linux-kernel - Re: [PATCH 10/31] perf test: Enforce LLVM test for BPF test

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Message-ID: <561F94EE.2060503@huawei.com>
Date:	Thu, 15 Oct 2015 19:58:38 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	<acme@...nel.org>, <ast@...mgrid.com>, <brendan.d.gregg@...il.com>,
	<a.p.zijlstra@...llo.nl>, <daniel@...earbox.net>,
	<dsahern@...il.com>, <hekuang@...wei.com>, <jolsa@...nel.org>,
	<lizefan@...wei.com>, <masami.hiramatsu.pt@...achi.com>,
	<paulus@...ba.org>, <linux-kernel@...r.kernel.org>,
	<pi3orama@....com>, <xiakaixu@...wei.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 10/31] perf test: Enforce LLVM test for BPF test



On 2015/10/14 23:48, Namhyung Kim wrote:
> On Wed, Oct 14, 2015 at 12:41:21PM +0000, Wang Nan wrote:
>> This patch replaces the original toy BPF program with previous introduced
>> bpf-script-example.c. Dynamically embedded it into 'llvm-src.c'.
>>
>> The newly introduced BPF program attaches a BPF program at
>> 'sys_epoll_pwait()', and collect half samples from it. perf itself never
>> use that syscall, so further test can verify their result with it.
>>
>> Since BPF program require LINUX_VERSION_CODE of runtime kernel, this
>> patch computes that code from uname.
>>
>> Since the resuling BPF object is useful for further testcases, this patch
>> introduces 'prepare' and 'cleanup' method to tests, and makes test__llvm()
>> create a MAP_SHARED memory array to hold the resulting object.
>>
>> Signed-off-by: He Kuang <hekuang@...wei.com>
>> Signed-off-by: Wang Nan <wangnan0@...wei.com>
>> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
>> Cc: Alexei Starovoitov <ast@...mgrid.com>
>> Cc: Brendan Gregg <brendan.d.gregg@...il.com>
>> Cc: Daniel Borkmann <daniel@...earbox.net>
>> Cc: David Ahern <dsahern@...il.com>
>> Cc: Jiri Olsa <jolsa@...nel.org>
>> Cc: Kaixu Xia <xiakaixu@...wei.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
>> Cc: Zefan Li <lizefan@...wei.com>
>> Cc: pi3orama@....com
>> Link: http://lkml.kernel.org/n/ebpf-6yw9eg0ej3l4jnqhinngkw86@git.kernel.org
>> ---
> [SNIP]
>
>> +void test__llvm_prepare(void)
>> +{
>> +	p_test_llvm__bpf_result = mmap(NULL, SHARED_BUF_INIT_SIZE,
>> +				       PROT_READ | PROT_WRITE,
>> +				       MAP_SHARED | MAP_ANONYMOUS, -1, 0);
>> +	if (!p_test_llvm__bpf_result)
> It should check MAP_FAILED instead.
>

Fixed by this way:

diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c
index e722e8a..25ddeaf 100644
--- a/tools/perf/tests/llvm.c
+++ b/tools/perf/tests/llvm.c
@@ -199,12 +199,15 @@ void test__llvm_prepare(void)

         for (i = 0; llvm_testcases[i].source; i++) {
                 struct test_llvm__bpf_result *result;
+               void *p;

-               result = mmap(NULL, SHARED_BUF_INIT_SIZE,
-                             PROT_READ | PROT_WRITE,
-                             MAP_SHARED | MAP_ANONYMOUS, -1, 0);
-               if (!result)
+               p = mmap(NULL, SHARED_BUF_INIT_SIZE,
+                        PROT_READ | PROT_WRITE,
+                        MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+               if (p == MAP_FAILED)
                         return;
+
+               result = p;
                 memset((void *)result, '\0', SHARED_BUF_INIT_SIZE);

                 llvm_testcases[i].result = result;

Thank you.

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