diff options
Diffstat (limited to 'arch/riscv/kernel/kgdb.c')
| -rw-r--r-- | arch/riscv/kernel/kgdb.c | 390 |
1 files changed, 390 insertions, 0 deletions
diff --git a/arch/riscv/kernel/kgdb.c b/arch/riscv/kernel/kgdb.c new file mode 100644 index 000000000000..f16ade84a11f --- /dev/null +++ b/arch/riscv/kernel/kgdb.c @@ -0,0 +1,390 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 SiFive + */ + +#include <linux/ptrace.h> +#include <linux/kdebug.h> +#include <linux/bug.h> +#include <linux/kgdb.h> +#include <linux/irqflags.h> +#include <linux/string.h> +#include <asm/cacheflush.h> +#include <asm/gdb_xml.h> +#include <asm/parse_asm.h> + +enum { + NOT_KGDB_BREAK = 0, + KGDB_SW_BREAK, + KGDB_COMPILED_BREAK, + KGDB_SW_SINGLE_STEP +}; + +static unsigned long stepped_address; +static unsigned int stepped_opcode; + +#if __riscv_xlen == 32 +/* C.JAL is an RV32C-only instruction */ +DECLARE_INSN(c_jal, MATCH_C_JAL, MASK_C_JAL) +#else +#define is_c_jal_insn(opcode) 0 +#endif +DECLARE_INSN(jalr, MATCH_JALR, MASK_JALR) +DECLARE_INSN(jal, MATCH_JAL, MASK_JAL) +DECLARE_INSN(c_jr, MATCH_C_JR, MASK_C_JR) +DECLARE_INSN(c_jalr, MATCH_C_JALR, MASK_C_JALR) +DECLARE_INSN(c_j, MATCH_C_J, MASK_C_J) +DECLARE_INSN(beq, MATCH_BEQ, MASK_BEQ) +DECLARE_INSN(bne, MATCH_BNE, MASK_BNE) +DECLARE_INSN(blt, MATCH_BLT, MASK_BLT) +DECLARE_INSN(bge, MATCH_BGE, MASK_BGE) +DECLARE_INSN(bltu, MATCH_BLTU, MASK_BLTU) +DECLARE_INSN(bgeu, MATCH_BGEU, MASK_BGEU) +DECLARE_INSN(c_beqz, MATCH_C_BEQZ, MASK_C_BEQZ) +DECLARE_INSN(c_bnez, MATCH_C_BNEZ, MASK_C_BNEZ) +DECLARE_INSN(sret, MATCH_SRET, MASK_SRET) + +int decode_register_index(unsigned long opcode, int offset) +{ + return (opcode >> offset) & 0x1F; +} + +int decode_register_index_short(unsigned long opcode, int offset) +{ + return ((opcode >> offset) & 0x7) + 8; +} + +/* Calculate the new address for after a step */ +int get_step_address(struct pt_regs *regs, unsigned long *next_addr) +{ + unsigned long pc = regs->epc; + unsigned long *regs_ptr = (unsigned long *)regs; + unsigned int rs1_num, rs2_num; + int op_code; + + if (probe_kernel_address((void *)pc, op_code)) + return -EINVAL; + if ((op_code & __INSN_LENGTH_MASK) != __INSN_LENGTH_GE_32) { + if (is_c_jalr_insn(op_code) || is_c_jr_insn(op_code)) { + rs1_num = decode_register_index(op_code, RVC_C2_RS1_OPOFF); + *next_addr = regs_ptr[rs1_num]; + } else if (is_c_j_insn(op_code) || is_c_jal_insn(op_code)) { + *next_addr = EXTRACT_RVC_J_IMM(op_code) + pc; + } else if (is_c_beqz_insn(op_code)) { + rs1_num = decode_register_index_short(op_code, + RVC_C1_RS1_OPOFF); + if (!rs1_num || regs_ptr[rs1_num] == 0) + *next_addr = EXTRACT_RVC_B_IMM(op_code) + pc; + else + *next_addr = pc + 2; + } else if (is_c_bnez_insn(op_code)) { + rs1_num = + decode_register_index_short(op_code, RVC_C1_RS1_OPOFF); + if (rs1_num && regs_ptr[rs1_num] != 0) + *next_addr = EXTRACT_RVC_B_IMM(op_code) + pc; + else + *next_addr = pc + 2; + } else { + *next_addr = pc + 2; + } + } else { + if ((op_code & __INSN_OPCODE_MASK) == __INSN_BRANCH_OPCODE) { + bool result = false; + long imm = EXTRACT_BTYPE_IMM(op_code); + unsigned long rs1_val = 0, rs2_val = 0; + + rs1_num = decode_register_index(op_code, RVG_RS1_OPOFF); + rs2_num = decode_register_index(op_code, RVG_RS2_OPOFF); + if (rs1_num) + rs1_val = regs_ptr[rs1_num]; + if (rs2_num) + rs2_val = regs_ptr[rs2_num]; + + if (is_beq_insn(op_code)) + result = (rs1_val == rs2_val) ? true : false; + else if (is_bne_insn(op_code)) + result = (rs1_val != rs2_val) ? true : false; + else if (is_blt_insn(op_code)) + result = + ((long)rs1_val < + (long)rs2_val) ? true : false; + else if (is_bge_insn(op_code)) + result = + ((long)rs1_val >= + (long)rs2_val) ? true : false; + else if (is_bltu_insn(op_code)) + result = (rs1_val < rs2_val) ? true : false; + else if (is_bgeu_insn(op_code)) + result = (rs1_val >= rs2_val) ? true : false; + if (result) + *next_addr = imm + pc; + else + *next_addr = pc + 4; + } else if (is_jal_insn(op_code)) { + *next_addr = EXTRACT_JTYPE_IMM(op_code) + pc; + } else if (is_jalr_insn(op_code)) { + rs1_num = decode_register_index(op_code, RVG_RS1_OPOFF); + if (rs1_num) + *next_addr = ((unsigned long *)regs)[rs1_num]; + *next_addr += EXTRACT_ITYPE_IMM(op_code); + } else if (is_sret_insn(op_code)) { + *next_addr = pc; + } else { + *next_addr = pc + 4; + } + } + return 0; +} + +int do_single_step(struct pt_regs *regs) +{ + /* Determine where the target instruction will send us to */ + unsigned long addr = 0; + int error = get_step_address(regs, &addr); + + if (error) + return error; + + /* Store the op code in the stepped address */ + error = probe_kernel_address((void *)addr, stepped_opcode); + if (error) + return error; + + stepped_address = addr; + + /* Replace the op code with the break instruction */ + error = probe_kernel_write((void *)stepped_address, + arch_kgdb_ops.gdb_bpt_instr, + BREAK_INSTR_SIZE); + /* Flush and return */ + if (!error) { + flush_icache_range(addr, addr + BREAK_INSTR_SIZE); + kgdb_single_step = 1; + atomic_set(&kgdb_cpu_doing_single_step, + raw_smp_processor_id()); + } else { + stepped_address = 0; + stepped_opcode = 0; + } + return error; +} + +/* Undo a single step */ +static void undo_single_step(struct pt_regs *regs) +{ + if (stepped_opcode != 0) { + probe_kernel_write((void *)stepped_address, + (void *)&stepped_opcode, BREAK_INSTR_SIZE); + flush_icache_range(stepped_address, + stepped_address + BREAK_INSTR_SIZE); + } + stepped_address = 0; + stepped_opcode = 0; + kgdb_single_step = 0; + atomic_set(&kgdb_cpu_doing_single_step, -1); +} + +struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { + {DBG_REG_ZERO, GDB_SIZEOF_REG, -1}, + {DBG_REG_RA, GDB_SIZEOF_REG, offsetof(struct pt_regs, ra)}, + {DBG_REG_SP, GDB_SIZEOF_REG, offsetof(struct pt_regs, sp)}, + {DBG_REG_GP, GDB_SIZEOF_REG, offsetof(struct pt_regs, gp)}, + {DBG_REG_TP, GDB_SIZEOF_REG, offsetof(struct pt_regs, tp)}, + {DBG_REG_T0, GDB_SIZEOF_REG, offsetof(struct