linux-kernel - Re: [PATCH v3 1/6] remoteproc: Introduce custom dump function for each remoteproc segment

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Date:   Sun, 7 Oct 2018 23:23:33 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        ohad@...ery.com, kyan@...eaurora.org, sricharan@...eaurora.org,
        akdwived@...eaurora.org, linux-arm-msm@...r.kernel.org,
        tsoni@...eaurora.org
Subject: Re: [PATCH v3 1/6] remoteproc: Introduce custom dump function for
 each remoteproc segment

On Fri 27 Jul 08:19 PDT 2018, Sibi Sankar wrote:

> Introduce custom dump function per remoteproc segment. It is responsible
> for filling the device memory segment associated with coredump
> 
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 15 ++++++++++-----
>  include/linux/remoteproc.h           |  3 +++
>  2 files changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 283b258f5e0f..ec56cd822b26 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1183,13 +1183,18 @@ static void rproc_coredump(struct rproc *rproc)
>  		phdr->p_align = 0;
>  
>  		ptr = rproc_da_to_va(rproc, segment->da, segment->size);
> -		if (!ptr) {
> -			dev_err(&rproc->dev,
> +
> +		if (segment->dump) {
> +			segment->dump(rproc, ptr, segment->size, data + offset);

rproc_da_to_va() is an exported symbol, so if you pass segment to the
dump function the driver can, if it needs to, call the function itself.

A typical use case, that I see, is to use the custom dump function to
write out CPU or hardware state to the dump file, in which case the "da"
won't be valid.


So please make this call dump(rproc, segment, data + offset) and move
the rproc_da_to_va() into the else block.

> +		} else {
> +			if (!ptr) {
> +				dev_err(&rproc->dev,
>  				"invalid coredump segment (%pad, %zu)\n",
>  				&segment->da, segment->size);
> -			memset(data + offset, 0xff, segment->size);
> -		} else {
> -			memcpy(data + offset, ptr, segment->size);
> +				memset(data + offset, 0xff, segment->size);
> +			} else {
> +				memcpy(data + offset, ptr, segment->size);
> +			}
>  		}
>  
>  		offset += phdr->p_filesz;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e3c5d856b6da..0fbb01a9955c 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -399,6 +399,8 @@ enum rproc_crash_type {
>   * @node:	list node related to the rproc segment list
>   * @da:		device address of the segment
>   * @size:	size of the segment
> + * @dump:	custom dump function to fill device memory segment associated
> + *		with coredump
>   */
>  struct rproc_dump_segment {
>  	struct list_head node;
> @@ -406,6 +408,7 @@ struct rproc_dump_segment {
>  	dma_addr_t da;
>  	size_t size;
>  
> +	void (*dump)(struct rproc *rproc, void *ptr, size_t len, void *priv);

"priv" isn't the best name to represent the memory to which you expect
dump to write to. Please call it "dest".

>  	loff_t offset;
>  };

Regards,
Bjorn