[PATCH 1/2] ARM startup: invalidate I-cache before jumping to relocated binary

[PATCH 1/2] ARM startup: invalidate I-cache before jumping to relocated binary

[Sascha Hauer]

barebox can startup with I-cache enabled, so to be on the safe
side we should invalidate the I-cache before jumping to a binary
we just copied in place.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/cpu/start.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index ede8fd1..0fcc950 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -135,6 +135,9 @@ void __naked __section(.text_ll_return) board_init_lowlevel_return(void)
 	/* clear bss */
 	memset(__bss_start, 0, __bss_stop - __bss_start);
 
+	/* flush I-cache before jumping to the copied binary */
+	__asm__ __volatile__("mcr p15, 0, %0, c7, c5, 0" : : "r" (0));
+
 	/* call start_barebox with its absolute address */
 	r = (unsigned int)&start_barebox;
 	__asm__ __volatile__("mov pc, %0" : : "r"(r));
-- 
1.7.10


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[PATCH 2/2] ARM startup: Do call __mmu_cache_flush during startup

[Sascha Hauer]

Traditionally we call __mmu_cache_flush in early startup. There
is a problem with armv7 and hierarchical caches though, on these
systems __mmu_cache_flush uses the stack. Appearantly this was
seldomly a problem, because most of these systems have a ROM
bootloader which sets up some stack, but on a special i.MX6 system
this failed badly. We should not have to flush caches here. Every
sane system should pass control to the bootloader without stale
entries in the caches *), so it should be a safe assumption that the
cache flush can be removed.

Since __mmu_cache_flush is not called from early code anymore we can
also move it to the regular text section.

Be brave and give it a try.

*) omap3 seems to be a exception to this, but this has a cache flush
in arch_init_lowlevel already

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/cpu/cache-armv4.S |    1 -
 arch/arm/cpu/cache-armv5.S |    1 -
 arch/arm/cpu/cache-armv6.S |    1 -
 arch/arm/cpu/cache-armv7.S |    1 -
 arch/arm/cpu/start.c       |    6 ------
 5 files changed, 10 deletions(-)

diff --git a/arch/arm/cpu/cache-armv4.S b/arch/arm/cpu/cache-armv4.S
index fc53653..6d03565 100644
--- a/arch/arm/cpu/cache-armv4.S
+++ b/arch/arm/cpu/cache-armv4.S
@@ -42,7 +42,6 @@ ENTRY(__mmu_cache_off)
 		mov	pc, lr
 ENDPROC(__mmu_cache_off)
 
-__BARE_INIT
 ENTRY(__mmu_cache_flush)
 		mrc	p15, 0, r6, c0, c0	@ get processor ID
 		mov	r2, #64*1024		@ default: 32K dcache size (*2)
diff --git a/arch/arm/cpu/cache-armv5.S b/arch/arm/cpu/cache-armv5.S
index d870e6b..a1193a6 100644
--- a/arch/arm/cpu/cache-armv5.S
+++ b/arch/arm/cpu/cache-armv5.S
@@ -42,7 +42,6 @@ ENTRY(__mmu_cache_off)
 		mov	pc, lr
 ENDPROC(__mmu_cache_off)
 
-__BARE_INIT
 ENTRY(__mmu_cache_flush)
 1:		mrc	p15, 0, r15, c7, c14, 3	@ test,clean,invalidate D cache
 		bne	1b
diff --git a/arch/arm/cpu/cache-armv6.S b/arch/arm/cpu/cache-armv6.S
index 9de76da..335bac2 100644
--- a/arch/arm/cpu/cache-armv6.S
+++ b/arch/arm/cpu/cache-armv6.S
@@ -44,7 +44,6 @@ ENTRY(__mmu_cache_off)
 #endif
 		mov	pc, lr
 
-__BARE_INIT
 ENTRY(__mmu_cache_flush)
 		mov	r1, #0
 		mcr	p15, 0, r1, c7, c14, 0	@ clean+invalidate D
diff --git a/arch/arm/cpu/cache-armv7.S b/arch/arm/cpu/cache-armv7.S
index 416498d..28a6315 100644
--- a/arch/arm/cpu/cache-armv7.S
+++ b/arch/arm/cpu/cache-armv7.S
@@ -50,7 +50,6 @@ ENTRY(__mmu_cache_off)
 		mov	pc, r12
 ENDPROC(__mmu_cache_off)
 
-__BARE_INIT
 ENTRY(__mmu_cache_flush)
 		mrc	p15, 0, r10, c0, c1, 5	@ read ID_MMFR1
 		tst	r10, #0xf << 16		@ hierarchical cache (ARMv7)
diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 0fcc950..f2f6173 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -75,12 +75,6 @@ void __naked __bare_init reset(void)
 #ifdef CONFIG_ARCH_HAS_LOWLEVEL_INIT
 	arch_init_lowlevel();
 #endif
-	__asm__ __volatile__ (
-		"bl __mmu_cache_flush;"
-		:
-		:
-		: "r0", "r1", "r2", "r3", "r6", "r10", "r12", "lr", "cc", "memory"
-	);
 
 	/* disable MMU stuff and caches */
 	r = get_cr();
-- 
1.7.10


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