pt_regs, t0)}, + {DBG_REG_T1, GDB_SIZEOF_REG, offsetof(struct pt_regs, t1)}, + {DBG_REG_T2, GDB_SIZEOF_REG, offsetof(struct pt_regs, t2)}, + {DBG_REG_FP, GDB_SIZEOF_REG, offsetof(struct pt_regs, s0)}, + {DBG_REG_S1, GDB_SIZEOF_REG, offsetof(struct pt_regs, a1)}, + {DBG_REG_A0, GDB_SIZEOF_REG, offsetof(struct pt_regs, a0)}, + {DBG_REG_A1, GDB_SIZEOF_REG, offsetof(struct pt_regs, a1)}, + {DBG_REG_A2, GDB_SIZEOF_REG, offsetof(struct pt_regs, a2)}, + {DBG_REG_A3, GDB_SIZEOF_REG, offsetof(struct pt_regs, a3)}, + {DBG_REG_A4, GDB_SIZEOF_REG, offsetof(struct pt_regs, a4)}, + {DBG_REG_A5, GDB_SIZEOF_REG, offsetof(struct pt_regs, a5)}, + {DBG_REG_A6, GDB_SIZEOF_REG, offsetof(struct pt_regs, a6)}, + {DBG_REG_A7, GDB_SIZEOF_REG, offsetof(struct pt_regs, a7)}, + {DBG_REG_S2, GDB_SIZEOF_REG, offsetof(struct pt_regs, s2)}, + {DBG_REG_S3, GDB_SIZEOF_REG, offsetof(struct pt_regs, s3)}, + {DBG_REG_S4, GDB_SIZEOF_REG, offsetof(struct pt_regs, s4)}, + {DBG_REG_S5, GDB_SIZEOF_REG, offsetof(struct pt_regs, s5)}, + {DBG_REG_S6, GDB_SIZEOF_REG, offsetof(struct pt_regs, s6)}, + {DBG_REG_S7, GDB_SIZEOF_REG, offsetof(struct pt_regs, s7)}, + {DBG_REG_S8, GDB_SIZEOF_REG, offsetof(struct pt_regs, s8)}, + {DBG_REG_S9, GDB_SIZEOF_REG, offsetof(struct pt_regs, s9)}, + {DBG_REG_S10, GDB_SIZEOF_REG, offsetof(struct pt_regs, s10)}, + {DBG_REG_S11, GDB_SIZEOF_REG, offsetof(struct pt_regs, s11)}, + {DBG_REG_T3, GDB_SIZEOF_REG, offsetof(struct pt_regs, t3)}, + {DBG_REG_T4, GDB_SIZEOF_REG, offsetof(struct pt_regs, t4)}, + {DBG_REG_T5, GDB_SIZEOF_REG, offsetof(struct pt_regs, t5)}, + {DBG_REG_T6, GDB_SIZEOF_REG, offsetof(struct pt_regs, t6)}, + {DBG_REG_EPC, GDB_SIZEOF_REG, offsetof(struct pt_regs, epc)}, + {DBG_REG_STATUS, GDB_SIZEOF_REG, offsetof(struct pt_regs, status)}, + {DBG_REG_BADADDR, GDB_SIZEOF_REG, offsetof(struct pt_regs, badaddr)}, + {DBG_REG_CAUSE, GDB_SIZEOF_REG, offsetof(struct pt_regs, cause)}, +}; + +char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) +{ + if (regno >= DBG_MAX_REG_NUM || regno < 0) + return NULL; + + if (dbg_reg_def[regno].offset != -1) + memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, + dbg_reg_def[regno].size); + else + memset(mem, 0, dbg_reg_def[regno].size); + return dbg_reg_def[regno].name; +} + +int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) +{ + if (regno >= DBG_MAX_REG_NUM || regno < 0) + return -EINVAL; + + if (dbg_reg_def[regno].offset != -1) + memcpy((void *)regs + dbg_reg_def[regno].offset, mem, + dbg_reg_def[regno].size); + return 0; +} + +void +sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) +{ + /* Initialize to zero */ + memset((char *)gdb_regs, 