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378 lines
9.8 KiB
378 lines
9.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* SuperH KGDB support |
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* |
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* Copyright (C) 2008 - 2012 Paul Mundt |
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* |
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* Single stepping taken from the old stub by Henry Bell and Jeremy Siegel. |
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*/ |
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#include <linux/kgdb.h> |
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#include <linux/kdebug.h> |
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#include <linux/irq.h> |
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#include <linux/io.h> |
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#include <linux/sched.h> |
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#include <linux/sched/task_stack.h> |
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#include <asm/cacheflush.h> |
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#include <asm/traps.h> |
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/* Macros for single step instruction identification */ |
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#define OPCODE_BT(op) (((op) & 0xff00) == 0x8900) |
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#define OPCODE_BF(op) (((op) & 0xff00) == 0x8b00) |
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#define OPCODE_BTF_DISP(op) (((op) & 0x80) ? (((op) | 0xffffff80) << 1) : \ |
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(((op) & 0x7f ) << 1)) |
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#define OPCODE_BFS(op) (((op) & 0xff00) == 0x8f00) |
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#define OPCODE_BTS(op) (((op) & 0xff00) == 0x8d00) |
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#define OPCODE_BRA(op) (((op) & 0xf000) == 0xa000) |
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#define OPCODE_BRA_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \ |
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(((op) & 0x7ff) << 1)) |
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#define OPCODE_BRAF(op) (((op) & 0xf0ff) == 0x0023) |
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#define OPCODE_BRAF_REG(op) (((op) & 0x0f00) >> 8) |
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#define OPCODE_BSR(op) (((op) & 0xf000) == 0xb000) |
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#define OPCODE_BSR_DISP(op) (((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \ |
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(((op) & 0x7ff) << 1)) |
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#define OPCODE_BSRF(op) (((op) & 0xf0ff) == 0x0003) |
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#define OPCODE_BSRF_REG(op) (((op) >> 8) & 0xf) |
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#define OPCODE_JMP(op) (((op) & 0xf0ff) == 0x402b) |
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#define OPCODE_JMP_REG(op) (((op) >> 8) & 0xf) |
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#define OPCODE_JSR(op) (((op) & 0xf0ff) == 0x400b) |
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#define OPCODE_JSR_REG(op) (((op) >> 8) & 0xf) |
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#define OPCODE_RTS(op) ((op) == 0xb) |
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#define OPCODE_RTE(op) ((op) == 0x2b) |
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#define SR_T_BIT_MASK 0x1 |
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#define STEP_OPCODE 0xc33d |
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/* Calculate the new address for after a step */ |
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static short *get_step_address(struct pt_regs *linux_regs) |
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{ |
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insn_size_t op = __raw_readw(linux_regs->pc); |
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long addr; |
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/* BT */ |
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if (OPCODE_BT(op)) { |
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if (linux_regs->sr & SR_T_BIT_MASK) |
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addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); |
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else |
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addr = linux_regs->pc + 2; |
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} |
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/* BTS */ |
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else if (OPCODE_BTS(op)) { |
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if (linux_regs->sr & SR_T_BIT_MASK) |
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addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); |
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else |
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addr = linux_regs->pc + 4; /* Not in delay slot */ |
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} |
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/* BF */ |
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else if (OPCODE_BF(op)) { |
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if (!(linux_regs->sr & SR_T_BIT_MASK)) |
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addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); |
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else |
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addr = linux_regs->pc + 2; |
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} |
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/* BFS */ |
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else if (OPCODE_BFS(op)) { |
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if (!(linux_regs->sr & SR_T_BIT_MASK)) |
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addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op); |
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else |
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addr = linux_regs->pc + 4; /* Not in delay slot */ |
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} |
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/* BRA */ |
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else if (OPCODE_BRA(op)) |
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addr = linux_regs->pc + 4 + OPCODE_BRA_DISP(op); |
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/* BRAF */ |
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else if (OPCODE_BRAF(op)) |
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addr = linux_regs->pc + 4 |
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+ linux_regs->regs[OPCODE_BRAF_REG(op)]; |
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/* BSR */ |
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else if (OPCODE_BSR(op)) |
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addr = linux_regs->pc + 4 + OPCODE_BSR_DISP(op); |
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/* BSRF */ |
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else if (OPCODE_BSRF(op)) |
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addr = linux_regs->pc + 4 |
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+ linux_regs->regs[OPCODE_BSRF_REG(op)]; |
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/* JMP */ |
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else if (OPCODE_JMP(op)) |
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addr = linux_regs->regs[OPCODE_JMP_REG(op)]; |
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/* JSR */ |
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else if (OPCODE_JSR(op)) |
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addr = linux_regs->regs[OPCODE_JSR_REG(op)]; |
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/* RTS */ |
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else if (OPCODE_RTS(op)) |
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addr = linux_regs->pr; |
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/* RTE */ |
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else if (OPCODE_RTE(op)) |
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addr = linux_regs->regs[15]; |
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/* Other */ |
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else |
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addr = linux_regs->pc + instruction_size(op); |
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flush_icache_range(addr, addr + instruction_size(op)); |
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return (short *)addr; |
