[PATCH v6 07/11] arm64/mm, xpfo: temporarily map dcache regions

Tycho Andersen tycho at docker.com
Thu Sep 7 10:36:05 PDT 2017

From: Juerg Haefliger <juerg.haefliger at canonical.com>

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 at lists.infradead.org
Signed-off-by: Juerg Haefliger <juerg.haefliger at canonical.com>
Signed-off-by: Tycho Andersen <tycho at docker.com>
 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 21a8d828cbf4..e335e3fd4fca 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);
+	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);
 	} else {
 		flush_icache_range(addr, addr + len);

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