[PATCH v3] ARM: zImage: perform cache maintenance after relocating code (was: ARM: zImage: add DSB and ISB barriers after relocating code)

[Marc Carino]

The zImage loader will relocate the kernel image if it determines that
decompression will overwrite its current location. Since the act of relocation
is a form of code self-modification, we need to ensure that the CPU fetches
the updated instruction stream.

Instead of conditionally executing cache maintenance, this commit ensures that
cache maintenance is performed in all cases. Besides ensuring coherency with
the caches and main memory, performing cache maintenance ensures that any
potentially stale instructions are flushed from the instruction pipeline.

Signed-off-by: Marc Carino <marc.ceeeee at gmail.com>
---
 arch/arm/boot/compressed/head.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 3a8b32d..8a39054 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -395,8 +395,7 @@ dtb_check_done:
 		add	sp, sp, r6
 #endif
 
-		tst	r4, #1
-		bleq	cache_clean_flush
+		bl	cache_clean_flush
 
 		adr	r0, BSYM(restart)
 		add	r0, r0, r6
-- 
1.8.1.3