linux-kernel - Re: [PATCH V5 0/8] perf: Expand perf_branch

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Date:   Mon, 18 Apr 2022 12:17:53 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        peterz@...radead.org, acme@...nel.org
Cc:     Robin Murphy <robin.murphy@....com>,
        Suzuki Poulose <suzuki.poulose@....com>,
        James Clark <james.clark@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V5 0/8] perf: Expand perf_branch_entry



On 4/11/22 11:16, Anshuman Khandual wrote:
> 
> 
> On 4/4/22 10:20, Anshuman Khandual wrote:
>> Branch Record Buffer Extension (BRBE) implementation on arm64 captures more
>> branch type classification which cannot be accommodated in the current perf
>> branch record format via perf_branch_entry.type element (4 bit field). Also
>> it captures privilege information which does not have a corresponding slot
>> in perf_branch_entry. This series expands struct perf_branch_entry, to meet
>> both these requirements without breaking the existing user space ABI for
>> perf tools.
>>
>> All architecture specific branch types added via perf_branch_entry.new_type
>> field in [PATCH 3/4] will be used in BRBE implementation on arm64 platform
>> later on with the following map.
>>
>> #ifdef CONFIG_ARM64
>> #define PERF_BR_FIQ		PERF_BR_NEW_ARCH_1
>> #define PERF_BR_DEBUG_HALT	PERF_BR_NEW_ARCH_2
>> #define PERF_BR_DEBUG_EXIT	PERF_BR_NEW_ARCH_3
>> #define PERF_BR_DEBUG_INST	PERF_BR_NEW_ARCH_4
>> #define PERF_BR_DEBUG_DATA	PERF_BR_NEW_ARCH_5
>> #endif
>>
>> This actually combines following patches and series into a single series.
>>
>> - https://lore.kernel.org/all/1642998653-21377-12-git-send-email-anshuman.khandual@arm.com/
>> - https://lore.kernel.org/all/1643348653-24367-1-git-send-email-anshuman.khandual@arm.com/
>> - https://lore.kernel.org/all/1645681014-3346-1-git-send-email-anshuman.khandual@arm.com/
>>
>> This series applies on v5.18-rc1
>>
>> perf API
>>
>> The series being applied
>>
>> - Clean : tools/perf/check-headers.sh
>> - Clean : diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h
>>
>> Todo
>>
>> - Update perf report tool to process PERF_BR_EXTEND_ABI (when available),
>>   then fetch and report branch types from perf_branch_entry.new_type field.
>>
>> References
>>
>> - BRBE captured branch record information
>>
>> https://developer.arm.com/documentation/ddi0601/2021-12/AArch64-Registers/BRBINF-n--EL1--Branch-Record-Buffer-Information-Register--n-?lang=en
>>
>> - BRBE based perf branch stack implementation on arm64 platform
>>
>> https://lore.kernel.org/all/1642998653-21377-1-git-send-email-anshuman.khandual@arm.com/
>>
>> Changes in V5:
>>
>> - Dropped patches [PATCH 1/10] and [PATCH 6/10] related to PERF_BR_[RET|IRQ] - merged
>>   via the commit cedd3614e5d9c809 ("perf: Add irq and exception return branch types")
>>
>> - Rebased series on v5.18-rc1
> 
> Gentle ping, any updates on this series ?

Gentle ping, any updates on this series ?

I have posted BRBE RFC V2 accommodating all these new perf ABI changes being
proposed here. I would really appreciate reviews and/or suggestions on this
series, which is essential and also prerequisite for the BRBE driver itself.

https://lore.kernel.org/all/20220412115455.293119-1-anshuman.khandual@arm.com/

- Anshuman