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authorSricharan R <r.sricharan@ti.com>2013-07-29 20:26:22 +0530
committerSantosh Shilimkar <santosh.shilimkar@ti.com>2013-10-10 20:25:06 -0400
commitf52bb722547f43caeaecbcc62db9f3c3b80ead9b (patch)
tree99c0fbf6fb94053b5ed81ebfc84ee7010871f05d /arch/arm/kernel/head.S
parentc1a5f4f6733e39c3b780ff14ad6a68252475e7a9 (diff)
ARM: mm: Correct virt_to_phys patching for 64 bit physical addresses
The current phys_to_virt patching mechanism works only for 32 bit physical addresses and this patch extends the idea for 64bit physical addresses. The 64bit v2p patching mechanism patches the higher 8 bits of physical address with a constant using 'mov' instruction and lower 32bits are patched using 'add'. While this is correct, in those platforms where the lowmem addressable physical memory spawns across 4GB boundary, a carry bit can be produced as a result of addition of lower 32bits. This has to be taken in to account and added in to the upper. The patched __pv_offset and va are added in lower 32bits, where __pv_offset can be in two's complement form when PA_START < VA_START and that can result in a false carry bit. e.g 1) PA = 0x80000000; VA = 0xC0000000 __pv_offset = PA - VA = 0xC0000000 (2's complement) 2) PA = 0x2 80000000; VA = 0xC000000 __pv_offset = PA - VA = 0x1 C0000000 So adding __pv_offset + VA should never result in a true overflow for (1). So in order to differentiate between a true carry, a __pv_offset is extended to 64bit and the upper 32bits will have 0xffffffff if __pv_offset is 2's complement. So 'mvn #0' is inserted instead of 'mov' while patching for the same reason. Since mov, add, sub instruction are to patched with different constants inside the same stub, the rotation field of the opcode is using to differentiate between them. So the above examples for v2p translation becomes for VA=0xC0000000, 1) PA[63:32] = 0xffffffff PA[31:0] = VA + 0xC0000000 --> results in a carry PA[63:32] = PA[63:32] + carry PA[63:0] = 0x0 80000000 2) PA[63:32] = 0x1 PA[31:0] = VA + 0xC0000000 --> results in a carry PA[63:32] = PA[63:32] + carry PA[63:0] = 0x2 80000000 The above ideas were suggested by Nicolas Pitre <nico@linaro.org> as part of the review of first and second versions of the subject patch. There is no corresponding change on the phys_to_virt() side, because computations on the upper 32-bits would be discarded anyway. Cc: Russell King <linux@arm.linux.org.uk> Reviewed-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Sricharan R <r.sricharan@ti.com> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Diffstat (limited to 'arch/arm/kernel/head.S')
-rw-r--r--arch/arm/kernel/head.S63
1 files changed, 47 insertions, 16 deletions
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 2c7cc1e03473..54547947a4e9 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -536,6 +536,14 @@ ENTRY(fixup_smp)
ldmfd sp!, {r4 - r6, pc}
ENDPROC(fixup_smp)
+#ifdef __ARMEB_
+#define LOW_OFFSET 0x4
+#define HIGH_OFFSET 0x0
+#else
+#define LOW_OFFSET 0x0
+#define HIGH_OFFSET 0x4
+#endif
+
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
