memremap: don't modify flags (cf61e2a1) · Commits · 戴 / test

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@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:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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;
		}

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