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1/*
2 * stacktrace.c : stacktracing APIs needed by rest of kernel
3 * (wrappers over ARC dwarf based unwinder)
4 *
5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * vineetg: aug 2009
12 * -Implemented CONFIG_STACKTRACE APIs, primarily save_stack_trace_tsk( )
13 * for displaying task's kernel mode call stack in /proc/<pid>/stack
14 * -Iterator based approach to have single copy of unwinding core and APIs
15 * needing unwinding, implement the logic in iterator regarding:
16 * = which frame onwards to start capture
17 * = which frame to stop capturing (wchan)
18 * = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)
19 *
20 * vineetg: March 2009
21 * -Implemented correct versions of thread_saved_pc() and get_wchan()
22 *
23 * rajeshwarr: 2008
24 * -Initial implementation
25 */
26
27#include <linux/ptrace.h>
28#include <linux/export.h>
29#include <linux/stacktrace.h>
30#include <linux/kallsyms.h>
31#include <asm/arcregs.h>
32#include <asm/unwind.h>
33#include <asm/switch_to.h>
34
35/*-------------------------------------------------------------------------
36 * Unwinder Iterator
37 *-------------------------------------------------------------------------
38 */
39
40#ifdef CONFIG_ARC_DW2_UNWIND
41
42static void seed_unwind_frame_info(struct task_struct *tsk,
43 struct pt_regs *regs,
44 struct unwind_frame_info *frame_info)
45{
46 /*
47 * synchronous unwinding (e.g. dump_stack)
48 * - uses current values of SP and friends
49 */
50 if (tsk == NULL && regs == NULL) {
51 unsigned long fp, sp, blink, ret;
52 frame_info->task = current;
53
54 __asm__ __volatile__(
55 "mov %0,r27\n\t"
56 "mov %1,r28\n\t"
57 "mov %2,r31\n\t"
58 "mov %3,r63\n\t"
59 : "=r"(fp), "=r"(sp), "=r"(blink), "=r"(ret)
60 );
61
62 frame_info->regs.r27 = fp;
63 frame_info->regs.r28 = sp;
64 frame_info->regs.r31 = blink;
65 frame_info->regs.r63 = ret;
66 frame_info->call_frame = 0;
67 } else if (regs == NULL) {
68 /*
69 * Asynchronous unwinding of sleeping task
70 * - Gets SP etc from task's pt_regs (saved bottom of kernel
71 * mode stack of task)
72 */
73
74 frame_info->task = tsk;
75
76 frame_info->regs.r27 = TSK_K_FP(tsk);
77 frame_info->regs.r28 = TSK_K_ESP(tsk);
78 frame_info->regs.r31 = TSK_K_BLINK(tsk);
79 frame_info->regs.r63 = (unsigned int)__switch_to;
80
81 /* In the prologue of __switch_to, first FP is saved on stack
82 * and then SP is copied to FP. Dwarf assumes cfa as FP based
83 * but we didn't save FP. The value retrieved above is FP's
84 * state in previous frame.