0, NUMREGBYTES); + + gdb_regs[DBG_REG_SP_OFF] = task->thread.sp; + gdb_regs[DBG_REG_FP_OFF] = task->thread.s[0]; + gdb_regs[DBG_REG_S1_OFF] = task->thread.s[1]; + gdb_regs[DBG_REG_S2_OFF] = task->thread.s[2]; + gdb_regs[DBG_REG_S3_OFF] = task->thread.s[3]; + gdb_regs[DBG_REG_S4_OFF] = task->thread.s[4]; + gdb_regs[DBG_REG_S5_OFF] = task->thread.s[5]; + gdb_regs[DBG_REG_S6_OFF] = task->thread.s[6]; + gdb_regs[DBG_REG_S7_OFF] = task->thread.s[7]; + gdb_regs[DBG_REG_S8_OFF] = task->thread.s[8]; + gdb_regs[DBG_REG_S9_OFF] = task->thread.s[10]; + gdb_regs[DBG_REG_S10_OFF] = task->thread.s[11]; + gdb_regs[DBG_REG_EPC_OFF] = task->thread.ra; +} + +void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) +{ + regs->epc = pc; +} + +void kgdb_arch_handle_qxfer_pkt(char *remcom_in_buffer, + char *remcom_out_buffer) +{ + if (!strncmp(remcom_in_buffer, gdb_xfer_read_target, + sizeof(gdb_xfer_read_target))) + strcpy(remcom_out_buffer, riscv_gdb_stub_target_desc); + else if (!strncmp(remcom_in_buffer, gdb_xfer_read_cpuxml, + sizeof(gdb_xfer_read_cpuxml))) + strcpy(remcom_out_buffer, riscv_gdb_stub_cpuxml); +} + +static inline void kgdb_arch_update_addr(struct pt_regs *regs, + char *remcom_in_buffer) +{ + unsigned long addr; + char *ptr; + + ptr = &remcom_in_buffer[1]; + if (kgdb_hex2long(&ptr, &addr)) + regs->epc = addr; +} + +int kgdb_arch_handle_exception(int vector, int signo, int err_code, + char *remcom_in_buffer, char *remcom_out_buffer, + struct pt_regs *regs) +{ + int err = 0; + + undo_single_step(regs); + + switch (remcom_in_buffer[0]) { + case 'c': + case 'D': + case 'k': + if (remcom_in_buffer[0] == 'c') + kgdb_arch_update_addr(regs, remcom_in_buffer); + break; + case 's': + kgdb_arch_update_addr(regs, remcom_in_buffer); + err = do_single_step(regs); + break; + default: + err = -1; + } + return err; +} + +int kgdb_riscv_kgdbbreak(unsigned long addr) +{ + if (stepped_address == addr) + return KGDB_SW_SINGLE_STEP; + if (atomic_read(&kgdb_setting_breakpoint)) + if (addr == (unsigned long)&kgdb_compiled_break) + return KGDB_COMPILED_BREAK; + + return kgdb_has_hit_break(addr); +} + +static int kgdb_riscv_notify(struct notifier_block *self, unsigned long cmd, + void *ptr) +{ + struct die_args *args = (struct die_args *)ptr; + struct pt_regs *regs = args->regs; + unsigned long flags; + int type; + + if (user_mode(regs)) + return NOTIFY_DONE; + + type = kgdb_riscv_kgdbbreak(regs->epc); + if (type == NOT_KGDB_BREAK && cmd == DIE_TRAP) + return NOTIFY_DONE; + + local_irq_save(flags); + + if (kgdb_handle_exception(type == KGDB_SW_SINGLE_STEP ? 0 : 1, + args->signr, cmd, regs)) + return NOTIFY_DONE; + + if (type == KGDB_COMPILED_BREAK) + regs->epc += 4; + + local_irq_restore(flags); + + return NOTIFY_STOP; +} + +static struct notifier_block kgdb_notifier = { + .notifier_call = kgdb_riscv_notify, +}; + +int kgdb_arch_init(void) +{ + register_die_notifier(&kgdb_notifier); + + return 0; +} + +void kgdb_arch_exit(void) +{ + unregister_die_notifier(&kgdb_notifier); +} + +/* + * Global data + */ +#ifdef CONFIG_RISCV_ISA_C +const struct kgdb_arch arch_kgdb_ops = { + .gdb_bpt_instr = {0x02, 0x90}, /* c.ebreak */ +}; +#else +const struct kgdb_arch arch_kgdb_ops = { + .gdb_bpt_instr = {0x73, 0x00, 0x10, 0x00}, /* ebreak */ +}; +#endif |