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From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: anshuman.khandual@arm.com, coresight@lists.linaro.org,
	linux-kernel@vger.kernel.org, leo.yan@linaro.org,
	linux-arm-kernel@lists.infradead.org, mike.leach@linaro.org
Subject: Re: [PATCH v6 00/26] coresight: etm4x: Support for system instructions
Date: Fri, 8 Jan 2021 09:08:01 +0000	[thread overview]
Message-ID: <7f3304f7-8c68-3a61-48da-553de87c027d@arm.com> (raw)
In-Reply-To: <20210108010907.GJ43045@xps15>

Hi Mathieu

On 1/8/21 1:09 AM, Mathieu Poirier wrote:
> Hi Suzuki,
> 
> On Thu, Jan 07, 2021 at 12:38:33PM +0000, Suzuki K Poulose wrote:
>> CoreSight ETMv4.4 obsoletes memory mapped access to ETM and
>> mandates the system instructions for registers.
>> This also implies that they may not be on the amba bus.
>> Right now all the CoreSight components are accessed via memory
>> map. Also, we have some common routines in coresight generic
>> code driver (e.g, CS_LOCK, claim/disclaim), which assume the
>> mmio. In order to preserve the generic algorithms at a single
>> place and to allow dynamic switch for ETMs, this series introduces
>> an abstraction layer for accessing a coresight device. It is
>> designed such that the mmio access are fast tracked (i.e, without
>> an indirect function call).
>>
>> This will also help us to get rid of the driver+attribute specific
>> sysfs show/store routines and replace them with a single routine
>> to access a given register offset (which can be embedded in the
>> dev_ext_attribute). This is not currently implemented in the series,
>> but can be achieved.
>>
>> Further we switch the generic routines to work with the abstraction.
>> With this in place, we refactor the etm4x code a bit to allow for
>> supporting the system instructions with very little new code.
>>
>> We use TRCDEVARCH for the detection of the ETM component, which
>> is a standard register as per CoreSight architecture, rather than
>> the etm specific id register TRCIDR1. This is for making sure
>> that we are able to detect the ETM via system instructions accurately,
>> when the the trace unit could be anything (etm or a custom trace unit).
>> To keep the backward compatibility for any existing broken
>> impelementation which may not implement TRCDEVARCH, we fall back to TRCIDR1.
>> Also this covers us for the changes in the future architecture [0].
>>
>> Also, v8.4 self-hosted tracing extensions (coupled with ETMv4.4) adds
>> new filtering registers for trace by exception level. So on a v8.4
>> system, with Trace Filtering support, without the appropriate
>> programming of the Trace filter registers (TRFCR_ELx), tracing
>> will not be enabled. This series also includes the TraceFiltering
>> support to cover the ETM-v4.4 support.
>>
>> The series has been mildly tested on a model for system instructions.
>> I would really appreciate any testing on real hardware.
> 
> I have queued your work in my local tree.  I will have a final pass before
> pushing to coresight-next tomorrow or on Monday.
> 

Thanks for the review and fixups. Please let me know if you need a respin.

Cheers
Suzuki

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  reply	other threads:[~2021-01-08  9:10 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-07 12:38 [PATCH v6 00/26] coresight: etm4x: Support for system instructions Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 01/26] coresight: etm4x: Handle access to TRCSSPCICRn Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 02/26] coresight: etm4x: Skip accessing TRCPDCR in save/restore Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 03/26] coresight: Introduce device access abstraction Suzuki K Poulose
2021-01-07 23:38   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 04/26] coresight: tpiu: Prepare for using coresight " Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 05/26] coresight: Convert coresight_timeout to use " Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 06/26] coresight: Convert claim/disclaim operations to use access wrappers Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 07/26] coresight: etm4x: Always read the registers on the host CPU Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 08/26] coresight: etm4x: Convert all register accesses Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 09/26] coresight: etm4x: Add commentary on the registers Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 10/26] coresight: etm4x: Add sysreg access helpers Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 11/26] coresight: etm4x: Define DEVARCH register fields Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 12/26] coresight: etm4x: Check for Software Lock Suzuki K Poulose
2021-01-08  0:18   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 13/26] coresight: etm4x: Cleanup secure exception level masks Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 14/26] coresight: etm4x: Clean up " Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 15/26] coresight: etm4x: Handle ETM architecture version Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 16/26] coresight: etm4x: Detect access early on the target CPU Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 17/26] coresight: etm4x: Use TRCDEVARCH for component discovery Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 18/26] coresight: etm4x: Expose trcdevarch via sysfs Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 19/26] coresight: etm4x: Add necessary synchronization for sysreg access Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 20/26] coresight: etm4x: Detect system instructions support Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 21/26] coresight: etm4x: Refactor probing routine Suzuki K Poulose
2021-01-08  0:38   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 22/26] coresight: etm4x: Run arch feature detection on the CPU Suzuki K Poulose
2021-01-08  0:49   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 23/26] coresight: etm4x: Add support for sysreg only devices Suzuki K Poulose
2021-01-08  0:55   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 24/26] dts: bindings: coresight: ETM system register access only units Suzuki K Poulose
2021-01-07 12:38 ` [PATCH v6 25/26] arm64: Add TRFCR_ELx definitions Suzuki K Poulose
2021-01-08  1:01   ` Mathieu Poirier
2021-01-07 12:38 ` [PATCH v6 26/26] coresight: Add support for v8.4 SelfHosted tracing Suzuki K Poulose
2021-01-08  1:02   ` Mathieu Poirier
2021-01-08  1:09 ` [PATCH v6 00/26] coresight: etm4x: Support for system instructions Mathieu Poirier
2021-01-08  9:08   ` Suzuki K Poulose [this message]
2021-01-08 14:15     ` Suzuki K Poulose

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