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SubjectRe: [PATCH 2/2] MIPS: Flush highmem pages from dcache in __flush_icache_page

On 02/22/2016 07:09 PM, Paul Burton wrote:
> When a page is to be mapped executable for userspace, we can presume
> that the icache doesn't contain anything valid for its address range but
> we cannot be sure that its content has been written back from the dcache
> to L2 or memory further out. If the icache fills from those memories,
> ie. does not fill from the dcache, then we need to ensure that content
> has been flushed from the dcache. This was being done for lowmem pages
> but not for highmem pages. Fix this by mapping the page & flushing its
> content from the dcache in __flush_icache_page, before the page is
> provided to userland.
>

Reviewed-by: Lars Persson <larper@axis.com>

> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
>
> ---
>
> arch/mips/mm/cache.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
> index 3f159ca..734cb2f 100644
> --- a/arch/mips/mm/cache.c
> +++ b/arch/mips/mm/cache.c
> @@ -16,6 +16,7 @@
> #include <linux/mm.h>
>
> #include <asm/cacheflush.h>
> +#include <asm/highmem.h>
> #include <asm/processor.h>
> #include <asm/cpu.h>
> #include <asm/cpu-features.h>
> @@ -124,10 +125,14 @@ void __flush_icache_page(struct vm_area_struct *vma, struct page *page)
> unsigned long addr;
>
> if (PageHighMem(page))
> - return;
> + addr = (unsigned long)kmap_atomic(page);
> + else
> + addr = (unsigned long)page_address(page);
>
> - addr = (unsigned long) page_address(page);
> flush_data_cache_page(addr);
> +
> + if (PageHighMem(page))
> + __kunmap_atomic((void *)addr);
> }
> EXPORT_SYMBOL_GPL(__flush_icache_page);
>
>

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