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