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Diffstat (limited to 'arch/arm/kernel/phys2virt.S')
| -rw-r--r-- | arch/arm/kernel/phys2virt.S | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/arch/arm/kernel/phys2virt.S b/arch/arm/kernel/phys2virt.S new file mode 100644 index 000000000..fb53db78f --- /dev/null +++ b/arch/arm/kernel/phys2virt.S @@ -0,0 +1,238 @@ +/* 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 |