[PATCH 3/3] perf tools: Add libdw DWARF post unwind support for ARM64

Jean Pihet jean.pihet at linaro.org
Tue May 6 10:41:55 PDT 2014

Hi Will,

On 6 May 2014 19:00, Will Deacon <will.deacon at arm.com> wrote:
> Hi Jean,
> On Tue, May 06, 2014 at 04:55:33PM +0100, Jean Pihet wrote:
>> Adding libdw DWARF post unwind support, which is part
>> of elfutils-devel/libdw-dev package from version 0.158.
>> Note: the libdw code needs some support for dwarf unwinding
>> on ARM64, this code is submitted seperately on the elfutils
>> ML.
>> The new code is contained in unwin-libdw.c object, and
>> implements unwind__get_entries unwind interface function.
> Are you planning to implement support for 32-bit ARM too? If so, we'll need
> compat handling here again (your favourite!).
Yes! Another patch set (sent just before this one) targets ARM. There
is a nice ToDo in the cover letter: handle compat mode correctly. In
fact I sent a patch to libdw, so it supports it already but is
somewhat broken for compat mode. This is on my prefered ToDo list ;-)

>> +bool libdw__arch_set_initial_registers(Dwfl_Thread *thread, void *arg)
>> +{
>> +     struct unwind_info *ui = arg;
>> +     struct regs_dump *user_regs = &ui->sample->user_regs;
>> +     Dwarf_Word dwarf_regs[PERF_REG_ARM64_MAX];
> Shouldn't this be PERF_REG_ARM64_MAX - 1?
Ah, well spotted! I will change although it shouldn't harm, right?

> Will

Thx for reviewing,

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