From 5ffb9e5b7a80805f6e6c504cdd1d70d6411b51ab Mon Sep 17 00:00:00 2001
From: Jordan Crouse <jcrouse@codeaurora.org>
Date: Wed, 11 Sep 2019 08:32:15 -0600
Subject: [PATCH] msm: kgsl: Make the "scratch" global buffer use a random GPU
 address

Select a random global GPU address for the "scratch" buffer that is used
by the ringbuffer for various tasks.

Change-Id: Ic0dedbaddda71dbf9cb2adab3c6c33a24d6a604c
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Harshitha Sai Neelati <hsaine@codeaurora.org>
---
 drivers/gpu/msm/adreno_ringbuffer.c |  2 +-
 drivers/gpu/msm/kgsl.h              |  4 +++-
 drivers/gpu/msm/kgsl_iommu.c        | 25 +++++++++++++++++++++----
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/msm/adreno_ringbuffer.c b/drivers/gpu/msm/adreno_ringbuffer.c
index 8a3028c7b670..3a3777823013 100644
--- a/drivers/gpu/msm/adreno_ringbuffer.c
+++ b/drivers/gpu/msm/adreno_ringbuffer.c
@@ -277,7 +277,7 @@ int adreno_ringbuffer_probe(struct adreno_device *adreno_dev, bool nopreempt)
 
 	if (!adreno_is_a3xx(adreno_dev)) {
 		status = kgsl_allocate_global(device, &device->scratch,
-				PAGE_SIZE, 0, 0, "scratch");
+				PAGE_SIZE, 0, KGSL_MEMDESC_RANDOM, "scratch");
 		if (status != 0)
 			return status;
 	}
diff --git a/drivers/gpu/msm/kgsl.h b/drivers/gpu/msm/kgsl.h
index a486d9a86f9d..6b8ef82d340f 100644
--- a/drivers/gpu/msm/kgsl.h
+++ b/drivers/gpu/msm/kgsl.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2008-2016, 2018, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2008-2016,2018-2019, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -189,6 +189,8 @@ struct kgsl_memdesc_ops {
 #define KGSL_MEMDESC_TZ_LOCKED BIT(7)
 /* The memdesc is allocated through contiguous memory */
 #define KGSL_MEMDESC_CONTIG BIT(8)
+/* For global buffers, randomly assign an address from the region */
+#define KGSL_MEMDESC_RANDOM BIT(9)
 
 /**
  * struct kgsl_memdesc - GPU memory object descriptor
diff --git a/drivers/gpu/msm/kgsl_iommu.c b/drivers/gpu/msm/kgsl_iommu.c
index 30f7c9543e38..ffab5423d694 100644
--- a/drivers/gpu/msm/kgsl_iommu.c
+++ b/drivers/gpu/msm/kgsl_iommu.c
@@ -20,6 +20,7 @@
 #include <linux/msm_kgsl.h>
 #include <linux/ratelimit.h>
 #include <linux/of_platform.h>
+#include <linux/random.h>
 #include <soc/qcom/scm.h>
 #include <soc/qcom/secure_buffer.h>
 #include <stddef.h>
@@ -198,7 +199,7 @@ static void kgsl_iommu_remove_global(struct kgsl_mmu *mmu,
 static void kgsl_iommu_add_global(struct kgsl_mmu *mmu,
 		struct kgsl_memdesc *memdesc, const char *name)
 {
-	int bit;
+	u32 bit, start = 0;
 	u64 size = kgsl_memdesc_footprint(memdesc);
 
 	if (memdesc->gpuaddr != 0)
@@ -207,10 +208,26 @@ static void kgsl_iommu_add_global(struct kgsl_mmu *mmu,
 	if (WARN_ON(global_pt_count >= GLOBAL_PT_ENTRIES))
 		return;
 
-	bit = bitmap_find_next_zero_area(global_map, GLOBAL_MAP_PAGES,
-		0, size >> PAGE_SHIFT, 0);
+	if (WARN_ON(size > KGSL_IOMMU_GLOBAL_MEM_SIZE))
+		return;
 
-	if (WARN_ON(bit >= GLOBAL_MAP_PAGES))
+	if (memdesc->priv & KGSL_MEMDESC_RANDOM) {
+		u32 range = GLOBAL_MAP_PAGES - (size >> PAGE_SHIFT);
+
+		start = get_random_int() % range;
+	}
+
+	while (start >= 0) {
+		bit = bitmap_find_next_zero_area(global_map, GLOBAL_MAP_PAGES,
+			start, size >> PAGE_SHIFT, 0);
+
+		if (bit < GLOBAL_MAP_PAGES)
+			break;
+
+		start--;
+	}
+
+	if (WARN_ON(start < 0))
 		return;
 
 	memdesc->gpuaddr =