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 <linux/sched.h> 13 #include <asm/disasm.h> 14 #include <asm/cacheflush.h> 15 16 static void to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 17 struct callee_regs *cregs) 18 { 19 int regno; 20 21 for (regno = 0; regno <= 26; regno++) 22 gdb_regs[_R0 + regno] = get_reg(regno, kernel_regs, cregs); 23 24 for (regno = 27; regno < GDB_MAX_REGS; regno++) 25 gdb_regs[regno] = 0; 26 27 gdb_regs[_FP] = kernel_regs->fp; 28 gdb_regs[__SP] = kernel_regs->sp; 29 gdb_regs[_BLINK] = kernel_regs->blink; 30 gdb_regs[_RET] = kernel_regs->ret; 31 gdb_regs[_STATUS32] = kernel_regs->status32; 32 gdb_regs[_LP_COUNT] = kernel_regs->lp_count; 33 gdb_regs[_LP_END] = kernel_regs->lp_end; 34 gdb_regs[_LP_START] = kernel_regs->lp_start; 35 gdb_regs[_BTA] = kernel_regs->bta; 36 gdb_regs[_STOP_PC] = kernel_regs->ret; 37 } 38 39 static void from_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs, 40 struct callee_regs *cregs) 41 { 42 int regno; 43 44 for (regno = 0; regno <= 26; regno++) 45 set_reg(regno, gdb_regs[regno + _R0], kernel_regs, cregs); 46 47 kernel_regs->fp = gdb_regs[_FP]; 48 kernel_regs->sp = gdb_regs[__SP]; 49 kernel_regs->blink = gdb_regs[_BLINK]; 50 kernel_regs->ret = gdb_regs[_RET]; 51 kernel_regs->status32 = gdb_regs[_STATUS32]; 52 kernel_regs->lp_count = gdb_regs[_LP_COUNT]; 53 kernel_regs->lp_end = gdb_regs[_LP_END]; 54 kernel_regs->lp_start = gdb_regs[_LP_START]; 55 kernel_regs->bta = gdb_regs[_BTA]; 56 } 57 58 59 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 60 { 61 to_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 62 current->thread.callee_reg); 63 } 64 65 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *kernel_regs) 66 { 67 from_gdb_regs(gdb_regs, kernel_regs, (struct callee_regs *) 68 current->thread.callee_reg); 69 } 70 71 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, 72 struct task_struct *task) 73 { 74 if (task) 75 to_gdb_regs(gdb_regs, task_pt_regs(task), 76 (struct callee_regs *) task->thread.callee_reg); 77 } 78 79 struct single_step_data_t { 80 uint16_t opcode[2]; 81 unsigned long address[2]; 82 int is_branch; 83 int armed; 84 } single_step_data; 85 86 static void undo_single_step(struct pt_regs *regs) 87 { 88 if (single_step_data.armed) { 89 int i; 90 91 for (i = 0; i < (single_step_data.is_branch ? 2 : 1); i++) { 92 memcpy((void *) single_step_data.address[i], 93 &single_step_data.opcode[i], 94 BREAK_INSTR_SIZE); 95 96 flush_icache_range(single_step_data.address[i], 97 single_step_data.address[i] + 98 BREAK_INSTR_SIZE); 99 } 100 single_step_data.armed = 0; 101 } 102 } 103 104 static void place_trap(unsigned long address, void *save) 105 { 106 memcpy(save, (void *) address, BREAK_INSTR_SIZE); 107 memcpy((void *) address, &arch_kgdb_ops.gdb_bpt_instr, 108 BREAK_INSTR_SIZE); 109 flush_icache_range(address, address + BREAK_INSTR_SIZE); 110 } 111 112 static void do_single_step(struct pt_regs *regs) 113 { 114 single_step_data.is_branch = disasm_next_pc((unsigned long) 115 regs->ret, regs, (struct callee_regs *) 116 current->thread.callee_reg, 117 &single_step_data.address[0], 118 &single_step_data.address[1]); 119 120 place_trap(single_step_data.address[0], &single_step_data.opcode[0]); 121 122 if (single_step_data.is_branch) { 123 place_trap(single_step_data.address[1], 124 &single_step_data.opcode[1]); 125 } 126 127 single_step_data.armed++; 128 } 129 130 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 131 char *remcomInBuffer, char *remcomOutBuffer, 132 struct pt_regs *regs) 133 { 134 unsigned long addr; 135 char *ptr; 136 137 undo_single_step(regs); 138 139 switch (remcomInBuffer[0]) { 140 case 's': 141 case 'c': 142 ptr = &remcomInBuffer[1]; 143 if (kgdb_hex2long(&ptr, &addr)) 144 regs->ret = addr; 145 146 case 'D': 147 case 'k': 148 atomic_set(&kgdb_cpu_doing_single_step, -1); 149 150 if (remcomInBuffer[0] == 's') { 151 do_single_step(regs); 152 atomic_set(&kgdb_cpu_doing_single_step, 153 smp_processor_id()); 154 } 155 156 return 0; 157 } 158 return -1; 159 } 160 161 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 162 { 163 return instruction_pointer(regs); 164 } 165 166 int kgdb_arch_init(void) 167 { 168 single_step_data.armed = 0; 169 return 0; 170 } 171 172 void kgdb_trap(struct pt_regs *regs) 173 { 174 /* trap_s 3 is used for breakpoints that overwrite existing 175 * instructions, while trap_s 4 is used for compiled breakpoints. 176 * 177 * with trap_s 3 breakpoints the original instruction needs to be 178 * restored and continuation needs to start at the location of the 179 * breakpoint. 180 * 181 * with trap_s 4 (compiled) breakpoints, continuation needs to 182 * start after the breakpoint. 183 */ 184 if (regs->ecr_param == 3) 185 instruction_pointer(regs) -= BREAK_INSTR_SIZE; 186 187 kgdb_handle_exception(1, SIGTRAP, 0, regs); 188 } 189 190 void kgdb_arch_exit(void) 191 { 192 } 193 194 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 195 { 196 instruction_pointer(regs) = ip; 197 } 198 199 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