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} |
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/* |
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* Replace the instruction immediately after the current instruction |
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* (i.e. next in the expected flow of control) with a trap instruction, |
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* so that returning will cause only a single instruction to be executed. |
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* Note that this model is slightly broken for instructions with delay |
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* slots (e.g. B[TF]S, BSR, BRA etc), where both the branch and the |
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* instruction in the delay slot will be executed. |
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*/ |
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static unsigned long stepped_address; |
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static insn_size_t stepped_opcode; |
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static void do_single_step(struct pt_regs *linux_regs) |
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{ |
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/* Determine where the target instruction will send us to */ |
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unsigned short *addr = get_step_address(linux_regs); |
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stepped_address = (int)addr; |
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/* Replace it */ |
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stepped_opcode = __raw_readw((long)addr); |
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*addr = STEP_OPCODE; |
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/* Flush and return */ |
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flush_icache_range((long)addr, (long)addr + |
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instruction_size(stepped_opcode)); |
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} |
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/* Undo a single step */ |
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static void undo_single_step(struct pt_regs *linux_regs) |
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{ |
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/* If we have stepped, put back the old instruction */ |
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/* Use stepped_address in case we stopped elsewhere */ |
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if (stepped_opcode != 0) { |
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__raw_writew(stepped_opcode, stepped_address); |
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flush_icache_range(stepped_address, stepped_address + 2); |
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} |
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stepped_opcode = 0; |
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} |
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struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { |
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{ "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) }, |
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{ "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) }, |
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{ "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) }, |
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{ "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) }, |
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{ "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) }, |
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{ "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) }, |
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{ "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) }, |
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{ "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) }, |
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{ "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) }, |
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{ "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) }, |
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{ "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) }, |
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{ "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) }, |
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{ "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) }, |
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{ "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) }, |
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{ "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) }, |
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{ "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) }, |
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{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, pc) }, |
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{ "pr", GDB_SIZEOF_REG, offsetof(struct pt_regs, pr) }, |
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{ "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, sr) }, |
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{ "gbr", GDB_SIZEOF_REG, offsetof(struct pt_regs, gbr) }, |
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{ "mach", GDB_SIZEOF_REG, offsetof(struct pt_regs, mach) }, |
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{ "macl", GDB_SIZEOF_REG, offsetof(struct pt_regs, macl) }, |
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{ "vbr", GDB_SIZEOF_REG, -1 }, |
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}; |
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int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) |
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{ |
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if (regno < 0 || regno >= DBG_MAX_REG_NUM) |
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return -EINVAL; |
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if (dbg_reg_def[regno].offset != -1) |
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memcpy((void *)regs + dbg_reg_def[regno].offset, mem, |
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dbg_reg_def[regno].size); |
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return 0; |
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} |
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char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) |
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{ |
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if (regno >= DBG_MAX_REG_NUM || regno < 0) |
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return NULL; |
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if (dbg_reg_def[regno].size != -1) |
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memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, |
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dbg_reg_def[regno].size); |
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switch (regno) { |
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case GDB_VBR: |
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__asm__ __volatile__ ("stc vbr, %0" : "=r" (mem)); |
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break; |
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} |
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return dbg_reg_def[regno].name; |
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} |
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void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) |
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{ |
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struct pt_regs *thread_regs = task_pt_regs(p); |
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int reg; |
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/* Initialize to zero */ |
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for (reg = 0; reg < DBG_MAX_REG_NUM; reg++) |
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gdb_regs[reg] = 0; |
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/* |
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* Copy out GP regs 8 to 14. |
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* |
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* switch_to() relies on SR.RB toggling, so regs 0->7 are banked |
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* and need privileged instructions to get to. The r15 value we |
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* fetch from the thread info directly. |
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*/ |
