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/sched/debug.h> 8 #include <linux/sched/task_stack.h> 9 #include <linux/stacktrace.h> 10 #include <linux/export.h> 11 #include <linux/uaccess.h> 12 #include <asm/stacktrace.h> 13 #include <asm/unwind.h> 14 15 static int save_stack_address(struct stack_trace *trace, unsigned long addr, 16 bool nosched) 17 { 18 if (nosched && in_sched_functions(addr)) 19 return 0; 20 21 if (trace->skip > 0) { 22 trace->skip--; 23 return 0; 24 } 25 26 if (trace->nr_entries >= trace->max_entries) 27 return -1; 28 29 trace->entries[trace->nr_entries++] = addr; 30 return 0; 31 } 32 33 static void __save_stack_trace(struct stack_trace *trace, 34 struct task_struct *task, struct pt_regs *regs, 35 bool nosched) 36 { 37 struct unwind_state state; 38 unsigned long addr; 39 40 if (regs) 41 save_stack_address(trace, regs->ip, nosched); 42 43 for (unwind_start(&state, task, regs, NULL); !unwind_done(&state); 44 unwind_next_frame(&state)) { 45 addr = unwind_get_return_address(&state); 46 if (!addr || save_stack_address(trace, addr, nosched)) 47 break; 48 } 49 50 if (trace->nr_entries < trace->max_entries) 51 trace->entries[trace->nr_entries++] = ULONG_MAX; 52 } 53 54 /* 55 * Save stack-backtrace addresses into a stack_trace buffer. 56 */ 57 void save_stack_trace(struct stack_trace *trace) 58 { 59 __save_stack_trace(trace, current, NULL, false); 60 } 61 EXPORT_SYMBOL_GPL(save_stack_trace); 62 63 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 64 { 65 __save_stack_trace(trace, current, regs, false); 66 } 67 68 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 69 { 70 if (!try_get_task_stack(tsk)) 71 return; 72 73 __save_stack_trace(trace, tsk, NULL, true); 74 75 put_task_stack(tsk); 76 } 77 EXPORT_SYMBOL_GPL(save_stack_trace_tsk); 78 79 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ 80 81 struct stack_frame_user { 82 const void __user *next_fp; 83 unsigned long ret_addr; 84 }; 85 86 static int 87 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) 88 { 89 int ret; 90 91 if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) 92 return 0; 93 94 ret = 1; 95 pagefault_disable(); 96 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) 97 ret = 0; 98 pagefault_enable(); 99 100 return ret; 101 } 102 103 static inline void __save_stack_trace_user(struct stack_trace *trace) 104 { 105 const struct pt_regs *regs = task_pt_regs(current); 106 const void __user *fp = (const void __user *)regs->bp; 107 108 if (trace->nr_entries < trace->max_entries) 109 trace->entries[trace->nr_entries++] = regs->ip; 110 111 while (trace->nr_entries < trace->max_entries) { 112 struct stack_frame_user frame; 113 114 frame.next_fp = NULL; 115 frame.ret_addr = 0; 116 if (!copy_stack_frame(fp, &frame)) 117 break; 118 if ((unsigned long)fp < regs->sp) 119 break; 120 if (frame.ret_addr) { 121 trace->entries[trace->nr_entries++] = 122 frame.ret_addr; 123 } 124 if (fp == frame.next_fp) 125 break; 126 fp = frame.next_fp; 127 } 128 } 129 130 void save_stack_trace_user(struct stack_trace *trace) 131 { 132 /* 133 * Trace user stack if we are not a kernel thread 134 */ 135 if (current->mm) { 136 __save_stack_trace_user(trace); 137 } 138 if (trace->nr_entries < trace->max_entries) 139 trace->entries[trace->nr_entries++] = ULONG_MAX; 140 } 141 142