85 * As a work around for this, we unwind from __switch_to start
86 * and adjust SP accordingly. The other limitation is that
87 * __switch_to macro is dwarf rules are not generated for inline
88 * assembly code
89 */
90 frame_info->regs.r27 = 0;
91 frame_info->regs.r28 += 60;
92 frame_info->call_frame = 0;
93
94 } else {
95 /*
96 * Asynchronous unwinding of intr/exception
97 * - Just uses the pt_regs passed
98 */
99 frame_info->task = tsk;
100
101 frame_info->regs.r27 = regs->fp;
102 frame_info->regs.r28 = regs->sp;
103 frame_info->regs.r31 = regs->blink;
104 frame_info->regs.r63 = regs->ret;
105 frame_info->call_frame = 0;
106 }
107}
108
109#endif
110
111notrace noinline unsigned int
112arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
113 int (*consumer_fn) (unsigned int, void *), void *arg)
114{
115#ifdef CONFIG_ARC_DW2_UNWIND
116 int ret = 0;
117 unsigned int address;
118 struct unwind_frame_info frame_info;
119
120 seed_unwind_frame_info(tsk, regs, &frame_info);
121
122 while (1) {
123 address = UNW_PC(&frame_info);
124
125 if (!address || !__kernel_text_address(address))
126 break;
127
128 if (consumer_fn(address, arg) == -1)
129 break;
130
131 ret = arc_unwind(&frame_info);
132 if (ret)
133 break;
134
135 frame_info.regs.r63 = frame_info.regs.r31;
136 }
137
138 return address; /* return the last address it saw */
139#else
140 /* On ARC, only Dward based unwinder works. fp based backtracing is
141 * not possible (-fno-omit-frame-pointer) because of the way function
142 * prelogue is setup (callee regs saved and then fp set and not other
143 * way around
144 */
145 pr_warn_once("CONFIG_ARC_DW2_UNWIND needs to be enabled\n");
146 return 0;
147
148#endif
149}
150
151/*-------------------------------------------------------------------------
152 * callbacks called by unwinder iterator to implement kernel APIs
153 *
154 * The callback can return -1 to force the iterator to stop, which by default
155 * keeps going till the bottom-most frame.
156 *-------------------------------------------------------------------------
157 */
158
159/* Call-back which plugs into unwinding core to dump the stack in
160 * case of panic/OOPs/BUG etc
161 */
162static int __print_sym(unsigned int address, void *unused)
163{
164 __print_symbol(" %s\n", address);
165 return 0;
166}
167
168#ifdef CONFIG_STACKTRACE
169
170/* Call-back which plugs into unwinding core to capture the
171 * traces needed by kernel on /proc/<pid>/stack
172 */
173static int __collect_all(unsigned int address, void *arg)
174{
175 struct stack_trace *trace = arg;
176
177 if (trace->skip > 0)
178 trace->skip--;
179 else
180 trace->entries[trace->nr_entries++] = address;
181
182 if (trace->nr_entries >= trace->max_entries)
183 return -1;
184
185 return 0;
186}
187
188static int __collect_all_but_sched(unsigned int address, void *arg)
189{
190 struct stack_trace *trace = arg;
191
192 if (in_sched_functions(address))
193 return 0;
194
195 if (trace->skip > 0)
196 trace->skip--;
197 else
198 trace->entries[trace->nr_entries++] = address;
199
200 if (trace->nr_entries >= trace->max_entries)
201 return -1;
202
203 return 0;
204}
205
206#endif
207
208static int __get_first_nonsched(unsigned int address, void *unused)
209{
210 if (in_sched_functions(address))
211 return 0;
212
213 return -1;
214}
215
216/*-------------------------------------------------------------------------
217 * APIs expected by various kernel sub-systems
218 *-------------------------------------------------------------------------
219 */
220
221noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs)
222{
223 pr_info("\nStack Trace:\n");
224 arc_unwind_core(tsk, regs, __print_sym, NULL);
225}
226EXPORT_SYMBOL(show_stacktrace);
227
228/* Expected by sched Code */
229void show_stack(struct task_struct *tsk, unsigned long *sp)
230{
231 show_stacktrace(tsk, NULL);
232}
233
234/* Another API expected by schedular, shows up in "ps" as Wait Channel
235 * Of course just returning schedule( ) would be pointless so unwind until
236 * the function is not in schedular code
237 */
238unsigned int get_wchan(struct task_struct *tsk)
239{
240 return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);
241}
242
243#ifdef CONFIG_STACKTRACE
244
245/*
246 * API required by CONFIG_STACKTRACE, CONFIG_LATENCYTOP.
