Currently, the memremap code serves MEMREMAP_WB mappings directly from
the kernel direct mapping, unless the region is in high memory, in which
case it falls back to using ioremap_cache(). However, the semantics of
ioremap_cache() are not unambiguously defined, and on ARM, it will
actually result in a mapping type that differs from the attributes used
for the linear mapping, and for this reason, the ioremap_cache() call
fails if the region is part of the memory managed by the kernel.
So instead, implement an optional hook 'arch_memremap_wb' whose default
implementation calls ioremap_cache() as before, but which can be
overridden by the architecture to do what is appropriate for it.
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
kernel/memremap.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 7a1b5c3ef14e..77c41648ba16 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -27,6 +27,13 @@ __weak void __iomem *ioremap_cache(resource_size_t offset,
unsigned long size)
}
#endif
+#ifndef arch_memremap_wb
+static void *arch_memremap_wb(resource_size_t offset, unsigned long size)
+{
+ return (__force void *)ioremap_cache(offset, size);
+}
+#endif
+
static void *try_ram_remap(resource_size_t offset, size_t size)
{
struct page *page = pfn_to_page(offset >> PAGE_SHIFT);
@@ -34,7 +41,7 @@ static void *try_ram_remap(resource_size_t offset, size_t
size)
/* In the simple case just return the existing linear address */
if (!PageHighMem(page))
return __va(offset);
- return NULL; /* fallback to ioremap_cache */
+ return arch_memremap_wb(offset, size);
}
/**
@@ -80,8 +87,6 @@ void *memremap(resource_size_t offset, size_t size, unsigned
long flags)
*/
if (is_ram == REGION_INTERSECTS)
addr = try_ram_remap(offset, size);
- if (!addr)
- addr = ioremap_cache(offset, size);
}
/*
--
2.5.0
