linux-kernel - Re: [PATCH 5.4 245/434] perf probe: Fix to list probe event with correct line number

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Message-ID: <f01f3d9a-8b09-7b49-2364-7308f3521d54@mageia.org>
Date:   Mon, 30 Dec 2019 01:00:14 +0200
From:   Thomas Backlund <tmb@...eia.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>
CC:     <stable@...r.kernel.org>, Masami Hiramatsu <mhiramat@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.4 245/434] perf probe: Fix to list probe event with
 correct line number

Den 29-12-2019 kl. 20:42, skrev Thomas Backlund:
> Den 29-12-2019 kl. 19:24, skrev Greg Kroah-Hartman:
>> From: Masami Hiramatsu <mhiramat@...nel.org>
>>
>> [ Upstream commit 3895534dd78f0fd4d3f9e05ee52b9cdd444a743e ]
>>
>> Since debuginfo__find_probe_point() uses dwarf_entrypc() for finding the
>> entry address of the function on which a probe is, it will fail when the
>> function DIE has only ranges attribute.
>>
>> To fix this issue, use die_entrypc() instead of dwarf_entrypc().
>>
>> Without this fix, perf probe -l shows incorrect offset:
>>
>>    # perf probe -l
>>      probe:clear_tasks_mm_cpumask (on 
>> clear_tasks_mm_cpumask+18446744071579263632@...k/linux/linux/kernel/cpu.c) 
>>
>>      probe:clear_tasks_mm_cpumask_1 (on 
>> clear_tasks_mm_cpumask+18446744071579263752@...k/linux/linux/kernel/cpu.c) 
>>
>>
>> With this:
>>
>>    # perf probe -l
>>      probe:clear_tasks_mm_cpumask (on 
>> clear_tasks_mm_cpumask@...k/linux/linux/kernel/cpu.c)
>>      probe:clear_tasks_mm_cpumask_1 (on 
>> clear_tasks_mm_cpumask:21@...k/linux/linux/kernel/cpu.c)
>>
>> Committer testing:
>>
>> Before:
>>
>>    [root@...co ~]# perf probe -l
>>      probe:clear_tasks_mm_cpumask (on 
>> clear_tasks_mm_cpumask+18446744071579765152@...nel/cpu.c)
>>    [root@...co ~]#
>>
>> After:
>>
>>    [root@...co ~]# perf probe -l
>>      probe:clear_tasks_mm_cpumask (on 
>> clear_tasks_mm_cpumask@...nel/cpu.c)
>>    [root@...co ~]#
>>
>> Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number 
>> with inline function")
>> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
>> Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Link: 
>> http://lore.kernel.org/lkml/157199321227.8075.14655572419136993015.stgit@devnote2 
>>
>> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>> ---
>>   tools/perf/util/probe-finder.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/probe-finder.c 
>> b/tools/perf/util/probe-finder.c
>> index cd9f95e5044e..7c8d30fb2b99 100644
>> --- a/tools/perf/util/probe-finder.c
>> +++ b/tools/perf/util/probe-finder.c
>> @@ -1578,7 +1578,7 @@ int debuginfo__find_probe_point(struct debuginfo 
>> *dbg, unsigned long addr,
>>           /* Get function entry information */
>>           func = basefunc = dwarf_diename(&spdie);
>>           if (!func ||
>> -            dwarf_entrypc(&spdie, &baseaddr) != 0 ||
>> +            die_entrypc(&spdie, &baseaddr) != 0 ||
>>               dwarf_decl_line(&spdie, &baseline) != 0) {
>>               lineno = 0;
>>               goto post;
>> @@ -1595,7 +1595,7 @@ int debuginfo__find_probe_point(struct debuginfo 
>> *dbg, unsigned long addr,
>>           while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
>>                           &indie)) {
>>               /* There is an inline function */
>> -            if (dwarf_entrypc(&indie, &_addr) == 0 &&
>> +            if (die_entrypc(&indie, &_addr) == 0 &&
>>                   _addr == addr) {
>>                   /*
>>                    * addr is at an inline function entry.
>>
> 
> 
> still broken
> 
> /usr/bin/ld: perf-in.o: in function `debuginfo__find_probe_point':
> /work/rpmbuild/BUILD/kernel-x86_64/linux-5.4/tools/perf/util/probe-finder.c:1616: 
> undefined reference to `die_entrypc'
> 


And the fix for the perf build errors I reported against:
[PATCH 5.4 245/434] perf probe: Fix to list probe event with correct 
line number
[PATCH 5.4 248/434] perf probe: Fix to probe an inline function which 
has no entry pc
[PATCH 5.4 249/434] perf probe: Fix to show ranges of variables in 
functions without entry_pc
[PATCH 5.4 250/434] perf probe: Fix to show inlined function callsite 
without entry_pc
[PATCH 5.4 252/434] perf probe: Fix to probe a function which has no 
entry pc

is to add the missing:

 From 91e2f539eeda26ab00bd03fae8dc434c128c85ed Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@...nel.org>
Date: Thu, 24 Oct 2019 18:12:54 +0900
Subject: [PATCH] perf probe: Fix to show function entry line as probe-able


--
Thomas