diff options
Diffstat (limited to 'arch/arc/kernel/disasm.c')
| -rw-r--r-- | arch/arc/kernel/disasm.c | 594 |
1 files changed, 594 insertions, 0 deletions
diff --git a/arch/arc/kernel/disasm.c b/arch/arc/kernel/disasm.c new file mode 100644 index 0000000000..ccc7e8c39e --- /dev/null +++ b/arch/arc/kernel/disasm.c @@ -0,0 +1,594 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * several functions that help interpret ARC instructions + * used for unaligned accesses, kprobes and kgdb + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include <linux/types.h> +#include <linux/kprobes.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <asm/disasm.h> + +#if defined(CONFIG_KGDB) || defined(CONFIG_ARC_EMUL_UNALIGNED) || \ + defined(CONFIG_KPROBES) + +/* disasm_instr: Analyses instruction at addr, stores + * findings in *state + */ +void __kprobes disasm_instr(unsigned long addr, struct disasm_state *state, + int userspace, struct pt_regs *regs, struct callee_regs *cregs) +{ + int fieldA = 0; + int fieldC = 0, fieldCisReg = 0; + uint16_t word1 = 0, word0 = 0; + int subopcode, is_linked, op_format; + uint16_t *ins_ptr; + uint16_t ins_buf[4]; + int bytes_not_copied = 0; + + memset(state, 0, sizeof(struct disasm_state)); + + /* This fetches the upper part of the 32 bit instruction + * in both the cases of Little Endian or Big Endian configurations. */ + if (userspace) { + bytes_not_copied = copy_from_user(ins_buf, + (const void __user *) addr, 8); + if (bytes_not_copied > 6) + goto fault; + ins_ptr = ins_buf; + } else { + ins_ptr = (uint16_t *) addr; + } + + word1 = *((uint16_t *)addr); + + state->major_opcode = (word1 >> 11) & 0x1F; + + /* Check if the instruction is 32 bit or 16 bit instruction */ + if (state->major_opcode < 0x0B) { + if (bytes_not_copied > 4) + goto fault; + state->instr_len = 4; + word0 = *((uint16_t *)(addr+2)); + state->words[0] = (word1 << 16) | word0; + } else { + state->instr_len = 2; + state->words[0] = word1; + } + + /* Read the second word in case of limm */ + word1 = *((uint16_t *)(addr + state->instr_len)); + word0 = *((uint16_t *)(addr + state->instr_len + 2)); + state->words[1] = (word1 << 16) | word0; + + switch (state->major_opcode) { + case op_Bcc: + state->is_branch = 1; + + /* unconditional branch s25, conditional branch s21 */ + fieldA = (IS_BIT(state->words[0], 16)) ? + FIELD_s25(state->words[0]) : + FIELD_s21(state->words[0]); + + state->delay_slot = IS_BIT(state->words[0], 5); + state->target = fieldA + (addr & ~0x3); + state->flow = direct_jump; + break; + + case op_BLcc: + if (IS_BIT(state->words[0], 16)) { + /* Branch and Link*/ + /* unconditional branch s25, conditional branch s21 */ + fieldA = (IS_BIT(state->words[0], 17)) ? + (FIELD_s25(state->words[0]) & ~0x3) : + FIELD_s21(state->words[0]); + + state->flow = direct_call; + } else { + /*Branch On Compare */ + fieldA = FIELD_s9(state->words[0]) & ~0x3; + state->flow = direct_jump; + } + + state->delay_slot = IS_BIT(state->words[0], 5); + state->target = fieldA + (addr & ~0x3); + state->is_branch = 1; + break; + + case op_LD: /* LD<zz> a,[b,s9] */ + state->write = 0; + state->di = BITS(state->words[0], 11, 11); + if (state->di) + break; + state->x = BITS(state->words[0], 6, 6); + state->zz = BITS(state->words[0], 7, 8); + state->aa = BITS(state->words[0], 9, 10); + state->wb_reg = FIELD_B(state->words[0]); + if (state->wb_reg == REG_LIMM) { + state->instr_len += 4; + state->aa = 0; + state->src1 = state->words[1]; + } else { + state->src1 = get_reg(state->wb_reg, regs, cregs); + } + state->src2 = FIELD_s9(state->words[0]); + state->dest = FIELD_A(state->words[0]); + state->pref = (state->dest == REG_LIMM); + break; + + case op_ST: + state->write = 1; + state->di = BITS(state->words[0], 5, 5); + if (state->di) + break; + state->aa = BITS(state->words[0], 3, 4); + state->zz = BITS(state->words[0], 1, 2); + state->src1 = FIELD_C(state->words[0]); + if (state->src1 == REG_LIMM) { + state->instr_len += 4; + state->src1 = state->words[1]; + } else { + state->src1 = get_reg(state->src1, regs, cregs); + } + state->wb_reg = FIELD_B(state->words[0]); + if (state->wb_reg == REG_LIMM) { + state->aa = 0; + state->instr_len += 4; + state->src2 = state->words[1]; + } else { + state->src2 = get_reg(state->wb_reg, regs, cregs); + } + state->src3 = FIELD_s9(state->words[0]); + break; + + case op_MAJOR_4: + subopcode = MINOR_OPCODE(state->words[0]); + switch (subopcode) { + case 32: /* Jcc */ + case 33: /* Jcc.D */ + case 34: /* JLcc */ + case 35: /* JLcc.D */ + is_linked = 0; + + if (subopcode == 33 || subopcode == 35) + state->delay_slot = 1; + + if (subopcode == 34 || subopcode == 35) + is_linked = 1; + + fieldCisReg = 0; + op_format = BITS(state->words[0], 22, 23); + if (op_format == 0 || ((op_format == 3) && + (!IS_BIT(state->words[0], 5)))) { + fieldC = FIELD_C(state->words[0]); + + if (fieldC == REG_LIMM) { + fieldC = state->words[1]; + state->instr_len += 4; + } else { + fieldCisReg = 1; + } + } else if (op_format == 1 || ((op_format == 3) + && (IS_BIT(state->words[0], 5)))) { + fieldC = FIELD_C(state->words[0]); + } else { + /* op_format == 2 */ + fieldC = FIELD_s12(state->words[0]); + } + + if (!fieldCisReg) { + state->target = fieldC; + state->flow = is_linked ? + direct_call : direct_jump; + } else { + state->target = get_reg(fieldC, regs, cregs); + state->flow = is_linked ? + indirect_call : indirect_jump; + } + state->is_branch = 1; + break; + + case 40: /* LPcc */ + if (BITS(state->words[0], 22, 23) == 3) { + /* Conditional LPcc u7 */ + fieldC = FIELD_C(state->words[0]); + + fieldC = fieldC << 1; + fieldC += (addr & ~0x03); + state->is_branch = 1; + state->flow = direct_jump; + state->target = fieldC; + } + /* For Unconditional lp, next pc is the fall through + * which is updated */ + break; + + case 48 ... 55: /* LD a,[b,c] */ + state->di = BITS(state->words[0], 15, 15); + if (state->di) + break; + state->x = BITS(state->words[0], 16, 16); + state->zz = BITS(state->words[0], 17, 18); + state->aa = BITS(state->words[0], 22, 23); + state->wb_reg = FIELD_B(state->words[0]); + if (state->wb_reg == REG_LIMM) { + state->instr_len += 4; + state->src1 = state->words[1]; + } else { + state->src1 = get_reg(state->wb_reg, regs, + cregs); + } + state->src2 = FIELD_C(state->words[0]); + if (state->src2 == REG_LIMM) { + state->instr_len += 4; + state->src2 = state->words[1]; + } else { + state->src2 = get_reg(state->src2, regs, + cregs); + } + state->dest = FIELD_A(state->words[0]); + if (state->dest == REG_LIMM) + state->pref = 1; + break; + + case 10: /* MOV */ + /* still need to check for limm to extract instr len */ + /* MOV is special case because it only takes 2 args */ + switch (BITS(state->words[0], 22, 23)) { + case 0: /* OP a,b,c */ + if (FIELD_C(state->words[0]) == REG_LIMM) + state->instr_len += 4; + break; + case 1: /* OP a,b,u6 */ + break; + case 2: /* OP b,b,s12 */ + break; + case 3: /* OP.cc b,b,c/u6 */ + if ((!IS_BIT(state->words[0], 5)) && + (FIELD_C(state->words[0]) == REG_LIMM)) + state->instr_len += 4; + break; + } + break; + + + default: + /* Not a Load, Jump or Loop instruction */ + /* still need to check for limm to extract instr len */ + switch (BITS(state->words[0], 22, 23)) { + case 0: /* OP a,b,c */ + if ((FIELD_B(state->words[0]) == REG_LIMM) || + (FIELD_C(state->words[0]) == REG_LIMM)) + state->instr_len += 4; + break; + case 1: /* OP a,b,u6 */ + break; + case 2: /* OP b,b,s12 */ + break; + case 