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/export.h> 9 #include <linux/uaccess.h> 10 #include <asm/stacktrace.h> 11 #include <asm/unwind.h> 12 13 static int save_stack_address(struct stack_trace *trace, unsigned long addr, 14 bool nosched) 15 { 16 if (nosched && in_sched_functions(addr)) 17 return 0; 18 19 if (trace->skip > 0) { 20 trace->skip--; 21 return 0; 22 } 23 24 if (trace->nr_entries >= trace->max_entries) 25 return -1; 26 27 trace->entries[trace->nr_entries++] = addr; 28 return 0; 29 } 30 31 static void __save_stack_trace(struct stack_trace *trace, 32 struct task_struct *task, struct pt_regs *regs, 33 bool nosched) 34 { 35 struct unwind_state state; 36 unsigned long addr; 37 38 if (regs) 39 save_stack_address(trace, regs->ip, nosched); 40 41 for (unwind_start(&state, task, regs, NULL); !unwind_done(&state); 42 unwind_next_frame(&state)) { 43 addr = unwind_get_return_address(&state); 44 if (!addr || save_stack_address(trace, addr, nosched)) 45 break; 46 } 47 48 if (trace->nr_entries < trace->max_entries) 49 trace->entries[trace->nr_entries++] = ULONG_MAX; 50 } 51 52 /* 53 * Save stack-backtrace addresses into a stack_trace buffer. 54 */ 55 void save_stack_trace(struct stack_trace *trace) 56 { 57 __save_stack_trace(trace, current, NULL, false); 58 } 59 EXPORT_SYMBOL_GPL(save_stack_trace); 60 61 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 62 { 63 __save_stack_trace(trace, current, regs, false); 64 } 65 66 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 67 { 68 if (!try_get_task_stack(tsk)) 69 return; 70 71 __save_stack_trace(trace, tsk, NULL, true); 72 73 put_task_stack(tsk); 74 } 75 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 76 77 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ 78 79 struct stack_frame_user { 80 const void __user *next_fp; 81 unsigned long ret_addr; 82 }; 83 84 static int 85 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) 86 { 87 int ret; 88 89 if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) 90 return 0; 91 92 ret = 1; 93 pagefault_disable(); 94 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) 95 ret = 0; 96 pagefault_enable(); 97 98 return ret; 99 } 100 101 static inline void __save_stack_trace_user(struct stack_trace *trace) 102 { 103 const struct pt_regs *regs = task_pt_regs(current); 104 const void __user *fp = (const void __user *)regs->bp; 105 106 if (trace->nr_entries < trace->max_entries) 107 trace->entries[trace->nr_entries++] = regs->ip; 108 109 while (trace->nr_entries < trace->max_entries) { 110 struct stack_frame_user frame; 111 112 frame.next_fp = NULL; 113 frame.ret_addr = 0; 114 if (!copy_stack_frame(fp, &frame)) 115 break; 116 if ((unsigned long)fp < regs->sp) 117 break; 118 if (frame.ret_addr) { 119 trace->entries[trace->nr_entries++] = 120 frame.ret_addr; 121 } 122 if (fp == frame.next_fp) 123 break; 124 fp = frame.next_fp; 125 } 126 } 127 128 void save_stack_trace_user(struct stack_trace *trace) 129 { 130 /* 131 * Trace user stack if we are not a kernel thread 132 */ 133 if (current->mm) { 134 __save_stack_trace_user(trace); 135 } 136 if (trace->nr_entries < trace->max_entries) 137 trace->entries[trace->nr_entries++] = ULONG_MAX; 138 } 139 140