[PATCH 03/19] ARM: fixup_pv_table bug when CPU_ENDIAN_BE8

Ben Dooks ben.dooks at codethink.co.uk
Tue Aug 27 17:38:13 EDT 2013

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 at 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 2c7cc1e..9e5906c 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -582,8 +582,10 @@ __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
@@ -592,8 +594,14 @@ __fixup_a_pv_table:
 	b	2f
 1:	ldr	ip, [r7, r3]
+	@ in BE8, we load data in BE, but instructions still in LE
+	bic	ip, ip, #0xff000000
+	orr	ip, ip, r6, lsl#24
 	bic	ip, ip, #0x000000ff
 	orr	ip, ip, r6	@ mask in offset bits 31-24
 	str	ip, [r7, r3]
 2:	cmp	r4, r5
 	ldrcc	r7, [r4], #4	@ use branch for delay slot

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