drm/msm: use kvmalloc for ring data in gpu crashstate

The current implementation of ascii85_encode() does not copy the encoded buffer 'z' to the output buffer in case the input is zero. This patch simply adds this missing piece. This makes it easier to use this function to encode large buffers.

Signed-off-by Sharat Masetty <[email protected]>

---
 include/linux/ascii85.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

include/linux/ascii85.h +6 -2

index 4cc4020..00646fc 100644
@@ -23,8 +23,12 @@
 {
 	int i;
 
-	if (in == 0)
-		return "z";
+	if (in == 0) {
+		out[0] = 'z';
+		out[1] = '\0';
+
+		return out;
+	}
 
 	out[5] = '\0';
 	for (i = 5; i--; ) {

Signature · 1 line

1.9.1

The ring substructure in msm_gpu_state is an extension of msm_gpu_state_bo, so this patch changes the ring structure to reuse the msm_gpu_state_bo as a base class, instead of redefining the required variables.

Signed-off-by Sharat Masetty <[email protected]>

---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 20 +++++++++++---------
 drivers/gpu/drm/msm/msm_gpu.h           |  4 +---
 2 files changed, 12 insertions(+), 12 deletions(-)

drivers/gpu/drm/msm/adreno/adreno_gpu.c +1 -1

index 6ebe842..bbf8d3e 100644
@@ -383,7 +383,7 @@ int adreno_gpu_state_get(struct msm_gpu *gpu, struct msm_gpu_state *state)
 		int size = 0, j;
 
 		state->ring[i].fence = gpu->rb[i]->memptrs->fence;
-		state->ring[i].iova = gpu->rb[i]->iova;
+		state->ring[i].bo.iova = gpu->rb[i]->iova;
 		state->ring[i].seqno = gpu->rb[i]->seqno;
 		state->ring[i].rptr = get_rptr(adreno_gpu, gpu->rb[i]);
 		state->ring[i].wptr = get_wptr(gpu->rb[i]);

@@ -397,10 +397,12 @@ int adreno_gpu_state_get(struct msm_gpu *gpu, struct msm_gpu_state *state)
 				size = j + 1;
 
 		if (size) {

drivers/gpu/drm/msm/adreno/adreno_gpu.c +4 -4

 			}
 		}
 	}

@@ -440,7 +442,7 @@ void adreno_gpu_state_destroy(struct msm_gpu_state *state)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(state->ring); i++)
-		kvfree(state->ring[i].data);
+		kvfree(state->ring[i].bo.data);
 
 	for (i = 0; state->bos && i < state->nr_bos; i++)
 		kvfree(state->bos[i].data);

@@ -522,15 +524,15 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
 
 	for (i = 0; i < gpu->nr_rings; i++) {
 		drm_printf(p, "  - id: %d\n", i);
-		drm_printf(p, "    iova: 0x%016llx\n", state->ring[i].iova);
+		drm_printf(p, "    iova: 0x%016llx\n", state->ring[i].bo.iova);
 		drm_printf(p, "    last-fence: %d\n", state->ring[i].seqno);
 		drm_printf(p, "    retired-fence: %d\n", state->ring[i].fence);
 		drm_printf(p, "    rptr: %d\n", state->ring[i].rptr);
 		drm_printf(p, "    wptr: %d\n", state->ring[i].wptr);
 		drm_printf(p, "    size: %d\n", MSM_GPU_RINGBUFFER_SZ);
 
-		adreno_show_object(p, state->ring[i].data,
-			state->ring[i].data_size);
+		adreno_show_object(p, state->ring[i].bo.data,
+			state->ring[i].bo.size);
 	}
 
 	if (state->bos) {

drivers/gpu/drm/msm/msm_gpu.h +1 -3

index 7dc775f..a3a6371 100644
@@ -198,13 +198,11 @@ struct msm_gpu_state {
 	struct timeval time;
 
 	struct {
-		u64 iova;
 		u32 fence;
 		u32 seqno;
 		u32 rptr;
 		u32 wptr;
-		void *data;
-		int data_size;
+		struct msm_gpu_state_bo bo;
 	} ring[MSM_GPU_MAX_RINGS];
 
 	int nr_registers;

Signature · 1 line

1.9.1

The ringbuffer data to capture at crashtime can end up being large sometimes, and the size can vary from being less than a page to the full size of 32KB. So use the kvmalloc variant that perfectly fits the bill.

Signed-off-by Sharat Masetty <[email protected]>

---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/gpu/drm/msm/adreno/adreno_gpu.c +2 -2

index d88d00d..6ebe842 100644
@@ -397,7 +397,7 @@ int adreno_gpu_state_get(struct msm_gpu *gpu, struct msm_gpu_state *state)
 				size = j + 1;
 
 		if (size) {
-			state->ring[i].data = kmalloc(size << 2, GFP_KERNEL);
+			state->ring[i].data = kvmalloc(size << 2, GFP_KERNEL);
 			if (state->ring[i].data) {
 				memcpy(state->ring[i].data, gpu->rb[i]->start, size << 2);
 				state->ring[i].data_size = size << 2;

@@ -440,7 +440,7 @@ void adreno_gpu_state_destroy(struct msm_gpu_state *state)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(state->ring); i++)
-		kfree(state->ring[i].data);
+		kvfree(state->ring[i].data);
 
 	for (i = 0; state->bos && i < state->nr_bos; i++)
 		kvfree(state->bos[i].data);

Signature · 1 line

1.9.1

When the userspace tries to read the crashstate dump, the read side implementation in the driver currently ascii85 encodes all the binary buffers and it does this each time the read system call is called. A userspace tool like cat typically does a page by page read and the number of read calls depends on the size of the data captured by the driver. This is certainly not desirable and does not scale well with large captures.

