| | 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 | |
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