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authorArd Biesheuvel <ardb@kernel.org>2020-12-07 20:40:53 +0300
committerArd Biesheuvel <ardb@kernel.org>2020-12-09 10:37:27 +0300
commit4dbe44fb538c59a4adae5abfa9ded2f310250315 (patch)
treeda4f681ca5b596a899337141cf3cfadc185a98b9 /drivers/firmware
parent91c1c092f27da4164d55ca81e0a483108f8a3235 (diff)
downloadlinux-4dbe44fb538c59a4adae5abfa9ded2f310250315.tar.xz
efi: capsule: clean scatter-gather entries from the D-cache
Scatter-gather lists passed to UpdateCapsule() should be cleaned from the D-cache to ensure that they are visible to the CPU after a warm reboot before the MMU is enabled. On ARM and arm64 systems, this implies a D-cache clean by virtual address to the point of coherency. However, due to the fact that the firmware itself is not able to map physical addresses back to virtual addresses when running under the OS, this must be done by the caller. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efi/capsule.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c
index 43f6fe7bfe80..768430293669 100644
--- a/drivers/firmware/efi/capsule.c
+++ b/drivers/firmware/efi/capsule.c
@@ -12,6 +12,7 @@
#include <linux/highmem.h>
#include <linux/efi.h>
#include <linux/vmalloc.h>
+#include <asm/efi.h>
#include <asm/io.h>
typedef struct {
@@ -265,6 +266,17 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages)
else
sglist[j].data = page_to_phys(sg_pages[i + 1]);
+#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
+ /*
+ * At runtime, the firmware has no way to find out where the
+ * sglist elements are mapped, if they are mapped in the first
+ * place. Therefore, on architectures that can only perform
+ * cache maintenance by virtual address, the firmware is unable
+ * to perform this maintenance, and so it is up to the OS to do
+ * it instead.
+ */
+ efi_capsule_flush_cache_range(sglist, PAGE_SIZE);
+#endif
kunmap_atomic(sglist);
}