1#include <linux/export.h>
2#include <linux/sched.h>
3#include <linux/stacktrace.h>
4
5#include <asm/stacktrace.h>
6
7#if defined(CONFIG_FRAME_POINTER)
8
9#ifdef CONFIG_KALLSYMS
10#include <linux/kallsyms.h>
11#include <linux/module.h>
12
13static unsigned long tbi_boing_addr;
14static unsigned long tbi_boing_size;
15
16static void tbi_boing_init(void)
17{
18	/* We need to know where TBIBoingVec is and it's size */
19	unsigned long size;
20	unsigned long offset;
21	char modname[MODULE_NAME_LEN];
22	char name[KSYM_NAME_LEN];
23	tbi_boing_addr = kallsyms_lookup_name("___TBIBoingVec");
24	if (!tbi_boing_addr)
25		tbi_boing_addr = 1;
26	else if (!lookup_symbol_attrs(tbi_boing_addr, &size,
27				      &offset, modname, name))
28		tbi_boing_size = size;
29}
30#endif
31
32#define ALIGN_DOWN(addr, size)  ((addr)&(~((size)-1)))
33
34/*
35 * Unwind the current stack frame and store the new register values in the
36 * structure passed as argument. Unwinding is equivalent to a function return,
37 * hence the new PC value rather than LR should be used for backtrace.
38 */
39int notrace unwind_frame(struct stackframe *frame)
40{
41	struct metag_frame *fp = (struct metag_frame *)frame->fp;
42	unsigned long lr;
43	unsigned long fpnew;
44
45	if (frame->fp & 0x7)
46		return -EINVAL;
47
48	fpnew = fp->fp;
49	lr = fp->lr - 4;
50
51#ifdef CONFIG_KALLSYMS
52	/* If we've reached TBIBoingVec then we're at an interrupt
53	 * entry point or a syscall entry point. The frame pointer
54	 * points to a pt_regs which can be used to continue tracing on
55	 * the other side of the boing.
56	 */
57	if (!tbi_boing_addr)
58		tbi_boing_init();
59	if (tbi_boing_size && lr >= tbi_boing_addr &&
60	    lr < tbi_boing_addr + tbi_boing_size) {
61		struct pt_regs *regs = (struct pt_regs *)fpnew;
62		if (user_mode(regs))
63			return -EINVAL;
64		fpnew = regs->ctx.AX[1].U0;
65		lr = regs->ctx.DX[4].U1;
66	}
67#endif
68
69	/* stack grows up, so frame pointers must decrease */
70	if (fpnew < (ALIGN_DOWN((unsigned long)fp, THREAD_SIZE) +
71		     sizeof(struct thread_info)) || fpnew >= (unsigned long)fp)
72		return -EINVAL;
73
74	/* restore the registers from the stack frame */
75	frame->fp = fpnew;
76	frame->pc = lr;
77
78	return 0;
79}
80#else
81int notrace unwind_frame(struct stackframe *frame)
82{
83	struct metag_frame *sp = (struct metag_frame *)frame->sp;
84
85	if (frame->sp & 0x7)
86		return -EINVAL;
87
88	while (!kstack_end(sp)) {
89		unsigned long addr = sp->lr - 4;
90		sp--;
91
92		if (__kernel_text_address(addr)) {
93			frame->sp = (unsigned long)sp;
94			frame->pc = addr;
95			return 0;
96		}
97	}
98	return -EINVAL;
99}
100#endif
101
102void notrace walk_stackframe(struct stackframe *frame,
103		     int (*fn)(struct stackframe *, void *), void *data)
104{
105	while (1) {
106		int ret;
107
108		if (fn(frame, data))
109			break;
110		ret = unwind_frame(frame);
111		if (ret < 0)
112			break;
113	}
114}
115EXPORT_SYMBOL(walk_stackframe);
116
117#ifdef CONFIG_STACKTRACE
118struct stack_trace_data {
119	struct stack_trace *trace;
120	unsigned int no_sched_functions;
121	unsigned int skip;
122};
123
124static int save_trace(struct stackframe *frame, void *d)
125{
126	struct stack_trace_data *data = d;
127	struct stack_trace *trace = data->trace;
128	unsigned long addr = frame->pc;
129
130	if (data->no_sched_functions && in_sched_functions(addr))
131		return 0;
132	if (data->skip) {
133		data->skip--;
134		return 0;
135	}
136
137	trace->entries[trace->nr_entries++] = addr;
138
139	return trace->nr_entries >= trace->max_entries;
140}
141
142void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
143{
144	struct stack_trace_data data;
145	struct stackframe frame;
146
147	data.trace = trace;
148	data.skip = trace->skip;
149
150	if (tsk != current) {
151#ifdef CONFIG_SMP
152		/*
153		 * What guarantees do we have here that 'tsk' is not
154		 * running on another CPU?  For now, ignore it as we
155		 * can't guarantee we won't explode.
156		 */
157		if (trace->nr_entries < trace->max_entries)
158			trace->entries[trace->nr_entries++] = ULONG_MAX;
159		return;
160#else
161		data.no_sched_functions = 1;
162		frame.fp = thread_saved_fp(tsk);
163		frame.sp = thread_saved_sp(tsk);
164		frame.lr = 0;		/* recovered from the stack */
165		frame.pc = thread_saved_pc(tsk);
166#endif
167	} else {
168		register unsigned long current_sp asm ("A0StP");
169
170		data.no_sched_functions = 0;
171		frame.fp = (unsigned long)__builtin_frame_address(0);
172		frame.sp = current_sp;
173		frame.lr = (unsigned long)__builtin_return_address(0);
174		frame.pc = (unsigned long)save_stack_trace_tsk;
175	}
176
177	walk_stackframe(&frame, save_trace, &data);
178	if (trace->nr_entries < trace->max_entries)
179		trace->entries[trace->nr_entries++] = ULONG_MAX;
180}
181
182void save_stack_trace(struct stack_trace *trace)
183{
184	save_stack_trace_tsk(current, trace);
185}
186EXPORT_SYMBOL_GPL(save_stack_trace);
187#endif
188