path: root/kernel
diff options
authorBrian Starkey <>2016-03-22 14:27:57 -0700
committerLinus Torvalds <>2016-03-22 15:36:02 -0700
commitcf61e2a1487d833e4748dead4096584de70bf742 (patch)
tree311f4ff6e83253a858d583face5d5af9aedb4149 /kernel
parent41b27154874b3a40d6673052d08c8e9fd0c6404f (diff)
memremap: don't modify flags
These patches implement a MEMREMAP_WC flag for memremap(), which can be used to obtain writecombine mappings. This is then used for setting up dma_coherent_mem regions which use the DMA_MEMORY_MAP flag. The motivation is to fix an alignment fault on arm64, and the suggestion to implement MEMREMAP_WC for this case was made at [1]. That particular issue is handled in patch 4, which makes sure that the appropriate memset function is used when zeroing allocations mapped as IO memory. This patch (of 4): Don't modify the flags input argument to memremap(). MEMREMAP_WB is already a special case so we can check for it directly instead of clearing flag bits in each mapper. Signed-off-by: Brian Starkey <> Cc: Catalin Marinas <> Cc: Dan Williams <> Cc: Greg Kroah-Hartman <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'kernel')
1 files changed, 7 insertions, 7 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 584febd13e2e..e5e685e6ff2a 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -64,6 +64,9 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
void *addr = NULL;
+ if (!flags)
+ return NULL;
if (is_ram == REGION_MIXED) {
WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
&offset, (unsigned long) size);
@@ -72,7 +75,6 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
/* Try all mapping types requested until one returns non-NULL */
if (flags & MEMREMAP_WB) {
- flags &= ~MEMREMAP_WB;
* MEMREMAP_WB is special in that it can be satisifed
* from the direct map. Some archs depend on the
@@ -86,21 +88,19 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
- * If we don't have a mapping yet and more request flags are
- * pending then we will be attempting to establish a new virtual
+ * If we don't have a mapping yet and other request flags are
+ * present then we will be attempting to establish a new virtual
* address mapping. Enforce that this mapping is not aliasing
* System RAM.
- if (!addr && is_ram == REGION_INTERSECTS && flags) {
+ if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
&offset, (unsigned long) size);
return NULL;
- if (!addr && (flags & MEMREMAP_WT)) {
- flags &= ~MEMREMAP_WT;
+ if (!addr && (flags & MEMREMAP_WT))
addr = ioremap_wt(offset, size);
- }
return addr;