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/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