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

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Date:   Sat,  3 Jun 2017 11:00:33 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        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 v2 3/3] perf test: Decompress kernel module before objdump

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 <namhyung@...nel.org>
---
 tools/perf/tests/code-reading.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 1f14e7612cbb..fe6bd34d68b1 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -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
-- 
2.13.0