arch/x86/kernel/stacktrace.c

   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/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