1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * kgdb support for ARC 4 * 5 * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com) 6 */ 7 8 #include <linux/kgdb.h> 9 #include <linux/sched.h> 10 #include <linux/sched/task_stack.h> 11 #include <asm/disasm.h> 12 #include <asm/cacheflush.h> 13 14 static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 15 struct callee_regs *cregs) 16 { 17 int regno; 18 19 for (regno = 0; regno <= 26; regno++) 20 gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs); 21 22 for (regno = 27; regno < GDB_MAX_REGS; regno++) 23 gdb_regs[regno] = 0; 24 25 gdb_regs[_FP] = kernel_regs->fp; 26 gdb_regs[__SP] = kernel_regs->sp; 27 gdb_regs[_BLINK] = kernel_regs->blink; 28 gdb_regs[_RET] = kernel_regs->ret; 29 gdb_regs[_STATUS32] = kernel_regs->status32; 30 gdb_regs[_LP_COUNT] = kernel_regs->lp_count; 31 gdb_regs[_LP_END] = kernel_regs->lp_end; 32 gdb_regs[_LP_START] = kernel_regs->lp_start; 33 gdb_regs[_BTA] = kernel_regs->bta; 34 gdb_regs[_STOP_PC] = kernel_regs->ret; 35 } 36 37 static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 38 struct callee_regs *cregs) 39 { 40 int regno; 41 42 for (regno = 0; regno <= 26; regno++) 43 set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs); 44 45 kernel_regs->fp = gdb_regs[_FP]; 46 kernel_regs->sp = gdb_regs[__SP]; 47 kernel_regs->blink = gdb_regs[_BLINK]; 48 kernel_regs->ret = gdb_regs[_RET]; 49 kernel_regs->status32 = gdb_regs[_STATUS32]; 50 kernel_regs->lp_count = gdb_regs[_LP_COUNT]; 51 kernel_regs->lp_end = gdb_regs[_LP_END]; 52 kernel_regs->lp_start = gdb_regs[_LP_START]; 53 kernel_regs->bta = gdb_regs[_BTA]; 54 } 55 56 57 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 58 { 59 to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 60 current->thread.callee_reg); 61 } 62 63 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 64 { 65 from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 66 current->thread.callee_reg); 67 } 68 69 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, 70 struct task_struct *task) 71 { 72 if (task) 73 to_gdb_regs(gdb_regs, task_pt_regs(task), 74 (struct callee_regs *) task->thread.callee_reg); 75 } 76 77 struct single_step_data_t { 78 uint16_t opcode[2]; 79 unsigned long address[2]; 80 int is_branch; 81 int armed; 82 } single_step_data; 83 84 static void undo_single_step(struct pt_regs *regs) 85 { 86 if (single_step_data.armed) { 87 int i; 88 89 for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) { 90 memcpy((void *) single_step_data.address[i], 91 &single_step_data.opcode[i], 92 BREAK_INSTR_SIZE); 93 94 flush_icache_range(single_step_data.address[i], 95 single_step_data.address[i] + 96 BREAK_INSTR_SIZE); 97 } 98 single_step_data.armed = 0; 99 } 100 } 101 102 static void place_trap(unsigned long address, void *save) 103 { 104 memcpy(save, (void *) address, BREAK_INSTR_SIZE); 105 memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr, 106 BREAK_INSTR_SIZE); 107 flush_icache_range(address, address + BREAK_INSTR_SIZE); 108 } 109 110 static void do_single_step(struct pt_regs *regs) 111 { 112 single_step_data.is_branch = disasm_next_pc((unsigned long) 113 regs->ret, regs, (struct callee_regs *) 114 current->thread.callee_reg, 115 &single_step_data.address[0], 116 &single_step_data.address[1]); 117 118 place_trap(single_step_data.address[0], &single_step_data.opcode[0]); 119 120 if (single_step_data.is_branch) { 121 place_trap(single_step_data.address[1], 122 &single_step_data.opcode[1]); 123 } 124 125 single_step_data.armed++; 126 } 127 128 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 129 char *remcomInBuffer, char *remcomOutBuffer, 130 struct pt_regs *regs) 131 { 132 unsigned long addr; 133 char *ptr; 134 135 undo_single_step(regs); 136 137 switch (remcomInBuffer[0]) { 138 case 's': 139 case 'c': 140 ptr = &remcomInBuffer[1]; 141 if (kgdb_hex2long(&ptr, &addr)) 142 regs->ret = addr; 143 fallthrough; 144 145 case 'D': 146 case 'k': 147 atomic_set(&kgdb_cpu_doing_single_step, -1); 148 149 if (remcomInBuffer[0] == 's') { 150 do_single_step(regs); 151 atomic_set(&kgdb_cpu_doing_single_step, 152 smp_processor_id()); 153 } 154 155 return 0; 156 } 157 return -1; 158 } 159 160 int kgdb_arch_init(void) 161 { 162 single_step_data.armed = 0; 163 return 0; 164 } 165 166 void kgdb_trap(struct pt_regs *regs) 167 { 168 /* trap_s 3 is used for breakpoints that overwrite existing 169 * instructions, while trap_s 4 is used for compiled breakpoints. 170 * 171 * with trap_s 3 breakpoints the original instruction needs to be 172 * restored and continuation needs to start at the location of the 173 * breakpoint. 174 * 175 * with trap_s 4 (compiled) breakpoints, continuation needs to 176 * start after the breakpoint. 177 */ 178 if (regs->ecr.param == 3) 179 instruction_pointer(regs) -= BREAK_INSTR_SIZE; 180 181 kgdb_handle_exception(1, SIGTRAP, 0, regs); 182 } 183 184 void kgdb_arch_exit(void) 185 { 186 } 187 188 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 189 { 190 instruction_pointer(regs) = ip; 191 } 192 193 void kgdb_call_nmi_hook(void *ignored) 194 { 195 /* Default implementation passes get_irq_regs() but we don't */ 196 kgdb_nmicallback(raw_smp_processor_id(), NULL); 197 } 198 199 const struct kgdb_arch arch_kgdb_ops = { 200 /* breakpoint instruction: TRAP_S 0x3 */ 201 #ifdef CONFIG_CPU_BIG_ENDIAN 202 .gdb_bpt_instr = {0x78, 0x7e}, 203 #else 204 .gdb_bpt_instr = {0x7e, 0x78}, 205 #endif 206 }; 207