1 // SPDX-License-Identifier: GPL-2.0-only 1
2 /*
3 * stacktrace.c : stacktracing APIs neede
4 * (wrappers over ARC dwa
5 *
6 * Copyright (C) 2004, 2007-2010, 2011-2012 Sy
7 *
8 * vineetg: aug 2009
9 * -Implemented CONFIG_STACKTRACE APIs, prima
10 * for displaying task's kernel mode call st
11 * -Iterator based approach to have single co
12 * needing unwinding, implement the logic in
13 * = which frame onwards to start capture
14 * = which frame to stop capturing (wchan
15 * = specifics of data structs where trac
16 *
17 * vineetg: March 2009
18 * -Implemented correct versions of thread_sa
19 *
20 * rajeshwarr: 2008
21 * -Initial implementation
22 */
23
24 #include <linux/ptrace.h>
25 #include <linux/export.h>
26 #include <linux/stacktrace.h>
27 #include <linux/kallsyms.h>
28 #include <linux/sched/debug.h>
29
30 #include <asm/arcregs.h>
31 #include <asm/unwind.h>
32 #include <asm/stacktrace.h>
33 #include <asm/switch_to.h>
34
35 /*--------------------------------------------
36 * Unwinder Iterator
37 *--------------------------------------------
38 */
39
40 #ifdef CONFIG_ARC_DW2_UNWIND
41
42 static int
43 seed_unwind_frame_info(struct task_struct *tsk
44 struct unwind_frame_inf
45 {
46 if (regs) {
47 /*
48 * Asynchronous unwinding of i
49 * - Just uses the pt_regs pa
50 */
51 frame_info->task = tsk;
52
53 frame_info->regs.r27 = regs->f
54 frame_info->regs.r28 = regs->s
55 frame_info->regs.r31 = regs->b
56 frame_info->regs.r63 = regs->r
57 frame_info->call_frame = 0;
58 } else if (tsk == NULL || tsk == curre
59 /*
60 * synchronous unwinding (e.g.
61 * - uses current values of S
62 */
63 unsigned long fp, sp, blink, r
64 frame_info->task = current;
65
66 __asm__ __volatile__(
67 "mov %0,r27\n\t"
68 "mov %1,r28\n\t"
69 "mov %2,r31\n\t"
70 "mov %3,r63\n\t"
71 : "=r"(fp), "=r"(sp),
72 );
73
74 frame_info->regs.r27 = fp;
75 frame_info->regs.r28 = sp;
76 frame_info->regs.r31 = blink;
77 frame_info->regs.r63 = ret;
78 frame_info->call_frame = 0;
79 } else {
80 /*
81 * Asynchronous unwinding of a
82 * - first ensure it is actua
83 * - if so, it will be in __s
84 * is safe-kept and BLINK a
85 */
86
87 if (task_is_running(tsk))
88 return -1;
89
90 frame_info->task = tsk;
91
92 frame_info->regs.r27 = TSK_K_F
93 frame_info->regs.r28 = TSK_K_E
94 frame_info->regs.r31 = TSK_K_B
95 frame_info->regs.r63 = (unsign
96
97 /* In the prologue of __switch
98 * and then SP is copied to FP
99 * but we didn't save FP. The
100 * state in previous frame.
101 * As a work around for this,
102 * and adjust SP accordingly.
