linux-kernel - [PATCH v4 2/5] misc: fastrpc: Add CRC support for remote buffers

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Date:   Tue, 17 Oct 2023 14:56:36 +0530
From:   Ekansh Gupta <quic_ekangupt@...cinc.com>
To:     <srinivas.kandagatla@...aro.org>, <linux-arm-msm@...r.kernel.org>
CC:     Ekansh Gupta <quic_ekangupt@...cinc.com>,
        <ekangupt@....qualcomm.com>, <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>, <fastrpc.upstream@....qualcomm.com>
Subject: [PATCH v4 2/5] misc: fastrpc: Add CRC support for remote buffers

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>
---
 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 e392e2a..825ff91 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;
@@ -1066,6 +1067,7 @@ 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);
@@ -1073,7 +1075,8 @@ 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]) {
@@ -1097,6 +1100,10 @@ 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;
 }
 
@@ -1721,6 +1728,7 @@ static int fastrpc_multimode_invoke(struct fastrpc_user *fl, char __user *argp)
 
 	switch (invoke.req) {
 	case FASTRPC_INVOKE:
+	case FASTRPC_INVOKE_ENHANCED:
 		/* nscalars is truncated here to max supported value */
 		if (copy_from_user(&einv, (void __user *)(uintptr_t)invoke.invparam,
 				   invoke.size))
-- 
2.7.4