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/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