Thread (6 messages) 6 messages, 3 authors, 2018-08-30

[PATCH] perf annotate: fix parsing aarch64 branch instructions after objdump update

From: Thomas-Mich Richter <hidden>
Date: 2018-08-24 07:59:36
Also in: linux-perf-users, lkml

On 08/24/2018 02:10 AM, Kim Phillips wrote:
Starting with binutils 2.28, aarch64 objdump adds comments to the
disassembly output to show the alternative names of a condition code [1].

It is assumed that commas in objdump comments could occur in other arches
now or in the future, so this fix is arch-independent.

The fix could have been done with arm64 specific jump__parse and
jump__scnprintf functions, but the jump__scnprintf instruction would
have to have its comment character be a literal, since the scnprintf
functions cannot receive a struct arch easily.

This inconvenience also applies to the generic jump__scnprintf, which
is why we add a raw_comment pointer to struct ins_operands, so the
__parse function assigns it to be re-used by its corresponding __scnprintf
function.

Example differences in 'perf annotate --stdio2' output on an
aarch64 perf.data file:

BEFORE: ? b.cs   ffff200008133d1c <unwind_frame+0x18c>  // b.hs, dffff7ecc47b
AFTER : ? b.cs   18c

BEFORE: ? b.cc   ffff200008d8d9cc <get_alloc_profile+0x31c>  // b.lo, b.ul, dffff727295b
AFTER : ? b.cc   31c

The branch target labels 18c and 31c also now appear in the output:

BEFORE:        add    x26, x29, #0x80
AFTER : 18c:   add    x26, x29, #0x80

BEFORE:        add    x21, x21, #0x8
AFTER : 31c:   add    x21, x21, #0x8

The Fixes: tag below is added so stable branches will get the update; it
doesn't necessarily mean that commit was broken at the time, rather it
didn't withstand the aarch64 objdump update.

Tested no difference in output for sample x86_64, power arch perf.data files.
Tested,  no difference in output on s390. Just to let you know.
-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
Vorsitzende des Aufsichtsrats: Martina Koederitz 
Gesch?ftsf?hrung: Dirk Wittkopp
Sitz der Gesellschaft: B?blingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
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