1 /* 2 * kgdb support for ARC 3 * 4 * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com) 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11 #include <linux/kgdb.h> 12 #include <asm/disasm.h> 13 #include <asm/cacheflush.h> 14 15 static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 16 struct callee_regs *cregs) 17 { 18 int regno; 19 20 for (regno = 0; regno <= 26; regno++) 21 gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs); 22 23 for (regno = 27; regno < GDB_MAX_REGS; regno++) 24 gdb_regs[regno] = 0; 25 26 gdb_regs[_FP] = kernel_regs->fp; 27 gdb_regs[__SP] = kernel_regs->sp; 28 gdb_regs[_BLINK] = kernel_regs->blink; 29 gdb_regs[_RET] = kernel_regs->ret; 30 gdb_regs[_STATUS32] = kernel_regs->status32; 31 gdb_regs[_LP_COUNT] = kernel_regs->lp_count; 32 gdb_regs[_LP_END] = kernel_regs->lp_end; 33 gdb_regs[_LP_START] = kernel_regs->lp_start; 34 gdb_regs[_BTA] = kernel_regs->bta; 35 gdb_regs[_STOP_PC] = kernel_regs->ret; 36 } 37 38 static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 39 struct callee_regs *cregs) 40 { 41 int regno; 42 43 for (regno = 0; regno <= 26; regno++) 44 set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs); 45 46 kernel_regs->fp = gdb_regs[_FP]; 47 kernel_regs->sp = gdb_regs[__SP]; 48 kernel_regs->blink = gdb_regs[_BLINK]; 49 kernel_regs->ret = gdb_regs[_RET]; 50 kernel_regs->status32 = gdb_regs[_STATUS32]; 51 kernel_regs->lp_count = gdb_regs[_LP_COUNT]; 52 kernel_regs->lp_end = gdb_regs[_LP_END]; 53 kernel_regs->lp_start = gdb_regs[_LP_START]; 54 kernel_regs->bta = gdb_regs[_BTA]; 55 } 56 57 58 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 59 { 60 to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 61 current->thread.callee_reg); 62 } 63 64 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 65 { 66 from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 67 current->thread.callee_reg); 68 } 69 70 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, 71 struct task_struct *task) 72 { 73 if (task) 74 to_gdb_regs(gdb_regs, task_pt_regs(task), 75 (struct callee_regs *) task->thread.callee_reg); 76 } 77 78 struct single_step_data_t { 79 uint16_t opcode[2]; 80 unsigned long address[2]; 81 int is_branch; 82 int armed; 83 } single_step_data; 84 85 static void undo_single_step(struct pt_regs *regs) 86 { 87 if (single_step_data.armed) { 88 int i; 89 90 for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) { 91 memcpy((void *) single_step_data.address[i], 92 &single_step_data.opcode[i], 93 BREAK_INSTR_SIZE); 94 95 flush_icache_range(single_step_data.address[i], 96 single_step_data.address[i] + 97 BREAK_INSTR_SIZE); 98 } 99 single_step_data.armed = 0; 100 } 101 } 102 103 static void place_trap(unsigned long address, void *save) 104 { 105 memcpy(save, (void *) address, BREAK_INSTR_SIZE); 106 memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr, 107 BREAK_INSTR_SIZE); 108 flush_icache_range(address, address + BREAK_INSTR_SIZE); 109 } 110 111 static void do_single_step(struct pt_regs *regs) 112 { 113 single_step_data.is_branch = disasm_next_pc((unsigned long) 114 regs->ret, regs, (struct callee_regs *) 115 current->thread.callee_reg, 116 &single_step_data.address[0], 117 &single_step_data.address[1]); 118 119 place_trap(single_step_data.address[0], &single_step_data.opcode[0]); 120 121 if (single_step_data.is_branch) { 122 place_trap(single_step_data.address[1], 123 &single_step_data.opcode[1]); 124 } 125 126 single_step_data.armed++; 127 } 128 129 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 130 char *remcomInBuffer, char *remcomOutBuffer, 131 struct pt_regs *regs) 132 { 133 unsigned long addr; 134 char *ptr; 135 136 undo_single_step(regs); 137 138 switch (remcomInBuffer[0]) { 139 case 's': 140 case 'c': 141 ptr = &remcomInBuffer[1]; 142 if (kgdb_hex2long(&ptr, &addr)) 143 regs->ret = addr; 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 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 161 { 162 return instruction_pointer(regs); 163 } 164 165 int kgdb_arch_init(void) 166 { 167 single_step_data.armed = 0; 168 return 0; 169 } 170 171 void kgdb_trap(struct pt_regs *regs, int param) 172 { 173 /* trap_s 3 is used for breakpoints that overwrite existing 174 * instructions, while trap_s 4 is used for compiled breakpoints. 175 * 176 * with trap_s 3 breakpoints the original instruction needs to be 177 * restored and continuation needs to start at the location of the 178 * breakpoint. 179 * 180 * with trap_s 4 (compiled) breakpoints, continuation needs to 181 * start after the breakpoint. 182 */ 183 if (param == 3) 184 instruction_pointer(regs) -= BREAK_INSTR_SIZE; 185 186 kgdb_handle_exception(1, SIGTRAP, 0, regs); 187 } 188 189 void kgdb_arch_exit(void) 190 { 191 } 192 193 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 194 { 195 instruction_pointer(regs) = ip; 196 } 197 198 struct kgdb_arch arch_kgdb_ops = { 199 /* breakpoint instruction: TRAP_S 0x3 */ 200 #ifdef CONFIG_CPU_BIG_ENDIAN 201 .gdb_bpt_instr = {0x78, 0x7e}, 202 #else 203 .gdb_bpt_instr = {0x7e, 0x78}, 204 #endif 205 }; 206