1#include <linux/module.h> 2#include <linux/sched.h> 3#include <linux/stacktrace.h> 4 5#include <asm/stacktrace.h> 6 7#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) 8/* 9 * Unwind the current stack frame and store the new register values in the 10 * structure passed as argument. Unwinding is equivalent to a function return, 11 * hence the new PC value rather than LR should be used for backtrace. 12 * 13 * With framepointer enabled, a simple function prologue looks like this: 14 * mov ip, sp 15 * stmdb sp!, {fp, ip, lr, pc} 16 * sub fp, ip, #4 17 * 18 * A simple function epilogue looks like this: 19 * ldm sp, {fp, sp, pc} 20 * 21 * Note that with framepointer enabled, even the leaf functions have the same 22 * prologue and epilogue, therefore we can ignore the LR value in this case. 23 */ 24int notrace unwind_frame(struct stackframe *frame) 25{ 26 unsigned long high, low; 27 unsigned long fp = frame->fp; 28 29 /* only go to a higher address on the stack */ 30 low = frame->sp; 31 high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE; 32 33 /* check current frame pointer is within bounds */ 34 if (fp < (low + 12) || fp + 4 >= high) 35 return -EINVAL; 36 37 /* restore the registers from the stack frame */ 38 frame->fp = *(unsigned long *)(fp - 12); 39 frame->sp = *(unsigned long *)(fp - 8); 40 frame->pc = *(unsigned long *)(fp - 4); 41 42 return 0; 43} 44#endif 45 46void notrace walk_stackframe(struct stackframe *frame, 47 int (*fn)(struct stackframe *, void *), void *data) 48{ 49 while (1) { 50 int ret; 51 52 if (fn(frame, data)) 53 break; 54 ret = unwind_frame(frame); 55 if (ret < 0) 56 break; 57 } 58} 59EXPORT_SYMBOL(walk_stackframe); 60 61#ifdef CONFIG_STACKTRACE 62struct stack_trace_data { 63 struct stack_trace *trace; 64 unsigned int no_sched_functions; 65 unsigned int skip; 66}; 67 68static int save_trace(struct stackframe *frame, void *d) 69{ 70 struct stack_trace_data *data = d; 71 struct stack_trace *trace = data->trace; 72 unsigned long addr = frame->pc; 73 74 if (data->no_sched_functions && in_sched_functions(addr)) 75 return 0; 76 if (data->skip) { 77 data->skip--; 78 return 0; 79 } 80 81 trace->entries[trace->nr_entries++] = addr; 82 83 return trace->nr_entries >= trace->max_entries; 84} 85 86void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 87{ 88 struct stack_trace_data data; 89 struct stackframe frame; 90 91 data.trace = trace; 92 data.skip = trace->skip; 93 94 if (tsk != current) { 95#ifdef CONFIG_SMP 96 /* 97 * What guarantees do we have here that 'tsk' 98 * is not running on another CPU? 99 */ 100 BUG(); 101#else 102 data.no_sched_functions = 1; 103 frame.fp = thread_saved_fp(tsk); 104 frame.sp = thread_saved_sp(tsk); 105 frame.lr = 0; /* recovered from the stack */ 106 frame.pc = thread_saved_pc(tsk); 107#endif 108 } else { 109 register unsigned long current_sp asm ("sp"); 110 111 data.no_sched_functions = 0; 112 frame.fp = (unsigned long)__builtin_frame_address(0); 113 frame.sp = current_sp; 114 frame.lr = (unsigned long)__builtin_return_address(0); 115 frame.pc = (unsigned long)save_stack_trace_tsk; 116 } 117 118 walk_stackframe(&frame, save_trace, &data); 119 if (trace->nr_entries < trace->max_entries) 120 trace->entries[trace->nr_entries++] = ULONG_MAX; 121} 122 123void save_stack_trace(struct stack_trace *trace) 124{ 125 save_stack_trace_tsk(current, trace); 126} 127EXPORT_SYMBOL_GPL(save_stack_trace); 128#endif 129