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memremap: add arch specific hook for MEMREMAP_WB mappings 

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.

Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
This commit is contained in:
Ard Biesheuvel 2016-02-22 15:02:07 +01:00
parent 7769aea2a2
commit c269cba35b
1 changed files with 9 additions and 2 deletions
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11
kernel/memremap.c
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@ -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)
{
unsigned long pfn = PHYS_PFN(offset);
@ -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 (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)))
return __va(offset);
return NULL; /* fallback to ioremap_cache */
return NULL; /* fallback to arch_memremap_wb */
}
/**
@ -90,7 +97,7 @@ 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);
addr = arch_memremap_wb(offset, size);
}
/*