/* __fixup_pv_table - patch the stub instructions with the delta between
@@ -546,17 +554,20 @@ ENDPROC(fixup_smp)
__HEAD
__fixup_pv_table:
adr r0, 1f
- ldmia r0, {r3-r5, r7}
- sub r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
+ ldmia r0, {r3-r7}
+ mvn ip, #0
+ subs r3, r0, r3 @ PHYS_OFFSET - PAGE_OFFSET
add r4, r4, r3 @ adjust table start address
add r5, r5, r3 @ adjust table end address
- add r7, r7, r3 @ adjust __pv_phys_offset address
- str r8, [r7] @ save computed PHYS_OFFSET to __pv_phys_offset
+ add r6, r6, r3 @ adjust __pv_phys_offset address
+ add r7, r7, r3 @ adjust __pv_offset address
+ str r8, [r6, #LOW_OFFSET] @ save computed PHYS_OFFSET to __pv_phys_offset
+ strcc ip, [r7, #HIGH_OFFSET] @ save to __pv_offset high bits
mov r6, r3, lsr #24 @ constant for add/sub instructions
teq r3, r6, lsl #24 @ must be 16MiB aligned
THUMB( it ne @ cross section branch )
bne __error
- str r6, [r7, #4] @ save to __pv_offset
+ str r3, [r7, #LOW_OFFSET] @ save to __pv_offset low bits
b __fixup_a_pv_table
ENDPROC(__fixup_pv_table)
@@ -565,10 +576,19 @@ ENDPROC(__fixup_pv_table)
.long __pv_table_begin
.long __pv_table_end
2: .long __pv_phys_offset
+ .long __pv_offset
.text
__fixup_a_pv_table:
+ adr r0, 3f
+ ldr r6, [r0]
+ add r6, r6, r3
+ ldr r0, [r6, #HIGH_OFFSET] @ pv_offset high word
+ ldr r6, [r6, #LOW_OFFSET] @ pv_offset low word
+ mov r6, r6, lsr #24
+ cmn r0, #1
#ifdef CONFIG_THUMB2_KERNEL
+ moveq r0, #0x200000 @ set bit 21, mov to mvn instruction
lsls r6, #24
beq 2f
clz r7, r6
@@ -582,18 +602,28 @@ __fixup_a_pv_table:
b 2f
1: add r7, r3
ldrh ip, [r7, #2]
- and ip, 0x8f00
- orr ip, r6 @ mask in offset bits 31-24
+ tst ip, #0x4000
+ and ip, #0x8f00
+ orrne ip, r6 @ mask in offset bits 31-24
+ orreq ip, r0 @ mask in offset bits 7-0
strh ip, [r7, #2]
+ ldrheq ip, [r7]
+ biceq ip, #0x20
+ orreq ip, ip, r0, lsr #16
+ strheq ip, [r7]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
bcc 1b
bx lr
#else
+ moveq r0, #0x400000 @ set bit 22, mov to mvn instruction
b 2f
1: ldr ip, [r7, r3]
bic ip, ip, #0x000000ff
- orr ip, ip, r6 @ mask in offset bits 31-24
+ tst ip, #0xf00 @ check the rotation field
+ orrne ip, ip, r6 @ mask in offset bits 31-24
+ biceq ip, ip, #0x400000 @ clear bit 22
+ orreq ip, ip, r0 @ mask in offset bits 7-0
str ip, [r7, r3]
2: cmp r4, r5
ldrcc r7, [r4], #4 @ use branch for delay slot
@@ -602,28 +632,29 @@ __fixup_a_pv_table:
#endif
ENDPROC(__fixup_a_pv_table)
+3: .long __pv_offset
+
ENTRY(fixup_pv_table)
stmfd sp!, {r4 - r7, lr}
- ldr r2, 2f @ get address of __pv_phys_offset
mov r3, #0 @ no offset
mov r4, r0 @ r0 = table start
add r5, r0, r1 @ r1 = table size
- ldr r6, [r2, #4] @ get __pv_offset
bl __fixup_a_pv_table
ldmfd sp!, {r4 - r7, pc}
ENDPROC(fixup_pv_table)
- .align
-2: .long __pv_phys_offset
-
.data
.globl __pv_phys_offset
.type __pv_phys_offset, %object
__pv_phys_offset:
- .long 0
- .size __pv_phys_offset, . - __pv_phys_offset
+ .quad 0
+ .size __pv_phys_offset, . -__pv_phys_offset
+
+ .globl __pv_offset
+ .type __pv_offset, %object
__pv_offset:
- .long 0
+ .quad 0
+ .size __pv_offset, . -__pv_offset
#endif
#include "head-common.S"