247 * A typical use is when /proc/<pid>/stack is queried by userland
248 */
249void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
250{
251 /* Assumes @tsk is sleeping so unwinds from __switch_to */
252 arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace);
253}
254
255void save_stack_trace(struct stack_trace *trace)
256{
257 /* Pass NULL for task so it unwinds the current call frame */
258 arc_unwind_core(NULL, NULL, __collect_all, trace);
259}
260EXPORT_SYMBOL_GPL(save_stack_trace);
261#endif
1/*
2 * stacktrace.c : stacktracing APIs needed by rest of kernel
3 * (wrappers over ARC dwarf based unwinder)
4 *
5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * vineetg: aug 2009
12 * -Implemented CONFIG_STACKTRACE APIs, primarily save_stack_trace_tsk( )
13 * for displaying task's kernel mode call stack in /proc/<pid>/stack
14 * -Iterator based approach to have single copy of unwinding core and APIs
15 * needing unwinding, implement the logic in iterator regarding:
16 * = which frame onwards to start capture
17 * = which frame to stop capturing (wchan)
18 * = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)
19 *
20 * vineetg: March 2009
21 * -Implemented correct versions of thread_saved_pc() and get_wchan()
22 *
23 * rajeshwarr: 2008
24 * -Initial implementation
25 */
26
27#include <linux/ptrace.h>
28#include <linux/export.h>
29#include <linux/stacktrace.h>
30#include <linux/kallsyms.h>
31#include <asm/arcregs.h>
32#include <asm/unwind.h>
33#include <asm/switch_to.h>
34
35/*-------------------------------------------------------------------------
36 * Unwinder Iterator
37 *-------------------------------------------------------------------------
38 */
39
40#ifdef CONFIG_ARC_DW2_UNWIND
41
42static void seed_unwind_frame_info(struct task_struct *tsk,
43 struct pt_regs *regs,
44 struct unwind_frame_info *frame_info)
45{
46 if (tsk == NULL && regs == NULL) {
47 unsigned long fp, sp, blink, ret;
48 frame_info->task = current;
49
50 __asm__ __volatile__(
51 "mov %0,r27\n\t"
52 "mov %1,r28\n\t"
53 "mov %2,r31\n\t"
54 "mov %3,r63\n\t"
55 : "=r"(fp), "=r"(sp), "=r"(blink), "=r"(ret)
56 );
57
58 frame_info->regs.r27 = fp;
59 frame_info->regs.r28 = sp;
60 frame_info->regs.r31 = blink;
61 frame_info->regs.r63 = ret;
62 frame_info->call_frame = 0;
63 } else if (regs == NULL) {
64
65 frame_info->task = tsk;
66
67 frame_info->regs.r27 = KSTK_FP(tsk);
68 frame_info->regs.r28 = KSTK_ESP(tsk);
69 frame_info->regs.r31 = KSTK_BLINK(tsk);
70 frame_info->regs.r63 = (unsigned int)__switch_to;
71
72 /* In the prologue of __switch_to, first FP is saved on stack
73 * and then SP is copied to FP. Dwarf assumes cfa as FP based
74 * but we didn't save FP. The value retrieved above is FP's
75 * state in previous frame.
76 * As a work around for this, we unwind from __switch_to start
77 * and adjust SP accordingly. The other limitation is that
78 * __switch_to macro is dwarf rules are not generated for inline
79 * assembly code
80 */
81 frame_info->regs.r27 = 0;
82 frame_info->regs.r28 += 60;
83 frame_info->call_frame = 0;
84
85 } else {
86 frame_info->task = tsk;
87
88 frame_info->regs.r27 = regs->fp;
89 frame_info->regs.r28 = regs->sp;
90 frame_info->regs.r31 = regs->blink;
91 frame_info->regs.r63 = regs->ret;
92 frame_info->call_frame = 0;
93 }
94}
95
96#endif
97
98static noinline unsigned int
99arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
100 int (*consumer_fn) (unsigned int, void *), void *arg)
101{
102#ifdef CONFIG_ARC_DW2_UNWIND
103 int ret = 0;
104 unsigned int address;
105 struct unwind_frame_info frame_info;
106
107 seed_unwind_frame_info(tsk, regs, &frame_info);
108
109 while (1) {
110 address = UNW_PC(&frame_info);
111
112 if (address && __kernel_text_address(address)) {
113 if (consumer_fn(address, arg) == -1)
114 break;
115 }
116
117 ret = arc_unwind(&frame_info);
118
119 if (ret == 0) {
120 frame_info.regs.r63 = frame_info.regs.r31;
121 continue;
122 } else {
123 break;
124 }
125 }
126
127 return address; /* return the last address it saw */
128#else
129 /* On ARC, only Dward based unwinder works. fp based backtracing is
130 * not possible (-fno-omit-frame-pointer) because of the way function
131 * prelogue is setup (callee regs saved and then fp set and not other
132 * way around
133 */
134 pr_warn("CONFIG_ARC_DW2_UNWIND needs to be enabled\n");
135 return 0;
136
137#endif
138}
139
140/*-------------------------------------------------------------------------
141 * callbacks called by unwinder iterator to implement kernel APIs
142 *
143 * The callback can return -1 to force the iterator to stop, which by default
144 * keeps going till the bottom-most frame.
