/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 1994-2002 Russell King
* Copyright (c) 2003, 2020 ARM Limited
* All Rights Reserved
*/
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/page.h>
#ifdef __ARMEB__
#define LOW_OFFSET 0x4
#define HIGH_OFFSET 0x0
#else
#define LOW_OFFSET 0x0
#define HIGH_OFFSET 0x4
#endif
/*
* __fixup_pv_table - patch the stub instructions with the delta between
* PHYS_OFFSET and PAGE_OFFSET, which is assumed to be
* 2 MiB aligned.
*
* Called from head.S, which expects the following registers to be preserved:
* r1 = machine no, r2 = atags or dtb,
* r8 = phys_offset, r9 = cpuid, r10 = procinfo
*/
__HEAD
ENTRY(__fixup_pv_table)
mov r0, r8, lsr #PAGE_SHIFT @ convert to PFN
str_l r0, __pv_phys_pfn_offset, r3
adr_l r0, __pv_offset
subs r3, r8, #PAGE_OFFSET @ PHYS_OFFSET - PAGE_OFFSET
mvn ip, #0
strcc ip, [r0, #HIGH_OFFSET] @ save to __pv_offset high bits
str r3, [r0, #LOW_OFFSET] @ save to __pv_offset low bits
mov r0, r3, lsr #21 @ constant for add/sub instructions
teq r3, r0, lsl #21 @ must be 2 MiB aligned
bne 0f
adr_l r4, __pv_table_begin
adr_l r5, __pv_table_end
b __fixup_a_pv_table
0: mov r0, r0 @ deadloop on error
b 0b
ENDPROC(__fixup_pv_table)
.text
__fixup_a_pv_table:
adr_l r6, __pv_offset
ldr r0, [r6, #HIGH_OFFSET] @ pv_offset high word
ldr r6, [r6, #LOW_OFFSET] @ pv_offset low word
cmn r0, #1
#ifdef CONFIG_THUMB2_KERNEL
@
@ The Thumb-2 versions of the patchable sequences are
@
@ phys-to-virt: movw <reg>, #offset<31:21>
@ lsl <reg>, #21
@ sub <VA>, <PA>, <reg>
@
@ virt-to-phys (non-LPAE): movw <reg>, #offset<31:21>
@ lsl <reg>, #21
@ add <PA>, <VA>, <reg>
@
@ virt-to-phys (LPAE): movw <reg>, #offset<31:21>
@ lsl <reg>, #21
@ adds <PAlo>, <VA>, <reg>
@ mov <PAhi>, #offset<39:32>
@ adc <PAhi>, <PAhi>, #0
@
@ In the non-LPAE case, all patchable instructions are MOVW
@ instructions, where we need to patch in the offset into the
@ second halfword of the opcode (the 16-bit immediate is encoded
@ as imm4:i:imm3:imm8)
@
@ 15 11 10 9 4 3 0 15 14 12 11 8 7 0
@ +-----------+---+-------------+------++---+------+----+------+
@ MOVW | 1 1 1 1 0 | i | 1 0 0 1 0 0 | imm4 || 0 | imm3 | Rd | imm8 |
@ +-----------+---+-------------+------++---+------+----+------+
@
@ In the LPAE case, we also need to patch in the high word of the
@ offset into the immediate field of the MOV instruction, or patch it
@ to a MVN instruction if the offset is negative. In this case, we
@ need to inspect the first halfword of the opcode, to check whether
@ it is MOVW or MOV/MVN, and to perform the MOV to MVN patching if
@ needed. The encoding of the immediate is rather complex for values
@ of i:imm3 != 0b0000, but fortunately, we never need more than 8 lower
@ order bits, which can be patched into imm8 directly (and i:imm3
@ cleared)
@
@ 15 11 10 9 5 0 15 14 12 11 8 7 0
@ +-----------+---+---------------------++---+------+----+------+
@ MOV | 1 1 1 1 0 | i | 0 0 0 1 0 0 1 1 1 1 || 0 | imm3 | Rd | imm8 |
@ MVN | 1 1 1 1 0 | i | 0 0 0 1 1 0 1 1 1 1 || 0 | imm3 | Rd | imm8 |
@ +-----------+---+---------------------++---+------+----+------+
@
moveq r0, #0x200000 @ set bit 21, mov to mvn instruction
lsrs r3, r6, #29 @ isolate top 3 bits of displacement
ubfx r6, r6, #21, #8 @ put bits 28:21 into the MOVW imm8 field
bfi r6, r3, #12, #3 @ put bits 31:29 into the MOVW imm3 field
b .Lnext
.Lloop: add r7, r4
adds r4, #4 @ clears Z flag
#ifdef CONFIG_ARM_LPAE
ldrh ip, [r7]
ARM_BE8(rev16 ip, ip)
tst ip, #0x200 @ MOVW has bit 9 set, MVN has it clear
bne 0f @ skip to MOVW handling (Z flag is clear)
bic ip, #0x20 @ clear bit 5 (MVN -> MOV)
orr ip, ip, r0, lsr #16 @ MOV -> MVN if offset < 0
ARM_BE8(rev16 ip, ip)
strh ip, [r7]
@ Z flag is set
0:
#endif
