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Date: Fri, 5 Feb 2016 10:57:17 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, Andi Kleen <andi@firstfloor.org>,
        Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Rose Belcher <cel@us.ibm.com>,
        Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
        Sonny Rao <sonnyrao@chromium.org>,
        John Mccutchan <johnmccutchan@google.com>,
        David Ahern <dsahern@gmail.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Pawel Moll <pawel.moll@arm.com>
Subject: Re: [PATCH v8 2/4] perf inject: add jitdump mmap injection support
Message-ID: <20160205135717.GE28242@kernel.org>
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Em Fri, Feb 05, 2016 at 10:51:18AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Feb 05, 2016 at 10:47:31AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Feb 04, 2016 at 03:02:59PM -0800, Stephane Eranian escreveu:
> > > > I'm keeping what I have a perf/jit branch in my git tree.
> > 
> > What am I doing wrong? Continuing to investigate...
> > #7  0x00007fef53f31b3a in strlen () from /lib64/libc.so.6
> > #8  0x00007fef51e8e4c1 in compiled_method_load_cb (jvmti=0x7fef4c003ef0, method=<optimized out>, code_size=520, code_addr=0x7fef3d0ffd00, map_length=<optimized out>, 
> >     map=0x0, compile_info=0x7fef04019e80) at libjvmti.c:85
> 
> 
> Ok, this bandaid cured the segfault:
> 
> 
> -------------------------------------------------------------
> diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
> index 745f20c7b4bd..92ffbe4ff160 100644
> --- a/tools/perf/jvmti/libjvmti.c
> +++ b/tools/perf/jvmti/libjvmti.c
> @@ -82,7 +82,7 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
>  		 * append file name, we use loops and not string ops to avoid modifying
>  		 * class_sign which is used later for the symbol name
>  		 */
> -		for (j = 0; i < (PATH_MAX - 1) && j < strlen(file_name); j++, i++)
> +		for (j = 0; i < (PATH_MAX - 1) && file_name && j < strlen(file_name); j++, i++)
>  			fn[i] = file_name[j];
>  		fn[i] = '\0';
>  	} else {
> -------------------------------------------------------------
> 
> Now:
> 
> [acme@jouet java]$ java -agentpath:/home/acme/git/linux/tools/perf/jvmti/libjvmti.so hello.java 
> java: jvmti: jitdump in /home/acme/.debug/jit/java-jit-20160205.XXdDr2Wr/jit-28322.dump
> Error: Could not find or load main class hello.java
> [acme@jouet java]$
> 
> Do I need to set CLASSPATH or something? /me tries...

Duh:

[acme@jouet java]$ java -agentpath:/home/acme/git/linux/tools/perf/jvmti/libjvmti.so hello
java: jvmti: jitdump in /home/acme/.debug/jit/java-jit-20160205.XXFb472a/jit-28966.dump
Hello, World
[acme@jouet java]$ 

- Arnaldo