This patch encodes the buffer only once in the read path. With this there is an immediate >10X speed improvement in crashstate save time.

Signed-off-by Sharat Masetty <[email protected]>

---
Changes from v1:
Addressed comments from Jordan Crouse

 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 80 ++++++++++++++++++++++++---------
 drivers/gpu/drm/msm/msm_gpu.h           |  1 +
 2 files changed, 60 insertions(+), 21 deletions(-)

drivers/gpu/drm/msm/adreno/adreno_gpu.c +59 -21

index bbf8d3e..7749967 100644
@@ -441,11 +441,15 @@ void adreno_gpu_state_destroy(struct msm_gpu_state *state)
 {
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(state->ring); i++)
+	for (i = 0; i < ARRAY_SIZE(state->ring); i++) {
 		kvfree(state->ring[i].bo.data);
+		kvfree(state->ring[i].bo.encoded);
+	}
 
-	for (i = 0; state->bos && i < state->nr_bos; i++)
+	for (i = 0; state->bos && i < state->nr_bos; i++) {
 		kvfree(state->bos[i].data);
+		kvfree(state->bos[i].encoded);
+	}
 
 	kfree(state->bos);
 	kfree(state->comm);

@@ -472,34 +476,70 @@ int adreno_gpu_state_put(struct msm_gpu_state *state)
 
 #if defined(CONFIG_DEBUG_FS) || defined(CONFIG_DEV_COREDUMP)
 
-static void adreno_show_object(struct drm_printer *p, u32 *ptr, int len)
+static char *adreno_gpu_ascii85_encode(u32 *src, size_t len)
 {
-	char out[ASCII85_BUFSZ];
-	long l, datalen, i;
+	void *buf;
+	size_t buf_itr = 0;
+	long i, l;
 
-	if (!ptr || !len)
-		return;
+	if (!len)
+		return NULL;
+
+	l = ascii85_encode_len(len);
 
 	/*
-	 * Only dump the non-zero part of the buffer - rarely will any data
-	 * completely fill the entire allocated size of the buffer
+	 * ascii85 outputs either a 5 byte string or a 1 byte string. So we
+	 * account for the worst case of 5 bytes per dword plus the 1 for '\0'
 	 */
-	for (datalen = 0, i = 0; i < len >> 2; i++) {
-		if (ptr[i])
-			datalen = (i << 2) + 1;
+	buf = kvmalloc((l * 5) + 1, GFP_KERNEL);
+	if (!buf)
+		return NULL;
+
+	for (i = 0; i < l; i++) {
+		ascii85_encode(src[i], buf + buf_itr);
+
+		if (src[i] == 0)
+			buf_itr += 1;
+		else
+			buf_itr += 5;
 	}
 
-	/* Skip printing the object if it is empty */
-	if (datalen == 0)
+	return buf;
+}
+
+static void adreno_show_object(struct drm_printer *p,
+		struct msm_gpu_state_bo *bo)
+{
+	if ((!bo->data && !bo->encoded) || !bo->size)
 		return;
 
-	l = ascii85_encode_len(datalen);
+	if (!bo->encoded) {
+		long datalen, i;
+		u32 *buf = bo->data;
+
+		/*
+		 * Only dump the non-zero part of the buffer - rarely will
+		 * any data completely fill the entire allocated size of
+		 * the buffer.
+		 */
+		for (datalen = 0, i = 0; i < (bo->size) >> 2; i++) {
+			if (buf[i])
+				datalen = ((i + 1) << 2);
+		}
+
+		bo->encoded = adreno_gpu_ascii85_encode(buf, datalen);
+
+		kvfree(bo->data);
+		bo->data = NULL;
+
+		if (!bo->encoded)
+			return;
+	}
 
 	drm_puts(p, "    data: !!ascii85 |\n");
 	drm_puts(p, "     ");
 
-	for (i = 0; i < l; i++)
-		drm_puts(p, ascii85_encode(ptr[i], out));
+	drm_puts(p, bo->encoded);
 
 	drm_puts(p, "\n");
 }

@@ -531,8 +571,7 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
 		drm_printf(p, "    wptr: %d\n", state->ring[i].wptr);
 		drm_printf(p, "    size: %d\n", MSM_GPU_RINGBUFFER_SZ);
 
-		adreno_show_object(p, state->ring[i].bo.data,
-			state->ring[i].bo.size);
+		adreno_show_object(p, &(state->ring[i].bo));
 	}
 
 	if (state->bos) {

@@ -543,8 +582,7 @@ void adreno_show(struct msm_gpu *gpu, struct msm_gpu_state *state,
 				state->bos[i].iova);
 			drm_printf(p, "    size: %zd\n", state->bos[i].size);
 
-			adreno_show_object(p, state->bos[i].data,
-				state->bos[i].size);
+			adreno_show_object(p, &(state->bos[i]));
 		}
 	}
 

drivers/gpu/drm/msm/msm_gpu.h +1 -1

index a3a6371..737bf45 100644
@@ -191,6 +191,7 @@ struct msm_gpu_state_bo {
 	u64 iova;
 	size_t size;
 	void *data;
+	char *encoded;
 };
 
 struct msm_gpu_state {
--

1.9.1