1 /* 2 * Stack trace management functions 3 * 4 * Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <[email protected]> 5 */ 6 #include <linux/sched.h> 7 #include <linux/stacktrace.h> 8 #include <linux/export.h> 9 #include <linux/uaccess.h> 10 #include <asm/stacktrace.h> 11 12 static int save_stack_stack(void *data, const char *name) 13 { 14 return 0; 15 } 16 17 static int 18 __save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched) 19 { 20 struct stack_trace *trace = data; 21 #ifdef CONFIG_FRAME_POINTER 22 if (!reliable) 23 return 0; 24 #endif 25 if (nosched && in_sched_functions(addr)) 26 return 0; 27 if (trace->skip > 0) { 28 trace->skip--; 29 return 0; 30 } 31 if (trace->nr_entries < trace->max_entries) { 32 trace->entries[trace->nr_entries++] = addr; 33 return 0; 34 } else { 35 return -1; /* no more room, stop walking the stack */ 36 } 37 } 38 39 static int save_stack_address(void *data, unsigned long addr, int reliable) 40 { 41 return __save_stack_address(data, addr, reliable, false); 42 } 43 44 static int 45 save_stack_address_nosched(void *data, unsigned long addr, int reliable) 46 { 47 return __save_stack_address(data, addr, reliable, true); 48 } 49 50 static const struct stacktrace_ops save_stack_ops = { 51 .stack = save_stack_stack, 52 .address = save_stack_address, 53 .walk_stack = print_context_stack, 54 }; 55 56 static const struct stacktrace_ops save_stack_ops_nosched = { 57 .stack = save_stack_stack, 58 .address = save_stack_address_nosched, 59 .walk_stack = print_context_stack, 60 }; 61 62 /* 63 * Save stack-backtrace addresses into a stack_trace buffer. 64 */ 65 void save_stack_trace(struct stack_trace *trace) 66 { 67 dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace); 68 if (trace->nr_entries < trace->max_entries) 69 trace->entries[trace->nr_entries++] = ULONG_MAX; 70 } 71 EXPORT_SYMBOL_GPL(save_stack_trace); 72 73 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 74 { 75 dump_trace(current, regs, NULL, 0, &save_stack_ops, trace); 76 if (trace->nr_entries < trace->max_entries) 77 trace->entries[trace->nr_entries++] = ULONG_MAX; 78 } 79 80 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 81 { 82 if (!try_get_task_stack(tsk)) 83 return; 84 85 dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace); 86 if (trace->nr_entries < trace->max_entries) 87 trace->entries[trace->nr_entries++] = ULONG_MAX; 88 89 put_task_stack(tsk); 90 } 91 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 92 93 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ 94 95 struct stack_frame_user { 96 const void __user *next_fp; 97 unsigned long ret_addr; 98 }; 99 100 static int 101 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) 102 { 103 int ret; 104 105 if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) 106 return 0; 107 108 ret = 1; 109 pagefault_disable(); 110 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) 111 ret = 0; 112 pagefault_enable(); 113 114 return ret; 115 } 116 117 static inline void __save_stack_trace_user(struct stack_trace *trace) 118 { 119 const struct pt_regs *regs = task_pt_regs(current); 120 const void __user *fp = (const void __user *)regs->bp; 121 122 if (trace->nr_entries < trace->max_entries) 123 trace->entries[trace->nr_entries++] = regs->ip; 124 125 while (trace->nr_entries < trace->max_entries) { 126 struct stack_frame_user frame; 127 128 frame.next_fp = NULL; 129 frame.ret_addr = 0; 130 if (!copy_stack_frame(fp, &frame)) 131 break; 132 if ((unsigned long)fp < regs->sp) 133 break; 134 if (frame.ret_addr) { 135 trace->entries[trace->nr_entries++] = 136 frame.ret_addr; 137 } 138 if (fp == frame.next_fp) 139 break; 140 fp = frame.next_fp; 141 } 142 } 143 144 void save_stack_trace_user(struct stack_trace *trace) 145 { 146 /* 147 * Trace user stack if we are not a kernel thread 148 */ 149 if (current->mm) { 150 __save_stack_trace_user(trace); 151 } 152 if (trace->nr_entries < trace->max_entries) 153 trace->entries[trace->nr_entries++] = ULONG_MAX; 154 } 155 156