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Groups > linux.kernel > #1530458

[tip:perf/core] perf tools: Fix kernel version error in ubuntu

From tip-bot for Wang Nan <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:perf/core] perf tools: Fix kernel version error in ubuntu
Date 2016-11-25 18:30 +0100
Message-ID <sHstX-3tw-25@gated-at.bofh.it> (permalink)
References <sDDnX-8py-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  d18acd15c6dfb669f0463afa31ac5343594d2fe2
Gitweb:     http://git.kernel.org/tip/d18acd15c6dfb669f0463afa31ac5343594d2fe2
Author:     Wang Nan <wangnan0@huawei.com>
AuthorDate: Tue, 15 Nov 2016 04:05:44 +0000
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 25 Nov 2016 11:00:30 -0300

perf tools: Fix kernel version error in ubuntu

On ubuntu the internal kernel version code is different from what can
be retrived from uname:

 $ uname -r
 4.4.0-47-generic
 $ cat /lib/modules/`uname -r`/build/include/generated/uapi/linux/version.h
 #define LINUX_VERSION_CODE 263192
 #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
 $ cat /lib/modules/`uname -r`/build/include/generated/utsrelease.h
 #define UTS_RELEASE "4.4.0-47-generic"
 #define UTS_UBUNTU_RELEASE_ABI 47
 $ cat /proc/version_signature
 Ubuntu 4.4.0-47.68-generic 4.4.24

The macro LINUX_VERSION_CODE is set to 4.4.24 (263192 == 0x40418), but
`uname -r` reports 4.4.0.

This mismatch causes LINUX_VERSION_CODE macro passed to BPF script become
an incorrect value, results in magic failure in BPF loading:

 $ sudo ./buildperf/perf record -e ./tools/perf/tests/bpf-script-example.c ls
 event syntax error: './tools/perf/tests/bpf-script-example.c'
                      \___ Failed to load program for unknown reason

According to Ubuntu document (https://wiki.ubuntu.com/Kernel/FAQ), the
correct kernel version can be retrived through /proc/version_signature, which
is ubuntu specific.

This patch checks the existance of /proc/version_signature, and returns
version number through parsing this file instead of uname. Version string
is untouched (value returns from uname) because `uname -r` is required
to be consistence with path of kbuild directory in /lib/module.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161115040617.69788-2-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/util.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 5bbd1f6..67ac765 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -637,12 +637,63 @@ bool find_process(const char *name)
 	return ret ? false : true;
 }
 
+static int
+fetch_ubuntu_kernel_version(unsigned int *puint)
+{
+	ssize_t len;
+	size_t line_len = 0;
+	char *ptr, *line = NULL;
+	int version, patchlevel, sublevel, err;
+	FILE *vsig = fopen("/proc/version_signature", "r");
+
+	if (!vsig) {
+		pr_debug("Open /proc/version_signature failed: %s\n",
+			 strerror(errno));
+		return -1;
+	}
+
+	len = getline(&line, &line_len, vsig);
+	fclose(vsig);
+	err = -1;
+	if (len <= 0) {
+		pr_debug("Reading from /proc/version_signature failed: %s\n",
+			 strerror(errno));
+		goto errout;
+	}
+
+	ptr = strrchr(line, ' ');
+	if (!ptr) {
+		pr_debug("Parsing /proc/version_signature failed: %s\n", line);
+		goto errout;
+	}
+
+	err = sscanf(ptr + 1, "%d.%d.%d",
+		     &version, &patchlevel, &sublevel);
+	if (err != 3) {
+		pr_debug("Unable to get kernel version from /proc/version_signature '%s'\n",
+			 line);
+		goto errout;
+	}
+
+	if (puint)
+		*puint = (version << 16) + (patchlevel << 8) + sublevel;
+	err = 0;
+errout:
+	free(line);
+	return err;
+}
+
 int
 fetch_kernel_version(unsigned int *puint, char *str,
 		     size_t str_size)
 {
 	struct utsname utsname;
 	int version, patchlevel, sublevel, err;
+	bool int_ver_ready = false;
+
+	if (access("/proc/version_signature", R_OK) == 0)
+		if (!fetch_ubuntu_kernel_version(puint))
+			int_ver_ready = true;
 
