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ARM: 6747/1: P2V: Thumb2 support 

Adding Thumb2 support to the runtime patching of the virt_to_phys and
phys_to_virt opcodes.

Tested both the 8-bit and the 16-bit fixups, using different placements
in memory to exercize all code paths.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Nicolas Pitre 2011-02-21 06:53:35 +01:00 committed by Russell King
parent 80f0aad77f
commit b511d75d61
2 changed files with 50 additions and 3 deletions
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4
arch/arm/Kconfig
View File

@ -194,13 +194,13 @@ config VECTORS_BASE
config ARM_PATCH_PHYS_VIRT
bool "Patch physical to virtual translations at runtime (EXPERIMENTAL)"
depends on EXPERIMENTAL
depends on !XIP_KERNEL && !THUMB2_KERNEL && MMU
depends on !XIP_KERNEL && MMU
depends on !ARCH_REALVIEW || !SPARSEMEM
help
Patch phys-to-virt translation functions at runtime according to
the position of the kernel in system memory.
This can only be used with non-XIP, non-Thumb2, MMU kernels where
This can only be used with non-XIP with MMU kernels where
the base of physical memory is at a 16MB boundary.
config ARM_PATCH_PHYS_VIRT_16BIT

49
arch/arm/kernel/head.S
View File

@ -461,7 +461,8 @@ __fixup_pv_table:
sub r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
add r4, r4, r3 @ adjust table start address
add r5, r5, r3 @ adjust table end address
str r8, [r7, r3]! @ save computed PHYS_OFFSET to __pv_phys_offset
add r7, r7, r3 @ adjust __pv_phys_offset address
str r8, [r7] @ save computed PHYS_OFFSET to __pv_phys_offset
#ifndef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT
mov r6, r3, lsr #24 @ constant for add/sub instructions
teq r3, r6, lsl #24 @ must be 16MiB aligned
@ -469,6 +470,7 @@ __fixup_pv_table:
mov r6, r3, lsr #16 @ constant for add/sub instructions
teq r3, r6, lsl #16 @ must be 64kiB aligned
#endif
THUMB( it ne @ cross section branch )
bne __error
str r6, [r7, #4] @ save to __pv_offset
b __fixup_a_pv_table
@ -482,6 +484,50 @@ ENDPROC(__fixup_pv_table)
.text
__fixup_a_pv_table:
#ifdef CONFIG_THUMB2_KERNEL
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT
lsls r0, r6, #24
lsr r6, #8
beq 1f
clz r7, r0
lsr r0, #24
lsl r0, r7
bic r0, 0x0080
lsrs r7, #1
orrcs r0, #0x0080
orr r0, r0, r7, lsl #12
#endif
1: lsls r6, #24
beq 4f
clz r7, r6
lsr r6, #24
lsl r6, r7
bic r6, #0x0080
lsrs r7, #1
orrcs r6, #0x0080
orr r6, r6, r7, lsl #12
orr r6, #0x4000
b 4f
2: @ at this point the C flag is always clear
add r7, r3
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT
ldrh ip, [r7]
tst ip, 0x0400 @ the i bit tells us LS or MS byte
beq 3f
cmp r0, #0 @ set C flag, and ...
biceq ip, 0x0400 @ immediate zero value has a special encoding
streqh ip, [r7] @ that requires the i bit cleared
#endif
3: ldrh ip, [r7, #2]
and ip, 0x8f00
orrcc ip, r6 @ mask in offset bits 31-24
orrcs ip, r0 @ mask in offset bits 23-16
strh ip, [r7, #2]
4: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 2b
bx lr
#else
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT_16BIT
and r0, r6, #255 @ offset bits 23-16
mov r6, r6, lsr #8 @ offset bits 31-24
@ -499,6 +545,7 @@ __fixup_a_pv_table:
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 2b
mov pc, lr
#endif
ENDPROC(__fixup_a_pv_table)
ENTRY(fixup_pv_table)