ldrh ip, [r7, #2]
ARM_BE8(rev16 ip, ip)
and ip, #0xf00 @ clear everything except Rd field
orreq ip, r0 @ Z flag set -> MOV/MVN -> patch in high bits
orrne ip, r6 @ Z flag clear -> MOVW -> patch in low bits
ARM_BE8(rev16 ip, ip)
strh ip, [r7, #2]
#else
#ifdef CONFIG_CPU_ENDIAN_BE8
@ in BE8, we load data in BE, but instructions still in LE
#define PV_BIT24 0x00000001
#define PV_IMM8_MASK 0xff000000
#define PV_IMMR_MSB 0x00080000
#else
#define PV_BIT24 0x01000000
#define PV_IMM8_MASK 0x000000ff
#define PV_IMMR_MSB 0x00000800
#endif
@
@ The ARM versions of the patchable sequences are
@
@ phys-to-virt: sub <VA>, <PA>, #offset<31:24>, lsl #24
@ sub <VA>, <PA>, #offset<23:16>, lsl #16
@
@ virt-to-phys (non-LPAE): add <PA>, <VA>, #offset<31:24>, lsl #24
@ add <PA>, <VA>, #offset<23:16>, lsl #16
@
@ virt-to-phys (LPAE): movw <reg>, #offset<31:20>
@ adds <PAlo>, <VA>, <reg>, lsl #20
@ mov <PAhi>, #offset<39:32>
@ adc <PAhi>, <PAhi>, #0
@
@ In the non-LPAE case, all patchable instructions are ADD or SUB
@ instructions, where we need to patch in the offset into the
@ immediate field of the opcode, which is emitted with the correct
@ rotation value. (The effective value of the immediate is imm12<7:0>
@ rotated right by [2 * imm12<11:8>] bits)
@
@ 31 28 27 23 22 20 19 16 15 12 11 0
@ +------+-----------------+------+------+-------+
@ ADD | cond | 0 0 1 0 1 0 0 0 | Rn | Rd | imm12 |
@ SUB | cond | 0 0 1 0 0 1 0 0 | Rn | Rd | imm12 |
@ MOV | cond | 0 0 1 1 1 0 1 0 | Rn | Rd | imm12 |
@ MVN | cond | 0 0 1 1 1 1 1 0 | Rn | Rd | imm12 |
@ +------+-----------------+------+------+-------+
@
@ In the LPAE case, we use a MOVW instruction to carry the low offset
@ word, and patch in the high word of the offset into the immediate
@ field of the subsequent MOV instruction, or patch it to a MVN
@ instruction if the offset is negative. We can distinguish MOVW
@ instructions based on bits 23:22 of the opcode, and ADD/SUB can be
@ distinguished from MOV/MVN (all using the encodings above) using
@ bit 24.
@
@ 31 28 27 23 22 20 19 16 15 12 11 0
@ +------+-----------------+------+------+-------+
@ MOVW | cond | 0 0 1 1 0 0 0 0 | imm4 | Rd | imm12 |
@ +------+-----------------+------+------+-------+
@
moveq r0, #0x400000 @ set bit 22, mov to mvn instruction
mov r3, r6, lsr #16 @ put offset bits 31-16 into r3
mov r6, r6, lsr #24 @ put offset bits 31-24 into r6
and r3, r3, #0xf0 @ only keep offset bits 23-20 in r3
b .Lnext
.Lloop: ldr ip, [r7, r4]
#ifdef CONFIG_ARM_LPAE
tst ip, #PV_BIT24 @ ADD/SUB have bit 24 clear
beq 1f
ARM_BE8(rev ip, ip)
tst ip, #0xc00000 @ MOVW has bits 23:22 clear
bic ip, ip, #0x400000 @ clear bit 22
bfc ip, #0, #12 @ clear imm12 field of MOV[W] instruction
orreq ip, ip, r6, lsl #4 @ MOVW -> mask in offset bits 31-24
orreq ip, ip, r3, lsr #4 @ MOVW -> mask in offset bits 23-20
orrne ip, ip, r0 @ MOV -> mask in offset bits 7-0 (or bit 22)
ARM_BE8(rev ip, ip)
b 2f
1:
#endif
tst ip, #PV_IMMR_MSB @ rotation value >= 16 ?
bic ip, ip, #PV_IMM8_MASK
orreq ip, ip, r6 ARM_BE8(, lsl #24) @ mask in offset bits 31-24
orrne ip, ip, r3 ARM_BE8(, lsl #24) @ mask in offset bits 23-20
2:
str ip, [r7, r4]
add r4, r4, #4
#endif
.Lnext:
cmp r4, r5
ldrcc r7, [r4] @ use branch for delay slot
bcc .Lloop
ret lr
ENDPROC(__fixup_a_pv_table)
ENTRY(fixup_pv_table)
stmfd sp!, {r4 - r7, lr}
mov r4, r0 @ r0 = table start
add r5, r0, r1 @ r1 = table size
bl __fixup_a_pv_table
ldmfd sp!, {r4 - r7, pc}
ENDPROC(fixup_pv_table)
.data
.align 2
.globl __pv_phys_pfn_offset
.type __pv_phys_pfn_offset, %object
__pv_phys_pfn_offset:
.word 0
.size __pv_phys_pfn_offset, . -__pv_phys_pfn_offset
.globl __pv_offset
.type __pv_offset, %object
__pv_offset:
.quad 0
.size __pv_offset, . -__pv_offset