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for (reg = GDB_R8; reg < GDB_R15; reg++) |
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gdb_regs[reg] = thread_regs->regs[reg]; |
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gdb_regs[GDB_R15] = p->thread.sp; |
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gdb_regs[GDB_PC] = p->thread.pc; |
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/* |
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* Additional registers we have context for |
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*/ |
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gdb_regs[GDB_PR] = thread_regs->pr; |
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gdb_regs[GDB_GBR] = thread_regs->gbr; |
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} |
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int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, |
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char *remcomInBuffer, char *remcomOutBuffer, |
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struct pt_regs *linux_regs) |
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{ |
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unsigned long addr; |
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char *ptr; |
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/* Undo any stepping we may have done */ |
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undo_single_step(linux_regs); |
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switch (remcomInBuffer[0]) { |
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case 'c': |
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case 's': |
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/* try to read optional parameter, pc unchanged if no parm */ |
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ptr = &remcomInBuffer[1]; |
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if (kgdb_hex2long(&ptr, &addr)) |
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linux_regs->pc = addr; |
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fallthrough; |
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case 'D': |
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case 'k': |
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atomic_set(&kgdb_cpu_doing_single_step, -1); |
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if (remcomInBuffer[0] == 's') { |
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do_single_step(linux_regs); |
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kgdb_single_step = 1; |
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atomic_set(&kgdb_cpu_doing_single_step, |
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raw_smp_processor_id()); |
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} |
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return 0; |
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} |
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/* this means that we do not want to exit from the handler: */ |
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return -1; |
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} |
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unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) |
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{ |
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if (exception == 60) |
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return instruction_pointer(regs) - 2; |
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return instruction_pointer(regs); |
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} |
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void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) |
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{ |
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regs->pc = ip; |
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} |
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/* |
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* The primary entry points for the kgdb debug trap table entries. |
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*/ |
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BUILD_TRAP_HANDLER(singlestep) |
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{ |
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unsigned long flags; |
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TRAP_HANDLER_DECL; |
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local_irq_save(flags); |
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regs->pc -= instruction_size(__raw_readw(regs->pc - 4)); |
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kgdb_handle_exception(0, SIGTRAP, 0, regs); |
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local_irq_restore(flags); |
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} |
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static int __kgdb_notify(struct die_args *args, unsigned long cmd) |
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{ |
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int ret; |
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switch (cmd) { |
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case DIE_BREAKPOINT: |
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/* |
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* This means a user thread is single stepping |
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* a system call which should be ignored |
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*/ |
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if (test_thread_flag(TIF_SINGLESTEP)) |
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return NOTIFY_DONE; |
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ret = kgdb_handle_exception(args->trapnr & 0xff, args->signr, |
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args->err, args->regs); |
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if (ret) |
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return NOTIFY_DONE; |
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break; |
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} |
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return NOTIFY_STOP; |
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} |
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static int |
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kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) |
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{ |
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unsigned long flags; |
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int ret; |
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local_irq_save(flags); |
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ret = __kgdb_notify(ptr, cmd); |
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local_irq_restore(flags); |
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return ret; |
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} |
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static struct notifier_block kgdb_notifier = { |
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.notifier_call = kgdb_notify, |
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/* |
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* Lowest-prio notifier priority, we want to be notified last: |
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*/ |
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.priority = -INT_MAX, |
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}; |
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int kgdb_arch_init(void) |
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{ |
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return register_die_notifier(&kgdb_notifier); |
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} |
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void kgdb_arch_exit(void) |
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{ |
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unregister_die_notifier(&kgdb_notifier); |
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} |
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const struct kgdb_arch arch_kgdb_ops = { |
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/* Breakpoint instruction: trapa #0x3c */ |
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#ifdef CONFIG_CPU_LITTLE_ENDIAN |
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.gdb_bpt_instr = { 0x3c, 0xc3 }, |
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#else |
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.gdb_bpt_instr = { 0xc3, 0x3c }, |
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#endif |
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};
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