linux-kernel - Re: [PATCH 0/2] ARM64: perf: add support for the perf registers and dwarf unwinding

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Message-ID: <CAORVsuUi+C=2pX1YuQY=yirqb5a8oQwzOfWzx85rdzbspd596Q@mail.gmail.com>
Date:	Thu, 14 Nov 2013 12:15:18 +0100
From:	Jean Pihet <jean.pihet@...oldbits.com>
To:	Sandeepa Prabhu <sandeepa.prabhu@...aro.org>
Cc:	Jean Pihet <jean.pihet@...aro.org>,
	Will Deacon <will.deacon@....com>,
	Jiri Olsa <jolsa@...hat.com>,
	Arnaldo <acme@...stprotocols.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Patch Tracking <patches@...aro.org>
Subject: Re: [PATCH 0/2] ARM64: perf: add support for the perf registers and
 dwarf unwinding

Hi Sandeepa,

On Thu, Nov 14, 2013 at 12:04 PM, Sandeepa Prabhu
<sandeepa.prabhu@...aro.org> wrote:
> Hi Jean,
>
> I have applied this patchset on aarch64 upstream branch,cross-compiled
> for arm64 and try running some tests for hardware breakpoints.
>
> I cross-compiled perf using linaro toolchain
> "gcc-linaro-aarch64-linux-gnu-4.7-2013.04-20130415_linux" as
>  $ cd tools/perf/
>  $ make LDFLAGS=-static ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
>
> Copied the static binary to my initrd image and tried running tests to
> place hw_breakpoint on an kernel symbol as:
>
>  # perf record -e "mem:0xffffffc00013f640:x"
> 737
> 738  usage: perf record [<options>] [<command>]
> 739     or: perf record [<options>] -- <command> [<options>]
> 740
> 741     -e, --event <event>   event selector. use 'perf list' to list
> available events
> 742         --filter <filter>
> 743                           event filter
> 744     -p, --pid <pid>       record events on existing process id
> .....
>
> Somehow perf is not able run record, seems not accepting any
> arguments. Do you have any idea what could be going wrong?
Is the behavior caused by this very patch set? This patch set is about
callchain unwinding, which is unrelated to the hardward breakpoint
feature.
Is perf list reporting something? Can you check the '-e mem' command
correctness?

> How did you
> verify/cross-compile perf? Is the tool-chain version wrong?
Since perf depends on external libraries it is not straight forward to
cross compile it. You can compile it as part of a build system (for
example an OE based build system), or compile it natively on the
target.
I am compiling perf and the libraries (libunwind) natively in my case.

>
> Thanks,
> Sandeepa

Please let me know how it goes.

Jean

>
> On 18 October 2013 20:24, Jean Pihet <jean.pihet@...aro.org> wrote:
>> From: Jean Pihet <jean.pihet@...oldbits.com>
>>
>> This patch implements the functions required for the perf registers API,
>> allowing the perf tool to interface kernel register dumps with libunwind
>> in order to provide userspace backtracing.
>> Only the general purpose user space registers are exported, i.e.:
>>  PERF_REG_ARM_X0,
>>  ...
>>  PERF_REG_ARM_X28,
>>  PERF_REG_ARM_FP,
>>  PERF_REG_ARM_LR,
>>  PERF_REG_ARM_SP,
>>  PERF_REG_ARM_PC
>> and not the PERF_REG_ARM_V* registers.
>>
>> Dependencies:
>>  . if present, libunwind >= 1.1 is needed to prevent a segfault when
>>    parsing the dwarf info,
>>  . libunwind needs to be configured with --enable-debug-frame. Note:
>>    --enable-debug-frame is automatically selected on ARM, NOT on ARM64.
>>
>> The generated perf binary has been tested on ARMv8 (using the
>> foundation model simulator) and x86_64, using the following commands:
>>  perf record -g [fp,dwarf] -- <binary>
>>  perf report --sort symbol --call-graph --stdio
>>
>>
>> Jean Pihet (2):
>>   ARM64: perf: add support for perf registers API
>>   ARM64: perf: wire up perf_regs and unwind support
>>
>>  arch/arm64/Kconfig                        |  2 +
>>  arch/arm64/include/uapi/asm/Kbuild        |  1 +
>>  arch/arm64/include/uapi/asm/perf_regs.h   | 40 ++++++++++++++
>>  arch/arm64/kernel/Makefile                |  1 +
>>  arch/arm64/kernel/perf_regs.c             | 29 ++++++++++
>>  tools/perf/arch/arm64/Makefile            |  7 +++
>>  tools/perf/arch/arm64/include/perf_regs.h | 88 +++++++++++++++++++++++++++++++
>>  tools/perf/arch/arm64/util/dwarf-regs.c   | 81 ++++++++++++++++++++++++++++
>>  tools/perf/arch/arm64/util/unwind.c       | 82 ++++++++++++++++++++++++++++
>>  tools/perf/config/Makefile                |  6 +++
>>  10 files changed, 337 insertions(+)
>>  create mode 100644 arch/arm64/include/uapi/asm/perf_regs.h
>>  create mode 100644 arch/arm64/kernel/perf_regs.c
>>  create mode 100644 tools/perf/arch/arm64/Makefile
>>  create mode 100644 tools/perf/arch/arm64/include/perf_regs.h
>>  create mode 100644 tools/perf/arch/arm64/util/dwarf-regs.c
>>  create mode 100644 tools/perf/arch/arm64/util/unwind.c
>>
>> --
>> 1.7.11.7
>>
>> --
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