ARM: memremap: implement arch_memremap_wb()

The generic memremap() falls back to using ioremap_cache() to create
MEMREMAP_WB mappings if the requested region is not already covered
by the linear mapping, unless the architecture provides an implementation
of arch_memremap_wb().

Since ioremap_cache() is not appropriate on ARM to map memory with the
same attributes used for the linear mapping, implement arch_memremap_wb()
which does exactly that. Also, relax the WARN() check to allow MT_MEMORY_RW
mappings of pfn_valid() pages.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index f24967e8ff7f..ca6d8e8ca1f8 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -384,6 +384,11 @@ void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
 }
 EXPORT_SYMBOL(ioremap_wc);
 
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
+{
+	return (void *)phys_addr;
+}
+
 void __iounmap(volatile void __iomem *addr)
 {
 }