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/sched/debug.h> 8 #include <linux/stacktrace.h> 9 #include <linux/export.h> 10 #include <linux/uaccess.h> 11 #include <asm/stacktrace.h> 12 #include <asm/unwind.h> 13 14 static int save_stack_address(struct stack_trace *trace, unsigned long addr, 15 bool nosched) 16 { 17 if (nosched && in_sched_functions(addr)) 18 return 0; 19 20 if (trace->skip > 0) { 21 trace->skip--; 22 return 0; 23 } 24 25 if (trace->nr_entries >= trace->max_entries) 26 return -1; 27 28 trace->entries[trace->nr_entries++] = addr; 29 return 0; 30 } 31 32 static void __save_stack_trace(struct stack_trace *trace, 33 struct task_struct *task, struct pt_regs *regs, 34 bool nosched) 35 { 36 struct unwind_state state; 37 unsigned long addr; 38 39 if (regs) 40 save_stack_address(trace, regs->ip, nosched); 41 42 for (unwind_start(&state, task, regs, NULL); !unwind_done(&state); 43 unwind_next_frame(&state)) { 44 addr = unwind_get_return_address(&state); 45 if (!addr || save_stack_address(trace, addr, nosched)) 46 break; 47 } 48 49 if (trace->nr_entries < trace->max_entries) 50 trace->entries[trace->nr_entries++] = ULONG_MAX; 51 } 52 53 /* 54 * Save stack-backtrace addresses into a stack_trace buffer. 55 */ 56 void save_stack_trace(struct stack_trace *trace) 57 { 58 __save_stack_trace(trace, current, NULL, false); 59 } 60 EXPORT_SYMBOL_GPL(save_stack_trace); 61 62 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 63 { 64 __save_stack_trace(trace, current, regs, false); 65 } 66 67 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 68 { 69 if (!try_get_task_stack(tsk)) 70 return; 71 72 __save_stack_trace(trace, tsk, NULL, true); 73 74 put_task_stack(tsk); 75 } 76 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 77 78 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ 79 80 struct stack_frame_user { 81 const void __user *next_fp; 82 unsigned long ret_addr; 83 }; 84 85 static int 86 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) 87 { 88 int ret; 89 90 if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) 91 return 0; 92 93 ret = 1; 94 pagefault_disable(); 95 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) 96 ret = 0; 97 pagefault_enable(); 98 99 return ret; 100 } 101 102 static inline void __save_stack_trace_user(struct stack_trace *trace) 103 { 104 const struct pt_regs *regs = task_pt_regs(current); 105 const void __user *fp = (const void __user *)regs->bp; 106 107 if (trace->nr_entries < trace->max_entries) 108 trace->entries[trace->nr_entries++] = regs->ip; 109 110 while (trace->nr_entries < trace->max_entries) { 111 struct stack_frame_user frame; 112 113 frame.next_fp = NULL; 114 frame.ret_addr = 0; 115 if (!copy_stack_frame(fp, &frame)) 116 break; 117 if ((unsigned long)fp < regs->sp) 118 break; 119 if (frame.ret_addr) { 120 trace->entries[trace->nr_entries++] = 121 frame.ret_addr; 122 } 123 if (fp == frame.next_fp) 124 break; 125 fp = frame.next_fp; 126 } 127 } 128 129 void save_stack_trace_user(struct stack_trace *trace) 130 { 131 /* 132 * Trace user stack if we are not a kernel thread 133 */ 134 if (current->mm) { 135 __save_stack_trace_user(trace); 136 } 137 if (trace->nr_entries < trace->max_entries) 138 trace->entries[trace->nr_entries++] = ULONG_MAX; 139 } 140 141