linux-kernel - [PATCH 7/9] staging: ion: Handle the memory mapping correctly on x86

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Date:	Fri, 29 Jan 2016 22:07:36 -0800
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	Vinil Cheeramvelil <vinil.cheeramvelil@...el.com>,
	Android Kernel Team <kernel-team@...roid.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	Laura Abbott <labbott@...hat.com>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Zhebin Jin <zhebin.jin@...el.com>,
	John Stultz <john.stultz@...aro.org>
Subject: [PATCH 7/9] staging: ion: Handle the memory mapping correctly on x86

From: Vinil Cheeramvelil <vinil.cheeramvelil@...el.com>

This patch modifies the ion page pool code to address
limitation in x86 PAT. When one physical page is mapped
to multiple virtual pages, the same cache policy
should be used. Add set_memory_wc/uc call to avoid aliases.
If not, all mappings will be cached(write back).

Cc: Android Kernel Team <kernel-team@...roid.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Laura Abbott <labbott@...hat.com>
Cc: Sumit Semwal <sumit.semwal@...aro.org>
Signed-off-by: Zhebin Jin <zhebin.jin@...el.com>
Signed-off-by: Vinil Cheeramvelil <vinil.cheeramvelil@...el.com>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/staging/android/ion/Kconfig           |  8 +++++++
 drivers/staging/android/ion/ion_page_pool.c   |  8 +++++++
 drivers/staging/android/ion/ion_priv.h        | 33 +++++++++++++++++++++++++++
 drivers/staging/android/ion/ion_system_heap.c |  6 +++--
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index 19c1572..a15ff29 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -40,3 +40,11 @@ config ION_HISI
 	  Choose this option if you wish to use ion on Hisilicon Platform.
 
 source "drivers/staging/android/ion/hisilicon/Kconfig"
+
+config ION_POOL_CACHE_POLICY
+	bool "Ion set page pool cache policy"
+	depends on ION
+	default y if X86
+	help
+	  Choose this option if need to explicity set cache policy of the
+	  pages in the page pool.
diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index fd7e23e..59ee2f8 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -30,6 +30,8 @@ static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 
 	if (!page)
 		return NULL;
+	ion_page_pool_alloc_set_cache_policy(pool, page);
+
 	ion_pages_sync_for_device(NULL, page, PAGE_SIZE << pool->order,
 						DMA_BIDIRECTIONAL);
 	return page;
@@ -38,6 +40,7 @@ static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 static void ion_page_pool_free_pages(struct ion_page_pool *pool,
 				     struct page *page)
 {
+	ion_page_pool_free_set_cache_policy(pool, page);
 	__free_pages(page, pool->order);
 }
 
@@ -103,6 +106,11 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 		ion_page_pool_free_pages(pool, page);
 }
 
+void ion_page_pool_free_immediate(struct ion_page_pool *pool, struct page *page)
+{
+	ion_page_pool_free_pages(pool, page);
+}
+
 static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
 {
 	int count = pool->low_count;
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
index 0239883..9a25ba6 100644
--- a/drivers/staging/android/ion/ion_priv.h
+++ b/drivers/staging/android/ion/ion_priv.h
@@ -26,6 +26,9 @@
 #include <linux/sched.h>
 #include <linux/shrinker.h>
 #include <linux/types.h>
+#ifdef CONFIG_ION_POOL_CACHE_POLICY
+#include <asm/cacheflush.h>
+#endif
 
 #include "ion.h"
 
@@ -381,6 +384,36 @@ struct ion_page_pool *ion_page_pool_create(gfp_t gfp_mask, unsigned int order);
 void ion_page_pool_destroy(struct ion_page_pool *);
 struct page *ion_page_pool_alloc(struct ion_page_pool *);
 void ion_page_pool_free(struct ion_page_pool *, struct page *);
+void ion_page_pool_free_immediate(struct ion_page_pool *, struct page *);
+
+#ifdef CONFIG_ION_POOL_CACHE_POLICY
+static inline void ion_page_pool_alloc_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){
+	void *va = page_address(page);
+
+	if (va)
+		set_memory_wc((unsigned long)va, 1 << pool->order);
+}
+
+static inline void ion_page_pool_free_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){
+	void *va = page_address(page);
+
+	if (va)
+		set_memory_wb((unsigned long)va, 1 << pool->order);
+}
+#else
+static inline void ion_page_pool_alloc_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){ }
+
+static inline void ion_page_pool_free_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){ }
+#endif
+
 
 /** ion_page_pool_shrink - shrinks the size of the memory cached in the pool
  * @pool:		the pool
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index d4c3e55..fa62cc4 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -85,8 +85,10 @@ static void free_buffer_page(struct ion_system_heap *heap,
 
 	if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) {
 		struct ion_page_pool *pool = heap->pools[order_to_index(order)];
-
-		ion_page_pool_free(pool, page);
+		if (buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)
+			ion_page_pool_free_immediate(pool, page);
+		else
+			ion_page_pool_free(pool, page);
 	} else {
 		__free_pages(page, order);
 	}
-- 
1.9.1