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, cregs: (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, cregs: (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 | cregs: (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(start: single_step_data.address[i], |
95 | end: 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(start: address, end: 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(address: single_step_data.address[0], save: &single_step_data.opcode[0]); |
119 | |
120 | if (single_step_data.is_branch) { |
121 | place_trap(address: single_step_data.address[1], |
122 | save: &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: &ptr, long_val: &addr)) |
142 | regs->ret = addr; |
143 | fallthrough; |
144 | |
145 | case 'D': |
146 | case 'k': |
147 | atomic_set(v: &kgdb_cpu_doing_single_step, i: -1); |
148 | |
149 | if (remcomInBuffer[0] == 's') { |
150 | do_single_step(regs); |
151 | atomic_set(v: &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(ex_vector: 1, SIGTRAP, err_code: 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 | |