linux-kernel - Re: [PATCH V3 10/10] perf tools: allow annotation using /proc/kcore

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Date:	Tue, 06 Aug 2013 13:11:53 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC:	linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH V3 10/10] perf tools: allow annotation using /proc/kcore

On 05/08/13 22:59, Arnaldo Carvalho de Melo wrote:
> Em Fri, Aug 02, 2013 at 01:10:52PM +0300, Adrian Hunter escreveu:
>> Annotation with /proc/kcore is possible so the logic
>> is adjusted to allow it.  The main difference is that
>> /proc/kcore had no symbols so the parsing logic needed
>> a tweak to read jump offsets.
>>
>> The other difference is that objdump cannot always
>> read from kcore.  That seems to be a bug with objdump.
> 
> Was this reported to the objdump guys? Can you ellaborate on the failure
> cases?

Bug is here:

	http://sourceware.org/bugzilla/show_bug.cgi?id=15818

It appears to fail because /proc/kcore has extremely large segments and
objdump seems to be trying to do something with mmap related to those sizes.

Anything in the text segment is ok.  Anything else (e.g. module addresses)
fails.

> 
>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>>  tools/perf/builtin-top.c   |  3 ++-
>>  tools/perf/util/annotate.c | 13 +++++++++----
>>  2 files changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
>> index bbf4635..3b19a6b 100644
>> --- a/tools/perf/builtin-top.c
>> +++ b/tools/perf/builtin-top.c
>> @@ -103,7 +103,8 @@ static int perf_top__parse_source(struct perf_top *top, struct hist_entry *he)
>>  	/*
>>  	 * We can't annotate with just /proc/kallsyms
>>  	 */
>> -	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
>> +	if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
>> +	    !dso__is_kcore(map->dso)) {
>>  		pr_err("Can't annotate %s: No vmlinux file was found in the "
>>  		       "path\n", sym->name);
>>  		sleep(1);
>> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
>> index d102716..4ab2f11 100644
>> --- a/tools/perf/util/annotate.c
>> +++ b/tools/perf/util/annotate.c
>> @@ -110,10 +110,10 @@ static int jump__parse(struct ins_operands *ops)
>>  {
>>  	const char *s = strchr(ops->raw, '+');
>>  
>> -	ops->target.addr = strtoll(ops->raw, NULL, 16);
>> +	ops->target.addr = strtoull(ops->raw, NULL, 16);
>>  
>>  	if (s++ != NULL)
>> -		ops->target.offset = strtoll(s, NULL, 16);
>> +		ops->target.offset = strtoull(s, NULL, 16);
>>  	else
>>  		ops->target.offset = UINT64_MAX;
>>  
>> @@ -821,6 +821,10 @@ static int symbol__parse_objdump_line(struct symbol *sym, struct map *map,
>>  	if (dl == NULL)
>>  		return -1;
>>  
>> +	if (dl->ops.target.offset == UINT64_MAX)
>> +		dl->ops.target.offset = dl->ops.target.addr -
>> +					map__rip_2objdump(map, sym->start);
>> +
>>  	disasm__add(&notes->src->source, dl);
>>  
>>  	return 0;
>> @@ -864,7 +868,8 @@ fallback:
>>  		free_filename = false;
>>  	}
>>  
>> -	if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
>> +	if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
>> +	    !dso__is_kcore(dso)) {
>>  		char bf[BUILD_ID_SIZE * 2 + 16] = " with build id ";
>>  		char *build_id_msg = NULL;
>>  
>> @@ -898,7 +903,7 @@ fallback:
>>  	snprintf(command, sizeof(command),
>>  		 "%s %s%s --start-address=0x%016" PRIx64
>>  		 " --stop-address=0x%016" PRIx64
>> -		 " -d %s %s -C %s|grep -v %s|expand",
>> +		 " -d %s %s -C %s 2>/dev/null|grep -v %s|expand",
>>  		 objdump_path ? objdump_path : "objdump",
>>  		 disassembler_style ? "-M " : "",
>>  		 disassembler_style ? disassembler_style : "",
>> -- 
>> 1.7.11.7
> 
> 

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