3: /* OP.cc b,b,c/u6 */ + if ((!IS_BIT(state->words[0], 5)) && + ((FIELD_B(state->words[0]) == REG_LIMM) || + (FIELD_C(state->words[0]) == REG_LIMM))) + state->instr_len += 4; + break; + } + break; + } + break; + + /* 16 Bit Instructions */ + case op_LD_ADD: /* LD_S|LDB_S|LDW_S a,[b,c] */ + state->zz = BITS(state->words[0], 3, 4); + state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs); + state->src2 = get_reg(FIELD_S_C(state->words[0]), regs, cregs); + state->dest = FIELD_S_A(state->words[0]); + break; + + case op_ADD_MOV_CMP: + /* check for limm, ignore mov_s h,b (== mov_s 0,b) */ + if ((BITS(state->words[0], 3, 4) < 3) && + (FIELD_S_H(state->words[0]) == REG_LIMM)) + state->instr_len += 4; + break; + + case op_S: + subopcode = BITS(state->words[0], 5, 7); + switch (subopcode) { + case 0: /* j_s */ + case 1: /* j_s.d */ + case 2: /* jl_s */ + case 3: /* jl_s.d */ + state->target = get_reg(FIELD_S_B(state->words[0]), + regs, cregs); + state->delay_slot = subopcode & 1; + state->flow = (subopcode >= 2) ? + direct_call : indirect_jump; + break; + case 7: + switch (BITS(state->words[0], 8, 10)) { + case 4: /* jeq_s [blink] */ + case 5: /* jne_s [blink] */ + case 6: /* j_s [blink] */ + case 7: /* j_s.d [blink] */ + state->delay_slot = (subopcode == 7); + state->flow = indirect_jump; + state->target = get_reg(31, regs, cregs); + default: + break; + } + default: + break; + } + break; + + case op_LD_S: /* LD_S c, [b, u7] */ + state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs); + state->src2 = FIELD_S_u7(state->words[0]); + state->dest = FIELD_S_C(state->words[0]); + break; + + case op_LDB_S: + case op_STB_S: + /* no further handling required as byte accesses should not + * cause an unaligned access exception */ + state->zz = 1; + break; + + case op_LDWX_S: /* LDWX_S c, [b, u6] */ + state->x = 1; + fallthrough; + + case op_LDW_S: /* LDW_S c, [b, u6] */ + state->zz = 2; + state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs); + state->src2 = FIELD_S_u6(state->words[0]); + state->dest = FIELD_S_C(state->words[0]); + break; + + case op_ST_S: /* ST_S c, [b, u7] */ + state->write = 1; + state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs); + state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs); + state->src3 = FIELD_S_u7(state->words[0]); + break; + + case op_STW_S: /* STW_S c,[b,u6] */ + state->write = 1; + state->zz = 2; + state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs); + state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs); + state->src3 = FIELD_S_u6(state->words[0]); + break; + + case op_SP: /* LD_S|LDB_S b,[sp,u7], ST_S|STB_S b,[sp,u7] */ + /* note: we are ignoring possibility of: + * ADD_S, SUB_S, PUSH_S, POP_S as these should not + * cause unaligned exception anyway */ + state->write = BITS(state->words[0], 6, 6); + state->zz = BITS(state->words[0], 5, 5); + if (state->zz) + break; /* byte accesses should not come here */ + if (!state->write) { + state->src1 = get_reg(28, regs, cregs); + state->src2 = FIELD_S_u7(state->words[0]); + state->dest = FIELD_S_B(state->words[0]); + } else { + state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, + cregs); + state->src2 = get_reg(28, regs, cregs); + state->src3 = FIELD_S_u7(state->words[0]); + } + break; + + case op_GP: /* LD_S|LDB_S|LDW_S r0,[gp,s11/s9/s10] */ + /* note: ADD_S r0, gp, s11 is ignored */ + state->zz = BITS(state->words[0], 9, 10); + state->src1 = get_reg(26, regs, cregs); + state->src2 = state->zz ? FIELD_S_s10(state->words[0]) : + FIELD_S_s11(state->words[0]); + state->dest = 0; + break; + + case op_Pcl: /* LD_S b,[pcl,u10] */ + state->src1 = regs->ret & ~3; + state->src2 = FIELD_S_u10(state->words[0]); + state->dest = FIELD_S_B(state->words[0]); + break; + + case op_BR_S: + state->target = FIELD_S_s8(state->words[0]) + (addr & ~0x03); + state->flow = direct_jump; + state->is_branch = 1; + break; + + case op_B_S: + fieldA = (BITS(state->words[0], 9, 10) == 3) ? + FIELD_S_s7(state->words[0]) : + FIELD_S_s10(state->words[0]); + state->target = fieldA + (addr & ~0x03); + state->flow = direct_jump; + state->is_branch = 1; + break; + + case op_BL_S: + state->target = FIELD_S_s13(state->words[0]) + (addr & ~0x03); + state->flow = direct_call; + state->is_branch = 1; + break; + + default: + break; + } + + if (bytes_not_copied <= (8 - state->instr_len)) + return; + +fault: state->fault = 1; +} + +long __kprobes get_reg(int reg, struct pt_regs *regs, + struct callee_regs *cregs) +{ + long *p; + +#if defined(CONFIG_ISA_ARCOMPACT) + if (reg <= 12) { + p = ®s->r0; + return p[-reg]; + } +#else /* CONFIG_ISA_ARCV2 */ + if (reg <= 11) { + p = ®s->r0; + return p[reg]; + } + + if (reg == 12) + return regs->r12; + if (reg == 30) + return regs->r30; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + if (reg == 58) + return regs->r58; + if (reg == 59) + return regs->r59; +#endif +#endif + if (cregs && (reg <= 25)) { + p = &cregs->r13; + return p[13 - reg]; + } + + if (reg == 26) + return regs->r26; + if (reg == 27) + return regs->fp; + if (reg == 28) + return regs->sp; + if (reg == 31) + return regs->blink; + + return 0; +} + +void __kprobes set_reg(int reg, long val, struct pt_regs *regs, + struct callee_regs *cregs) +{ + long *p; + +#if defined(CONFIG_ISA_ARCOMPACT) + switch (reg) { + case 0 ... 12: + p = ®s->r0; + p[-reg] = val; + break; + case 13 ... 25: + if (cregs) { + p = &cregs->r13; + p[13 - reg] = val; + } + break; + case 26: + regs->r26 = val; + break; + case 27: + regs->fp = val; + break; + case 28: + regs->sp = val; + break; + case 31: + regs->blink = val; + break; + default: + break; + } +#else /* CONFIG_ISA_ARCV2 */ + switch (reg) { + case 0 ... 11: + p = ®s->r0; + p[reg] = val; + break; + case 12: + regs->r12 = val; + break; + case 13 ... 25: + if (cregs) { + p = &cregs->r13; + p[13 - reg] = val; + } + break; + case 26: + regs->r26 = val; + break; + case 27: + regs->fp = val; + break; + case 28: + regs->sp = val; + break; + case 30: + regs->r30 = val; + break; + case 31: + regs->blink = val; + break; +#ifdef CONFIG_ARC_HAS_ACCL_REGS + case 58: + regs->r58 = val; + break; + case 59: + regs->r59 = val; + break; +#endif + default: + break; + } +#endif +} + +/* + * Disassembles the insn at @pc and sets @next_pc to next PC (which could be + * @pc +2/4/6 (ARCompact ISA allows free intermixing of 16/32 bit insns). + * + * If @pc is a branch + * -@tgt_if_br is set to branch target. + * -If branch has delay slot, @next_pc updated with actual next PC. + */ +int __kprobes disasm_next_pc(unsigned long pc, struct pt_regs *regs, + struct callee_regs *cregs, + unsigned long *next_pc, unsigned long *tgt_if_br) +{ + struct disasm_state instr; + + disasm_instr(pc, &instr, 0, regs, cregs); + + *next_pc = pc + instr.instr_len; + + /* Instruction with possible two targets branch, jump and loop */ + if (instr.is_branch) + *tgt_if_br = instr.target; + + /* For the instructions with delay slots, the fall through is the + * instruction following the instruction in delay slot. + */ + if (instr.delay_slot) { + struct disasm_state instr_d; + + disasm_instr(*next_pc, &instr_d, 0, regs, cregs); + + *next_pc += instr_d.instr_len; + } + + /* Zero Overhead Loop - end of the loop */ + if (!(regs->status32 & STATUS32_L) && (*next_pc == regs->lp_end) + && (regs->lp_count > 1)) { + *next_pc = regs->lp_start; + } + + return instr.is_branch; +} + +#endif /* CONFIG_KGDB || CONFIG_ARC_EMUL_UNALIGNED || CONFIG_KPROBES */ |