On Thu, Jan 10, 2019 at 02:09:39PM -0700, Khalid Aziz wrote:
> From: Juerg Haefliger <juerg.haefliger@xxxxxxxxxxxxx>
>
> If the page is unmapped by XPFO, a data cache flush results in a fatal
> page fault, so let's temporarily map the region, flush the cache, and then
> unmap it.
>
> v6: actually flush in the face of xpfo, and temporarily map the underlying
> memory so it can be flushed correctly
>
> CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Signed-off-by: Juerg Haefliger <juerg.haefliger@xxxxxxxxxxxxx>
> Signed-off-by: Tycho Andersen <tycho@xxxxxxxxxx>
> Signed-off-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
> ---
> arch/arm64/mm/flush.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
> index 30695a868107..f12f26b60319 100644
> --- a/arch/arm64/mm/flush.c
> +++ b/arch/arm64/mm/flush.c
> @@ -20,6 +20,7 @@
> #include <linux/export.h>
> #include <linux/mm.h>
> #include <linux/pagemap.h>
> +#include <linux/xpfo.h>
>
> #include <asm/cacheflush.h>
> #include <asm/cache.h>
> @@ -28,9 +29,15 @@
> void sync_icache_aliases(void *kaddr, unsigned long len)
> {
> unsigned long addr = (unsigned long)kaddr;
> + unsigned long num_pages = XPFO_NUM_PAGES(addr, len);
Is it possible that the 'len' is more than 32 pages? Or say 1000's
of pages? Which would blow away your stack.
> + void *mapping[num_pages];
>
> if (icache_is_aliasing()) {
> + xpfo_temp_map(kaddr, len, mapping,
> + sizeof(mapping[0]) * num_pages);
> __clean_dcache_area_pou(kaddr, len);
> + xpfo_temp_unmap(kaddr, len, mapping,
> + sizeof(mapping[0]) * num_pages);
> __flush_icache_all();
> } else {
> flush_icache_range(addr, addr + len);
> --
> 2.17.1
>
