[PATCH] coresight: tmc-etr: Fix barrier packet insertion for perf buffer

[PATCH] coresight: tmc-etr: Fix barrier packet insertion for perf buffer

[Suzuki K Poulose]

When the ETR is used in perf mode with a larger buffer (configured
via sysfs or the default size of 1M) than the perf aux buffer size,
we end up inserting the barrier packet at the wrong offset, while
moving the offset forward. i.e, instead of the "new moved offset",
we insert it at the current hardware buffer offset. These packets
will not be visible as they are never copied and could lead to
corruption in the trace decoding side, as the decoder is not aware
that it needs to reset the decoding.

Fixes: ec13c78d7b45 ("coresight: tmc-etr: Add barrier packets when moving offset forward")
Reported-by: Al Grant <al.grant@arm.com>
Tested-by: Mike Leach <mike.leach@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index a31a4d7ae25e..bf5230e39c5b 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1552,7 +1552,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 
 	/* Insert barrier packets at the beginning, if there was an overflow */
 	if (lost)
-		tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
+		tmc_etr_buf_insert_barrier_packet(etr_buf, offset);
 	tmc_etr_sync_perf_buffer(etr_perf, offset, size);
 
 	/*
-- 
2.24.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] coresight: tmc-etr: Fix barrier packet insertion for perf buffer

[Mathieu Poirier]

On Mon, Nov 30, 2020 at 02:36:02PM +0000, Suzuki K Poulose wrote:
> When the ETR is used in perf mode with a larger buffer (configured
> via sysfs or the default size of 1M) than the perf aux buffer size,
> we end up inserting the barrier packet at the wrong offset, while
> moving the offset forward. i.e, instead of the "new moved offset",
> we insert it at the current hardware buffer offset. These packets
> will not be visible as they are never copied and could lead to
> corruption in the trace decoding side, as the decoder is not aware
> that it needs to reset the decoding.
> 
> Fixes: ec13c78d7b45 ("coresight: tmc-etr: Add barrier packets when moving offset forward")
> Reported-by: Al Grant <al.grant@arm.com>
> Tested-by: Mike Leach <mike.leach@arm.com>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>  drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index a31a4d7ae25e..bf5230e39c5b 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1552,7 +1552,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
>  
>  	/* Insert barrier packets at the beginning, if there was an overflow */
>  	if (lost)
> -		tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
> +		tmc_etr_buf_insert_barrier_packet(etr_buf, offset);

I have applied this patch.

Thanks,
Mathieu

>  	tmc_etr_sync_perf_buffer(etr_perf, offset, size);
>  
>  	/*
> -- 
> 2.24.1
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel