, "/tmp/perf-kmod-XXXXXX");
+
+	fd = mkstemp(buf);
+	if (fd < 0) {
+		dso->load_errno = errno;
+		goto out;
+	}
+
+	pr_debug("decompressing to %s\n", buf);
+	if (!decompress_to_file(m.ext, filename, fd)) {
+		dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
+		unlink(buf);
+		close(fd);
+		goto out;
+	}
+	ret = fd;
+
+out:
+	free(m.ext);
+
+	return ret;
+}
+
 /*
  * Global list of open DSOs and the counter.
  */
@@ -399,6 +438,7 @@ static int __open_dso(struct dso *dso, struct machine *machine)
 	int fd;
 	char *root_dir = (char *)"";
 	char *name = malloc(PATH_MAX);
+	bool needs_unlink = false;
 
 	if (!name)
 		return -ENOMEM;
@@ -415,7 +455,23 @@ static int __open_dso(struct dso *dso, struct machine *machine)
 	if (!is_regular_file(name))
 		return -EINVAL;
 
+	if (dso__needs_decompress(dso)) {
+		char buf[32];
+
+		fd = dso__decompress_kmodule(dso, name, buf, sizeof(buf));
+		if (fd < 0)
+			return -1;
+
+		close(fd);
+		strcpy(name, buf);
+		needs_unlink = true;
+	}
+
 	fd = do_open(name);
+
+	if (needs_unlink)
+		unlink(name);
+
 	free(name);
 	return fd;
 }
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 5fe2ab5877bd..c1e4b94d41aa 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -244,6 +244,8 @@ 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(struct dso *dso, const char *filename,
+			    char *buf, size_t sz);
 
 struct kmod_path {
 	char *name;
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 1fb2efae4f02..b335f91f0cb3 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -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;
@@ -702,9 +668,13 @@ 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);
+		char buf[32];
+
+		fd = dso__decompress_kmodule(dso, name, buf, sizeof(buf));
 		if (fd < 0)
 			return -1;
+
+		unlink(buf);
 	} else {
 		fd = open(name, O_RDONLY);
 		if (fd < 0) {
-- 
2.13.0