linux-kernel - Re: [PATCH v7 2/5] misc: fastrpc: Add CRC support for remote buffers

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Date:   Fri, 24 Nov 2023 13:26:56 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Ekansh Gupta <quic_ekangupt@...cinc.com>,
        linux-arm-msm@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/5] misc: fastrpc: Add CRC support for remote buffers



On 21/11/2023 09:48, Ekansh Gupta wrote:
> CRC check for input and output argument helps in ensuring data
> consistency over a remote call. If user intends to enable CRC check,
> first local user CRC is calculated at user end and a CRC buffer is
> passed to DSP to capture remote CRC values. DSP is expected to
> write to the remote CRC buffer which is then compared at user level
> with the local CRC values.
> 
> Signed-off-by: Ekansh Gupta <quic_ekangupt@...cinc.com>
> ---
> Changes in v7:
>    - Rebase the patch to latest kernel version
> 
>   drivers/misc/fastrpc.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 265e34f53c4e..55f126c779cb 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -611,6 +611,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
>   	/* Released in fastrpc_context_put() */
>   	fastrpc_channel_ctx_get(cctx);
>   
> +	ctx->crc = (u32 *)(uintptr_t)invoke->crc;
>   	ctx->sc = sc;
>   	ctx->retval = -1;
>   	ctx->pid = current->pid;
> @@ -1067,6 +1068,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
>   	struct fastrpc_invoke_buf *list;
>   	struct fastrpc_phy_page *pages;
>   	u64 *fdlist;
> +	u32 *crclist;
>   	int i, inbufs, outbufs, handles;
>   
>   	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
> @@ -1074,7 +1076,8 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
>   	handles = REMOTE_SCALARS_INHANDLES(ctx->sc) + REMOTE_SCALARS_OUTHANDLES(ctx->sc);
>   	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>   	pages = fastrpc_phy_page_start(list, ctx->nscalars);
> -	fdlist = (uint64_t *)(pages + inbufs + outbufs + handles);
> +	fdlist = (u64 *)(pages + inbufs + outbufs + handles);
> +	crclist = (u32 *)(fdlist + FASTRPC_MAX_FDLIST);
>   
>   	for (i = inbufs; i < ctx->nbufs; ++i) {
>   		if (!ctx->maps[i]) {
> @@ -1099,6 +1102,10 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
>   			fastrpc_map_put(mmap);
>   	}
>   
> +	if (ctx->crc && crclist && rpra) {
> +		if (copy_to_user((void __user *)ctx->crc, crclist, FASTRPC_MAX_CRCLIST * sizeof(u32)))
> +			return -EFAULT;
> +	}
>   	return 0;
>   }
>   
> @@ -1719,6 +1726,7 @@ static int fastrpc_multimode_invoke(struct fastrpc_user *fl, char __user *argp)
>   
>   	switch (invoke.req) {
>   	case FASTRPC_INVOKE:
> +	case FASTRPC_INVOKE_ENHANCED:

Isn't this change part of 1/5 patch?



>   		/* nscalars is truncated here to max supported value */
>   		if (copy_from_user(&einv, (void __user *)(uintptr_t)invoke.invparam,
>   				   invoke.size))