[PATCH 03/14] ARM: fixup_pv_table bug when CPU_ENDIAN_BE8

Ben Dooks
2013-07-24T10:27:51Z

The fixup_pv_table assumes that the instructions are in the same
endian configuration as the data, but when the CPU is running in
BE8 the instructions stay in little-endian format.

Make sure if CONFIG_CPU_ENDIAN_BE8 is set that we do all the
alterations to the instructions taking in to account the LDR/STR
will be swapping the data endian-ness.

Since the code is only modifying a byte, we avoid dual-swapping
the data, and just change the bits we clear and ORR in (in the
case where the code is not thumb2).

For thumb2, we add the necessary rev16 instructions to ensure that
the instructions are processed in the correct format, as it was
easier than re-writing the code to contain a mask and shift.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
arch/arm/kernel/head.S | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 8bac553..e40c0b3b 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -584,8 +584,10 @@ __fixup_a_pv_table:
b 2f
1: add r7, r3
ldrh ip, [r7, #2]
+ARM_BE8(rev16 ip, ip)
and ip, 0x8f00
orr ip, r6 @ mask in offset bits 31-24
+ARM_BE8(rev16 ip, ip)
strh ip, [r7, #2]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
@@ -594,8 +596,14 @@ __fixup_a_pv_table:
#else
b 2f
1: ldr ip, [r7, r3]
+#ifdef CONFIG_CPU_ENDIAN_BE8
+ @ in BE8, we load data in BE, but instructions still in LE
+ bic ip, ip, #0xff000000
+ orr ip, ip, r6, lsl#24
+#else
bic ip, ip, #0x000000ff
orr ip, ip, r6 @ mask in offset bits 31-24
+#endif
str ip, [r7, r3]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
--
1.7.10.4