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/module.h>
   9 #include <linux/uaccess.h>
  10 #include <asm/stacktrace.h>
  11
  12 static void save_stack_warning(void *data, char *msg)
  13 {
  14 }
  15
  16 static void
  17 save_stack_warning_symbol(void *data, char *msg, unsigned long symbol)
  18 {
  19 }
  20
  21 static int save_stack_stack(void *data, char *name)
  22 {
  23         return 0;
  24 }
  25
  26 static void
  27 __save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
  28 {
  29         struct stack_trace *trace = data;
  30 #ifdef CONFIG_FRAME_POINTER
  31         if (!reliable)
  32                 return;
  33 #endif
  34         if (nosched && in_sched_functions(addr))
  35                 return;
  36         if (trace->skip > 0) {
  37                 trace->skip--;
  38                 return;
  39         }
  40         if (trace->nr_entries < trace->max_entries)
  41                 trace->entries[trace->nr_entries++] = addr;
  42 }
  43
  44 static void save_stack_address(void *data, unsigned long addr, int reliable)
  45 {
  46         return __save_stack_address(data, addr, reliable, false);
  47 }
  48
  49 static void
  50 save_stack_address_nosched(void *data, unsigned long addr, int reliable)
  51 {
  52         return __save_stack_address(data, addr, reliable, true);
  53 }
  54
  55 static const struct stacktrace_ops save_stack_ops = {
  56         .warning        = save_stack_warning,
  57         .warning_symbol = save_stack_warning_symbol,
  58         .stack          = save_stack_stack,
  59         .address        = save_stack_address,
  60         .walk_stack     = print_context_stack,
  61 };
  62
  63 static const struct stacktrace_ops save_stack_ops_nosched = {
  64         .warning        = save_stack_warning,
  65         .warning_symbol = save_stack_warning_symbol,
  66         .stack          = save_stack_stack,
  67         .address        = save_stack_address_nosched,
  68         .walk_stack     = print_context_stack,
  69 };
  70
  71 /*
  72  * Save stack-backtrace addresses into a stack_trace buffer.
  73  */
  74 void save_stack_trace(struct stack_trace *trace)
  75 {
  76         dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
  77         if (trace->nr_entries < trace->max_entries)
  78                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  79 }
  80 EXPORT_SYMBOL_GPL(save_stack_trace);
  81
  82 void save_stack_trace_bp(struct stack_trace *trace, unsigned long bp)
  83 {
  84         dump_trace(current, NULL, NULL, bp, &save_stack_ops, trace);
  85         if (trace->nr_entries < trace->max_entries)
  86                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  87 }
  88
  89 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  90 {
  91         dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
  92         if (trace->nr_entries < trace->max_entries)
  93                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  94 }
  95 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
  96
  97 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  98
  99 struct stack_frame_user {
 100         const void __user       *next_fp;
 101         unsigned long           ret_addr;
 102 };
 103
 104 static int
 105 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
 106 {
 107         int ret;
 108
 109         if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
 110                 return 0;
 111
 112         ret = 1;
 113         pagefault_disable();
 114         if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
 115                 ret = 0;
 116         pagefault_enable();
 117
 118         return ret;
 119 }
 120
 121 static inline void __save_stack_trace_user(struct stack_trace *trace)
 122 {
 123         const struct pt_regs *regs = task_pt_regs(current);
 124         const void __user *fp = (const void __user *)regs->bp;
 125
 126         if (trace->nr_entries < trace->max_entries)
 127                 trace->entries[trace->nr_entries++] = regs->ip;
 128
 129         while (trace->nr_entries < trace->max_entries) {
 130                 struct stack_frame_user frame;
 131
 132                 frame.next_fp = NULL;
 133                 frame.ret_addr = 0;
 134                 if (!copy_stack_frame(fp, &frame))
 135                         break;
 136                 if ((unsigned long)fp < regs->sp)
 137                         break;
 138                 if (frame.ret_addr) {
 139                         trace->entries[trace->nr_entries++] =
 140                                 frame.ret_addr;
 141                 }
 142                 if (fp == frame.next_fp)
 143                         break;
 144                 fp = frame.next_fp;
 145         }
 146 }
 147
 148 void save_stack_trace_user(struct stack_trace *trace)
 149 {
 150         /*
 151          * Trace user stack if we are not a kernel thread
 152          */
 153         if (current->mm) {
 154                 __save_stack_trace_user(trace);
 155         }
 156         if (trace->nr_entries < trace->max_entries)
 157                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 158 }
 159