Re: [PATCH] remoteproc: zynqmp: Add coredump support

[Mathieu Poirier <mathieu.poirier@linaro.org>]

Hi Leonard,

I have queued patches for this driver that will break this patch.  Please
re-submit when v6.9-rc1 is out and rproc-next has been updated, which should be
around the middle of next week.

Thanks,
Mathieu

On Sat, Mar 16, 2024 at 08:16:42PM +0200, Leonard Crestez wrote:
> Supporting remoteproc coredump requires the platform-specific driver to
> register coredump segments to be dumped. Do this by calling
> rproc_coredump_add_segment for every carveout.
> 
> Also call rproc_coredump_set_elf_info when then rproc is created. If the
> ELFCLASS parameter is not provided then coredump fails with an error.
> Other drivers seem to pass EM_NONE for the machine argument but for me
> this shows a warning in gdb. Pass EM_ARM because this is an ARM R5.
> 
> Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
> ---
> 
> Tests were done by triggering an deliberate crash using remoteproc
> debugfs: echo 2 > /sys/kernel/debug/remoteproc/remoteproc0/crash
> 
> This was tested using RPU apps which use RAM for everything so TCM dump
> was not verified. The freertos-gdb script package showed credible data:
> 
> https://github.com/espressif/freertos-gdb
> 
> The R5 cache is not flushed so RAM might be out of date which is
> actually very bad because information most relevant to determining the
> cause of a crash is lost. Possible workaround would be to flush caches
> in some sort of R5 crash handler? I don't think Linux can do anything
> about this limitation.
> 
> The generated coredump doesn't contain registers, this seems to be a
> limitation shared with other rproc coredumps. It's not clear how the apu
> could access rpu registers on zynqmp, my only idea would be to use the
> coresight dap but that sounds difficult.
> 
> ---
>  drivers/remoteproc/xlnx_r5_remoteproc.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c b/drivers/remoteproc/xlnx_r5_remoteproc.c
> index 4395edea9a64..cfbd97b89c26 100644
> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c
> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
> @@ -484,10 +484,11 @@ static int add_mem_regions_carveout(struct rproc *rproc)
>  			of_node_put(it.node);
>  			return -ENOMEM;
>  		}
>  
>  		rproc_add_carveout(rproc, rproc_mem);
> +		rproc_coredump_add_segment(rproc, rmem->base, rmem->size);
>  
>  		dev_dbg(&rproc->dev, "reserved mem carveout %s addr=%llx, size=0x%llx",
>  			it.node->name, rmem->base, rmem->size);
>  		i++;
>  	}
> @@ -595,10 +596,11 @@ static int add_tcm_carveout_split_mode(struct rproc *rproc)
>  			zynqmp_pm_release_node(pm_domain_id);
>  			goto release_tcm_split;
>  		}
>  
>  		rproc_add_carveout(rproc, rproc_mem);
> +		rproc_coredump_add_segment(rproc, da, bank_size);
>  	}
>  
>  	return 0;
>  
>  release_tcm_split:
> @@ -674,10 +676,11 @@ static int add_tcm_carveout_lockstep_mode(struct rproc *rproc)
>  			goto release_tcm_lockstep;
>  		}
>  
>  		/* If registration is success, add carveouts */
>  		rproc_add_carveout(rproc, rproc_mem);
> +		rproc_coredump_add_segment(rproc, da, bank_size);
>  
>  		dev_dbg(dev, "TCM carveout lockstep mode %s addr=0x%llx, da=0x%x, size=0x%lx",
>  			bank_name, bank_addr, da, bank_size);
>  	}
>  
> @@ -851,10 +854,12 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
>  	if (!r5_rproc) {
>  		dev_err(cdev, "failed to allocate memory for rproc instance\n");
>  		return ERR_PTR(-ENOMEM);
>  	}
>  
> +	rproc_coredump_set_elf_info(r5_rproc, ELFCLASS32, EM_ARM);
> +
>  	r5_rproc->auto_boot = false;
>  	r5_core = r5_rproc->priv;
>  	r5_core->dev = cdev;
>  	r5_core->np = dev_of_node(cdev);
>  	if (!r5_core->np) {
> -- 
> 2.34.1

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