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Thomas Gleixnerd2912cb2019-06-04 10:11:33 +02001// SPDX-License-Identifier: GPL-2.0-only
Mischa Jonkerf46121b2013-01-18 15:12:24 +05302/*
3 * kgdb support for ARC
4 *
5 * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
Mischa Jonkerf46121b2013-01-18 15:12:24 +05306 */
7
8#include <linux/kgdb.h>
Vineet Gupta1540c852013-03-07 16:47:23 +05309#include <linux/sched.h>
Ingo Molnar68db0cf2017-02-08 18:51:37 +010010#include <linux/sched/task_stack.h>
Mischa Jonkerf46121b2013-01-18 15:12:24 +053011#include <asm/disasm.h>
12#include <asm/cacheflush.h>
13
14static 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
37static 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
57void 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
63void 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
69void 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
77struct 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
84static 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
102static 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
110static 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
128int 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
144 case 'D':
145 case 'k':
146 atomic_set(&kgdb_cpu_doing_single_step, -1);
147
148 if (remcomInBuffer[0] == 's') {
149 do_single_step(regs);
150 atomic_set(&kgdb_cpu_doing_single_step,
151 smp_processor_id());
152 }
153
154 return 0;
155 }
156 return -1;
157}
158
Mischa Jonkerf46121b2013-01-18 15:12:24 +0530159int kgdb_arch_init(void)
160{
161 single_step_data.armed = 0;
162 return 0;
163}
164
Vineet Gupta38a9ff62013-06-12 15:13:40 +0530165void kgdb_trap(struct pt_regs *regs)
Mischa Jonkerf46121b2013-01-18 15:12:24 +0530166{
167 /* trap_s 3 is used for breakpoints that overwrite existing
168 * instructions, while trap_s 4 is used for compiled breakpoints.
169 *
170 * with trap_s 3 breakpoints the original instruction needs to be
171 * restored and continuation needs to start at the location of the
172 * breakpoint.
173 *
174 * with trap_s 4 (compiled) breakpoints, continuation needs to
175 * start after the breakpoint.
176 */
Vineet Gupta502a0c72013-06-11 18:56:54 +0530177 if (regs->ecr_param == 3)
Mischa Jonkerf46121b2013-01-18 15:12:24 +0530178 instruction_pointer(regs) -= BREAK_INSTR_SIZE;
179
180 kgdb_handle_exception(1, SIGTRAP, 0, regs);
181}
182
183void kgdb_arch_exit(void)
184{
185}
186
187void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
188{
189 instruction_pointer(regs) = ip;
190}
191
Douglas Anderson3cd99ac2018-12-04 19:38:26 -0800192void kgdb_call_nmi_hook(void *ignored)
Chen Gang3d01c1c2013-10-24 11:50:09 +0800193{
Douglas Anderson3cd99ac2018-12-04 19:38:26 -0800194 /* Default implementation passes get_irq_regs() but we don't */
Chen Gang3d01c1c2013-10-24 11:50:09 +0800195 kgdb_nmicallback(raw_smp_processor_id(), NULL);
196}
197
Christophe Leroycc028292018-12-06 20:07:40 +0000198const struct kgdb_arch arch_kgdb_ops = {
Mischa Jonkerf46121b2013-01-18 15:12:24 +0530199 /* 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};