145 *-------------------------------------------------------------------------
146 */
147
148/* Call-back which plugs into unwinding core to dump the stack in
149 * case of panic/OOPs/BUG etc
150 */
151static int __print_sym(unsigned int address, void *unused)
152{
153 __print_symbol(" %s\n", address);
154 return 0;
155}
156
157#ifdef CONFIG_STACKTRACE
158
159/* Call-back which plugs into unwinding core to capture the
160 * traces needed by kernel on /proc/<pid>/stack
161 */
162static int __collect_all(unsigned int address, void *arg)
163{
164 struct stack_trace *trace = arg;
165
166 if (trace->skip > 0)
167 trace->skip--;
168 else
169 trace->entries[trace->nr_entries++] = address;
170
171 if (trace->nr_entries >= trace->max_entries)
172 return -1;
173
174 return 0;
175}
176
177static int __collect_all_but_sched(unsigned int address, void *arg)
178{
179 struct stack_trace *trace = arg;
180
181 if (in_sched_functions(address))
182 return 0;
183
184 if (trace->skip > 0)
185 trace->skip--;
186 else
187 trace->entries[trace->nr_entries++] = address;
188
189 if (trace->nr_entries >= trace->max_entries)
190 return -1;
191
192 return 0;
193}
194
195#endif
196
197static int __get_first_nonsched(unsigned int address, void *unused)
198{
199 if (in_sched_functions(address))
200 return 0;
201
202 return -1;
203}
204
205/*-------------------------------------------------------------------------
206 * APIs expected by various kernel sub-systems
207 *-------------------------------------------------------------------------
208 */
209
210noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs)
211{
212 pr_info("\nStack Trace:\n");
213 arc_unwind_core(tsk, regs, __print_sym, NULL);
214}
215EXPORT_SYMBOL(show_stacktrace);
216
217/* Expected by sched Code */
218void show_stack(struct task_struct *tsk, unsigned long *sp)
219{
220 show_stacktrace(tsk, NULL);
221}
222
223/* Another API expected by schedular, shows up in "ps" as Wait Channel
224 * Ofcourse just returning schedule( ) would be pointless so unwind until
225 * the function is not in schedular code
226 */
227unsigned int get_wchan(struct task_struct *tsk)
228{
229 return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);
230}
231
232#ifdef CONFIG_STACKTRACE
233
234/*
235 * API required by CONFIG_STACKTRACE, CONFIG_LATENCYTOP.
236 * A typical use is when /proc/<pid>/stack is queried by userland
237 */
238void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
239{
240 /* Assumes @tsk is sleeping so unwinds from __switch_to */
241 arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace);
242}
243
244void save_stack_trace(struct stack_trace *trace)
245{
246 /* Pass NULL for task so it unwinds the current call frame */
247 arc_unwind_core(NULL, NULL, __collect_all, trace);
248}
249EXPORT_SYMBOL_GPL(save_stack_trace);
250#endif