ARM: add dma coherent region reporting via procfs

Add a new seqfile for reporting coherent DMA allocations.  This contains
the address range, size and the function which was used to allocate
each region, allowing these allocations to be viewed in much the same
way as /proc/vmallocinfo.

The DMA coherent region has limited space, so this allows allocation
failures to be viewed, as well as finding out how much space is being
used.

Make sure this file is only readable by root - same as vmallocinfo - to
prevent information leakage.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 13 insertions, 7 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 1aa664a1999f..db23ae4aaaab 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -214,7 +214,8 @@ static int __init consistent_init(void)
 core_initcall(consistent_init);
 
 static void *
-__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
+__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
+        const void *caller)
 {
         struct arm_vmregion *c;
         size_t align;
@@ -241,7 +242,7 @@ __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
          * Allocate a virtual address in the consistent mapping region.
          */
         c = arm_vmregion_alloc(&consistent_head, align, size,
-                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
+                            gfp & ~(__GFP_DMA | __GFP_HIGHMEM), caller);
         if (c) {
                 pte_t *pte;
                 int idx = CONSISTENT_PTE_INDEX(c->vm_start);
@@ -320,14 +321,14 @@ static void __dma_free_remap(void *cpu_addr, size_t size)
 
 #else   /* !CONFIG_MMU */
 
-#define __dma_alloc_remap(page, size, gfp, prot)        page_address(page)
+#define __dma_alloc_remap(page, size, gfp, prot, c)     page_address(page)
 #define __dma_free_remap(addr, size)                    do { } while (0)
 
 #endif  /* CONFIG_MMU */
 
 static void *
 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
-            pgprot_t prot)
+            pgprot_t prot, const void *caller)
 {
         struct page *page;
         void *addr;
@@ -349,7 +350,7 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
                 return NULL;
 
         if (!arch_is_coherent())
-                addr = __dma_alloc_remap(page, size, gfp, prot);
+                addr = __dma_alloc_remap(page, size, gfp, prot, caller);
         else
                 addr = page_address(page);
 
@@ -374,7 +375,8 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gf
                 return memory;
 
         return __dma_alloc(dev, size, handle, gfp,
-                           pgprot_dmacoherent(pgprot_kernel));
+                           pgprot_dmacoherent(pgprot_kernel),
+                           __builtin_return_address(0));
 }
 EXPORT_SYMBOL(dma_alloc_coherent);
 
@@ -386,7 +388,8 @@ void *
 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 {
         return __dma_alloc(dev, size, handle, gfp,
-                           pgprot_writecombine(pgprot_kernel));
+                           pgprot_writecombine(pgprot_kernel),
+                           __builtin_return_address(0));
 }
 EXPORT_SYMBOL(dma_alloc_writecombine);
 
@@ -723,6 +726,9 @@ EXPORT_SYMBOL(dma_set_mask);
 
 static int __init dma_debug_do_init(void)
 {
+#ifdef CONFIG_MMU
+        arm_vmregion_create_proc("dma-mappings", &consistent_head);
+#endif
         dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
         return 0;
 }