[PATCH v2 09/10] ARM: early-mmu: don't cache/prefetch OPTEE_SIZE bytes from end of memory

[Ahmad Fatoum]

OPTEE_SIZE is always defined in <asm-generic/memory_layout.h> either as
as CONFIG_OPTEE_SIZE or as 0 if the option is undefined.

There is never a reason to map the last OPTEE_SIZE bytes in the initial
memory as cached and executable:

 - OPTEE_SIZE == 0: no change
 - OPTEE_SIZE != 0 && CONFIG_PBL_OPTEE=y: cache must not be enabled for
   the region to avoid speculation
 - OPTEE_SIZE != 0 && CONFIG_BOOTM_OPTEE=y: we won't use this region
   for anything between MMU early init and normal init, so no harm
   in disabling caches.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/arm/cpu/start.c      | 2 +-
 arch/arm/cpu/uncompress.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 5861c15d43df..672f26e0063c 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -171,7 +171,7 @@ __noreturn __no_sanitize_address void barebox_non_pbl_start(unsigned long membas
 		} else {
 			pr_debug("enabling MMU, ttb @ 0x%08lx\n", ttb);
 			arm_early_mmu_cache_invalidate();
-			mmu_early_enable(membase, memsize, ttb);
+			mmu_early_enable(membase, memsize - OPTEE_SIZE, ttb);
 		}
 	}
 
diff --git a/arch/arm/cpu/uncompress.c b/arch/arm/cpu/uncompress.c
index 2250b8ccd375..537ee63229d7 100644
--- a/arch/arm/cpu/uncompress.c
+++ b/arch/arm/cpu/uncompress.c
@@ -84,7 +84,7 @@ void __noreturn barebox_pbl_start(unsigned long membase, unsigned long memsize,
 	if (IS_ENABLED(CONFIG_MMU_EARLY)) {
 		unsigned long ttb = arm_mem_ttb(membase, endmem);
 		pr_debug("enabling MMU, ttb @ 0x%08lx\n", ttb);
-		mmu_early_enable(membase, memsize, ttb);
+		mmu_early_enable(membase, memsize - OPTEE_SIZE, ttb);
 	}
 
 	free_mem_ptr = arm_mem_early_malloc(membase, endmem);
-- 
2.30.2