The patch titled
Subject: memremap: don't modify flags
has been added to the -mm tree. Its filename is
memremap-dont-modify-flags.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/memremap-dont-modify-flags.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/memremap-dont-modify-flags.patch
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------------------------------------------------------
From: Brian Starkey <brian.starkey@xxxxxxx>
Subject: 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 <brian.starkey@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/memremap.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff -puN kernel/memremap.c~memremap-dont-modify-flags kernel/memremap.c
--- a/kernel/memremap.c~memremap-dont-modify-flags
+++ a/kernel/memremap.c
@@ -64,6 +64,9 @@ void *memremap(resource_size_t offset, s
IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
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, s
/* 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, s
}
/*
- * 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;
}
_
Patches currently in -mm which might be from brian.starkey@xxxxxxx are
memremap-dont-modify-flags.patch
memremap-add-memremap_wc-flag.patch
drivers-dma-coherent-use-memremap_wc-for-dma_memory_map.patch
drivers-dma-coherent-use-memset_io-for-dma_memory_io-mappings.patch
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