 	if (uname(&utsname))
 		return -1;
@@ -656,12 +707,12 @@ fetch_kernel_version(unsigned int *puint, char *str,
 		     &version, &patchlevel, &sublevel);
 
 	if (err != 3) {
-		pr_debug("Unablt to get kernel version from uname '%s'\n",
+		pr_debug("Unable to get kernel version from uname '%s'\n",
 			 utsname.release);
 		return -1;
 	}
 
-	if (puint)
+	if (puint && !int_ver_ready)
 		*puint = (version << 16) + (patchlevel << 8) + sublevel;
 	return 0;
 }

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Thread

[PATCH 00/34] perf clang: Builtin clang and perfhook support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 21/34] perf clang: Pass CFLAGS to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 33/34] perf clang builtin: Define hook helpers by default Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 28/34] perf clang jit: Access BPF map Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 16/34] perf clang: Allow passing CFLAGS to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 23/34] perf clang jit: Insignt BPF and JIT functions in a Module Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 02/34] perf record: Fix segfault when running with suid and kptr_restrict is 1 Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
    [tip:perf/core] perf record: Fix segfault when running with suid  and kptr_restrict is 1 tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
  [PATCH 06/34] tools lib bpf: Add private field for bpf_object Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:10 +0100
  [PATCH 03/34] tools perf: Add missing struct defeinition in probe_event.h Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
    [tip:perf/core] perf tools: Add missing struct definition in  probe_event.h tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
  [PATCH 01/34] perf tools: Fix kernel version error in ubuntu Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
    [tip:perf/core] perf tools: Fix kernel version error in ubuntu tip-bot for Wang Nan <tipbot@zytor.com> - 2016-11-25 18:30 +0100
  [PATCH 24/34] perf clang jit: add PerfModule::doJIT to JIT perfhook functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 30/34] perf clang: Link BPF functions declaration into perf Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 11/34] tools build: Add feature detection for LLVM Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 32/34] perf clang: Include helpers to BPF scripts Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 05/34] tools lib bpf: Add missing bpf map functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
    Re: [PATCH 05/34] tools lib bpf: Add missing bpf map functions "Wangnan (F)" <wangnan0@huawei.com> - 2016-11-17 04:30 +0100
      Re: [PATCH 05/34] tools lib bpf: Add missing bpf map functions Arnaldo Carvalho de Melo <acme@redhat.com> - 2016-11-25 15:50 +0100
  [PATCH 31/34] perf clang: Declare BPF functions for BPF scripts automatically Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 29/34] perf clang jit: Allow jitted perf hook access BPF maps Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 34/34] perf clang git: Export getpid() to perf hook Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 09/34] perf tools: Pass context to perf hook functions Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 22/34] perf clang jit: Wrap llvm::Module using PerfModule Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 25/34] perf clang jit: Export functions for jitted code Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 20/34] perf clang: Pass full path to builtin clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 18/34] perf clang: Support compile IR to BPF object and add testcase Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 15/34] perf clang: Use real file system for #include Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 27/34] perf clang jit: Collect the lowest address in maps section as map_base Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 17/34] perf clang: Update test case to use real BPF script Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 13/34] perf build: Add clang and llvm compile and linking support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 12/34] tools build: Add feature detection for clang Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 08/34] perf tools: Introduce perf hooks Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 07/34] tools lib bpf: Retrive bpf_map through offset of bpf_map_def Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 26/34] perf clang jit: Actually JIT and hook in bpf loader Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 14/34] perf clang: Add builtin clang support ant test case Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 10/34] perf llvm: Extract helpers in llvm-utils.c Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  [PATCH 19/34] perf clang: Compile BPF script use builtin clang support Wang Nan <wangnan0@huawei.com> - 2016-11-15 05:20 +0100
  Re: [PATCH 00/34] perf clang: Builtin clang and perfhook support "Wangnan (F)" <wangnan0@huawei.com> - 2016-11-15 05:40 +0100

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