1 /* 2 * Stack trace management functions 3 * 4 * Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> 5 */ 6 #include <linux/sched.h> 7 #include <linux/stacktrace.h> 8 #include <linux/module.h> 9 #include <linux/uaccess.h> 10 #include <asm/stacktrace.h> 11 12 static int save_stack_stack(void *data, 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 dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace); 83 if (trace->nr_entries < trace->max_entries) 84 trace->entries[trace->nr_entries++] = ULONG_MAX; 85 } 86 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 87 88 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ 89 90 struct stack_frame_user { 91 const void __user *next_fp; 92 unsigned long ret_addr; 93 }; 94 95 static int 96 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) 97 { 98 int ret; 99 100 if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) 101 return 0; 102 103 ret = 1; 104 pagefault_disable(); 105 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) 106 ret = 0; 107 pagefault_enable(); 108 109 return ret; 110 } 111 112 static inline void __save_stack_trace_user(struct stack_trace *trace) 113 { 114 const struct pt_regs *regs = task_pt_regs(current); 115 const void __user *fp = (const void __user *)regs->bp; 116 117 if (trace->nr_entries < trace->max_entries) 118 trace->entries[trace->nr_entries++] = regs->ip; 119 120 while (trace->nr_entries < trace->max_entries) { 121 struct stack_frame_user frame; 122 123 frame.next_fp = NULL; 124 frame.ret_addr = 0; 125 if (!copy_stack_frame(fp, &frame)) 126 break; 127 if ((unsigned long)fp < regs->sp) 128 break; 129 if (frame.ret_addr) { 130 trace->entries[trace->nr_entries++] = 131 frame.ret_addr; 132 } 133 if (fp == frame.next_fp) 134 break; 135 fp = frame.next_fp; 136 } 137 } 138 139 void save_stack_trace_user(struct stack_trace *trace) 140 { 141 /* 142 * Trace user stack if we are not a kernel thread 143 */ 144 if (current->mm) { 145 __save_stack_trace_user(trace); 146 } 147 if (trace->nr_entries < trace->max_entries) 148 trace->entries[trace->nr_entries++] = ULONG_MAX; 149 } 150 151