103 * __switch_to macro is dwarf
104 * assembly code
105 */
106 frame_info->regs.r27 = 0;
107 frame_info->regs.r28 += 60;
108 frame_info->call_frame = 0;
109
110 }
111 return 0;
112 }
113
114 #endif
115
116 notrace noinline unsigned int
117 arc_unwind_core(struct task_struct *tsk, struc
118 int (*consumer_fn) (unsigned i
119 {
120 #ifdef CONFIG_ARC_DW2_UNWIND
121 int ret = 0, cnt = 0;
122 unsigned int address;
123 struct unwind_frame_info frame_info;
124
125 if (seed_unwind_frame_info(tsk, regs,
126 return 0;
127
128 while (1) {
129 address = UNW_PC(&frame_info);
130
131 if (!address || !__kernel_text
132 break;
133
134 if (consumer_fn(address, arg)
135 break;
136
137 ret = arc_unwind(&frame_info);
138 if (ret)
139 break;
140
141 frame_info.regs.r63 = frame_in
142
143 if (cnt++ > 128) {
144 printk("unwinder loopi
145 return 0;
146 }
147 }
148
149 return address; /* return the
150 #else
151 /* On ARC, only Dward based unwinder w
152 * not possible (-fno-omit-frame-point
153 * prologue is setup (callee regs save
154 * way around
155 */
156 pr_warn_once("CONFIG_ARC_DW2_UNWIND ne
157 return 0;
158
159 #endif
160 }
161
162 /*--------------------------------------------
163 * callbacks called by unwinder iterator to im
164 *
165 * The callback can return -1 to force the ite
166 * keeps going till the bottom-most frame.
167 *--------------------------------------------
168 */
169
170 /* Call-back which plugs into unwinding core t
171 * case of panic/OOPs/BUG etc
172 */
173 static int __print_sym(unsigned int address, v
174 {
175 const char *loglvl = arg;
176
177 printk("%s %pS\n", loglvl, (void *)ad
178 return 0;
179 }
180
181 #ifdef CONFIG_STACKTRACE
182
183 /* Call-back which plugs into unwinding core t
184 * traces needed by kernel on /proc/<pid>/stac
185 */
186 static int __collect_all(unsigned int address,
187 {
188 struct stack_trace *trace = arg;
189
190 if (trace->skip > 0)
191 trace->skip--;
192 else
193 trace->entries[trace->nr_entri
194
195 if (trace->nr_entries >= trace->max_en
196 return -1;
197
198 return 0;
199 }
200
201 static int __collect_all_but_sched(unsigned in
202 {
203 struct stack_trace *trace = arg;
204
205 if (in_sched_functions(address))
206 return 0;
207
208 if (trace->skip > 0)
209 trace->skip--;
210 else
211 trace->entries[trace->nr_entri
212
213 if (trace->nr_entries >= trace->max_en
214 return -1;
215
216 return 0;
217 }
218
219 #endif
220
221 static int __get_first_nonsched(unsigned int a
222 {
223 if (in_sched_functions(address))
224 return 0;
225
226 return -1;
227 }
228
229 /*--------------------------------------------
230 * APIs expected by various kerne
231 *--------------------------------------------
232 */
233
234 noinline void show_stacktrace(struct task_stru
235 const char *logl
236 {
237 printk("%s\nStack Trace:\n", loglvl);
238 arc_unwind_core(tsk, regs, __print_sym
239 }
240 EXPORT_SYMBOL(show_stacktrace);
241
242 /* Expected by sched Code */
243 void show_stack(struct task_struct *tsk, unsig
244 {
245 show_stacktrace(tsk, NULL, loglvl);
246 }
247
248 /* Another API expected by schedular, shows up
249 * Of course just returning schedule( ) would
250 * the function is not in schedular code
251 */
252 unsigned int __get_wchan(struct task_struct *t
253 {
254 return arc_unwind_core(tsk, NULL, __ge
255 }
256
257 #ifdef CONFIG_STACKTRACE
258
259 /*
260 * API required by CONFIG_STACKTRACE, CONFIG_L
261 * A typical use is when /proc/<pid>/stack is
262 */
263 void save_stack_trace_tsk(struct task_struct *
264 {
265 /* Assumes @tsk is sleeping so unwinds
266 arc_unwind_core(tsk, NULL, __collect_a
267 }
268
269 void save_stack_trace(struct stack_trace *trac
270 {
271 /* Pass NULL for task so it unwinds th
272 arc_unwind_core(NULL, NULL, __collect_
273 }
274 EXPORT_SYMBOL_GPL(save_stack_trace);
275 #endif
276
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