linux-kernel - [PATCH 3/8] misc: fastrpc: make sure memory read and writes are visible

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Date:   Thu,  7 Mar 2019 10:12:24 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     gregkh@...uxfoundation.org, arnd@...db.de
Cc:     linux-kernel@...r.kernel.org, bjorn.andersson@...aro.org,
        bkumar@....qualcomm.com, linux-arm-msm@...r.kernel.org,
        ktadakam@....qualcomm.com,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 3/8] misc: fastrpc: make sure memory read and writes are visible

dma_alloc_coherent buffers could have writes queued in store buffers so
commit them before sending buffer to DSP using correct dma barriers.
Same with vice-versa.

Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/misc/fastrpc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 8fbcc607a77e..753d62ceb1fb 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -792,6 +792,9 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 		if (err)
 			goto bail;
 	}
+
+	/* make sure that all CPU memory writes are seen by DSP */
+	dma_wmb();
 	/* Send invoke buffer to remote dsp */
 	err = fastrpc_invoke_send(fl->sctx, ctx, kernel, handle);
 	if (err)
@@ -808,6 +811,8 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 		goto bail;
 
 	if (ctx->nscalars) {
+		/* make sure that all memory writes by DSP are seen by CPU */
+		dma_rmb();
 		/* populate all the output buffers with results */
 		err = fastrpc_put_args(ctx, kernel);
 		if (err)
-- 
2.21.0