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Commit cf61e2a1 authored by Brian Starkey's avatar Brian Starkey Committed by Linus Torvalds
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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: default avatarBrian Starkey <brian.starkey@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 41b27154

kernel/memremap.c

+7 −7
Original line number Diff line number Diff line
@@ -64,6 +64,9 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags) 
				       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, 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;

}