At least the iMX6 boot rom seems to jump into barebox with a non
invalidated d-cache which causes data corruption when
v7_mmu_cache_flush() executed by arm_early_mmu_cache_flush() overrides
stack or other valid data.
That's why the cache must be invalided for this processors explicitly
(e.g. in barebox_arm_reset_vector()). Operation differs from flush only
in one instruction so that patch modifies the existing
v7_mmu_cache_flush() function slightly by adding an optional argument.
Signed-off-by: Enrico Scholz <enrico.scholz@xxxxxxxxxxxxxxxxx>
---
arch/arm/cpu/cache-armv7.S | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/arch/arm/cpu/cache-armv7.S b/arch/arm/cpu/cache-armv7.S
index 5595cf6..84c833e 100644
--- a/arch/arm/cpu/cache-armv7.S
+++ b/arch/arm/cpu/cache-armv7.S
@@ -57,7 +57,17 @@ ENTRY(v7_mmu_cache_off)
ENDPROC(v7_mmu_cache_off)
.section .text.v7_mmu_cache_flush
+ENTRY(v7_mmu_cache_invalidate)
+ mov r0, #1
+ b _v7_mmu_cache_flush
+ENDPROC(v7_mmu_cache_invalidate)
+
ENTRY(v7_mmu_cache_flush)
+ mov r0, #0
+ b _v7_mmu_cache_flush
+ENDPROC(v7_mmu_cache_flush)
+
+ENTRY(_v7_mmu_cache_flush)
mrc p15, 0, r12, c0, c1, 5 @ read ID_MMFR1
tst r12, #0xf << 16 @ hierarchical cache (ARMv7)
mov r12, #0
@@ -65,7 +75,8 @@ ENTRY(v7_mmu_cache_flush)
mcr p15, 0, r12, c7, c14, 0 @ clean+invalidate D
b iflush
hierarchical:
- stmfd sp!, {r4-r7, r9-r11}
+ stmfd sp!, {r4-r11}
+ mov r8, r0
mcr p15, 0, r12, c7, c10, 5 @ DMB
mrc p15, 1, r0, c0, c0, 1 @ read clidr
ands r3, r0, #0x7000000 @ extract loc from clidr
@@ -97,7 +108,10 @@ THUMB( lsl r6, r9, r5 )
THUMB( orr r11, r12, r6 ) @ factor way and cache number into r11
THUMB( lsl r6, r7, r2 )
THUMB( orr r11, r11, r6 ) @ factor index number into r11
- mcr p15, 0, r11, c7, c14, 2 @ clean & invalidate by set/way
+ cmp r8, #0
+THUMB( ite eq)
+ mcreq p15, 0, r11, c7, c14, 2 @ clean & invalidate by set/way
+ mcrne p15, 0, r11, c7, c6, 2 @ invalidate by set/way
subs r9, r9, #1 @ decrement the way
bge loop3
subs r7, r7, #1 @ decrement the index
@@ -107,7 +121,7 @@ skip:
cmp r3, r12
bgt loop1
finished:
- ldmfd sp!, {r4-r7, r9-r11}
+ ldmfd sp!, {r4-r11}
mov r12, #0 @ switch back to cache level 0
mcr p15, 2, r12, c0, c0, 0 @ select current cache level in cssr
iflush:
@@ -116,7 +130,7 @@ iflush:
mcr p15, 0, r12, c7, c10, 4 @ DSB
mcr p15, 0, r12, c7, c5, 4 @ ISB
mov pc, lr
-ENDPROC(v7_mmu_cache_flush)
+ENDPROC(_v7_mmu_cache_flush)
/*
* cache_line_size - get the cache line size from the CSIDR register
--
1.8.1.4
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