Re: [PATCH 9/9] remoteproc: Always perserve resource table data

[Ido Yariv]

Hi Sjur,

On Sun, Feb 10, 2013 at 12:39:12PM +0100, sjur.brandeland@xxxxxxxxxxxxxx wrote:
> From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
> 
> Copy resource table from first to second firmware loading.
> After firmware is loaded to memory, update the vdevs resource
> pointer to the resource table kept in device memory.
> 
> Signed-off-by: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
> ---
>  drivers/remoteproc/remoteproc_core.c |   61 +++++++++++++++++++++++++++------
>  include/linux/remoteproc.h           |    3 ++
>  2 files changed, 53 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 14f40eb..13dc7b4 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -694,17 +694,16 @@ static rproc_handle_resource_t rproc_handle_notifyid_rsc[RSC_LAST] = {
>  
>  /* handle firmware resource entries before booting the remote processor */
>  static int
> -rproc_handle_resource(struct rproc *rproc, struct resource_table *table,
> -				int len,
> -				rproc_handle_resource_t handlers[RSC_LAST])
> +rproc_handle_resource(struct rproc *rproc, int len,
> +		      rproc_handle_resource_t handlers[RSC_LAST])
>  {
>  	struct device *dev = &rproc->dev;
>  	rproc_handle_resource_t handler;
>  	int ret = 0, i;
>  
> -	for (i = 0; i < table->num; i++) {
> -		int offset = table->offset[i];
> -		struct fw_rsc_hdr *hdr = (void *)table + offset;
> +	for (i = 0; i < rproc->rsc->num; i++) {
> +		int offset = rproc->rsc->offset[i];
> +		struct fw_rsc_hdr *hdr = (void *)rproc->rsc + offset;
>  		int avail = len - offset - sizeof(*hdr);
>  		void *rsc = (void *)hdr + sizeof(*hdr);
>  
> @@ -783,9 +782,13 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  {
>  	struct device *dev = &rproc->dev;
>  	const char *name = rproc->firmware;
> -	struct resource_table *table;
> +	struct rproc_vdev *rvdev;
> +	struct resource_table *table, *devmem_rsc, *tmp;
>  	int ret, tablesz;
>  
> +	if (!rproc->rsc)
> +		return -ENOMEM;
> +
>  	ret = rproc_fw_sanity_check(rproc, fw);
>  	if (ret)
>  		return ret;
> @@ -811,8 +814,17 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  		goto clean_up;
>  	}
>  
> +	/* Verify that resource table in loaded fw is unchanged */
> +	if (rproc->rsc_csum != ip_compute_csum(table, tablesz)) {
> +		dev_err(dev, "resource checksum failed, fw changed?\n");
> +		ret = -EINVAL;
> +		goto clean_up;
> +	}
> +
> +

Remove empty line?

>  	/* handle fw resources which are required to boot rproc */
> -	ret = rproc_handle_resource(rproc, table, tablesz, rproc_handle_rsc);
> +	ret = rproc_handle_resource(rproc, tablesz,
> +					rproc_handle_rsc);

This can fit in one line now :)

>  	if (ret) {
>  		dev_err(dev, "Failed to process resources: %d\n", ret);
>  		goto clean_up;
> @@ -825,6 +837,26 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  		goto clean_up;
>  	}
>  
> +	/* Get the resource table address in device memory */
> +	devmem_rsc = rproc_get_rsctab_addr(rproc, fw);
> +
> +	/* Copy the updated resource table to device memory */
> +	memcpy(devmem_rsc, rproc->rsc, tablesz);
> +
> +	/* Free the copy of the resource table */
> +	tmp = rproc->rsc;
> +	rproc->rsc = devmem_rsc;

This is also set a few lines below, and we can probably do without tmp
altogether.

> +	kfree(tmp);

If rproc_fw_boot is called more than once, kfree will try to free memory that
was not kmalloced, leading to a panic.

Instead of freeing the pointer here, it should be kept until rproc is
released, reverting rproc->rsc to it every time shutdown is called. It
can be freed when rproc is finally released.

> +
> +	/* Update the vdev rsc address */
> +	list_for_each_entry(rvdev, &rproc->rvdevs, node) {
> +		int offset = (void *)rvdev->rsc - (void *)tmp;
> +		rvdev->rsc = (void *)devmem_rsc + offset;
> +	}

I think it might be nicer and less error prone to hold the offsets to
the resources instead of pointers. This will require modifying
"remoteproc: Support virtio config space" accordingly, but will save the
trouble of updating pointers later on (both here, and on shutdown as
suggested above).

> +
> +	/* Other virtio drivers will see the rsc table in device memory */
> +	rproc->rsc = devmem_rsc;
> +
>  	/* power up the remote processor */
>  	ret = rproc->ops->start(rproc);
>  	if (ret) {
> @@ -866,14 +898,21 @@ static void rproc_fw_config_virtio(const struct firmware *fw, void *context)
>  	if (!table)
>  		goto out;
>  
> -	rproc->max_notifyid = 0;
> +	rproc->rsc_csum = ip_compute_csum(table, tablesz);

Doesn't matter much and any checksum would do, but given that this is not an IP
packet perhaps use something more generic (crc32 or similar)?
In any case, an appropriate dependency should to remoteproc's Kconfig.

>  
>  	/* count the numbe of notify-ids */
> -	ret = rproc_handle_resource(rproc, table, tablesz,
> +	rproc->max_notifyid = 0;
> +	rproc->rsc = table;

Instead of temporarily setting rproc->rsc here, why not just set it up before
figuring out the maximum notification id?

> +	ret = rproc_handle_resource(rproc, tablesz,
>  						rproc_handle_notifyid_rsc);
>  
> +	/* Copy resource table containing vdev config info */
> +	rproc->rsc = kmalloc(tablesz, GFP_KERNEL);
> +	if (rproc->rsc)
> +		memcpy(rproc->rsc, table, tablesz);
> +

If the kmalloc above returned NULL, we should probably bail out here.

>  	/* look for virtio devices and register them */
> -	ret = rproc_handle_resource(rproc, table, tablesz,
> +	ret = rproc_handle_resource(rproc, tablesz,
>  						rproc_handle_vdev_rsc);

This can fit in one line now

>  	if (ret)
>  		goto out;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index c0c363c..07deff4 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -41,6 +41,7 @@
>  #include <linux/virtio.h>
>  #include <linux/completion.h>
>  #include <linux/idr.h>
> +#include <asm/checksum.h>
>  
>  /**
>   * struct resource_table - firmware resource table header
> @@ -429,6 +430,8 @@ struct rproc {
>  	struct completion crash_comp;
>  	bool recovery_disabled;
>  	int max_notifyid;
> +	struct resource_table *rsc;
> +	__sum16 rsc_csum;
>  };
>  
>  /* we currently support only two vrings per rvdev */
> -- 
> 1.7.5.4
> 

Thanks,
Ido.
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