arch/x86/kernel/stacktrace.c

   1 /*
   2  * Stack trace management functions
   3  *
   4  *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <[email protected]>
   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 int save_stack_stack(void *data, char *name)
  13 {
  14         return 0;
  15 }
  16
  17 static void
  18 __save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
  19 {
  20         struct stack_trace *trace = data;
  21 #ifdef CONFIG_FRAME_POINTER
  22         if (!reliable)
  23                 return;
  24 #endif
  25         if (nosched && in_sched_functions(addr))
  26                 return;
  27         if (trace->skip > 0) {
  28                 trace->skip--;
  29                 return;
  30         }
  31         if (trace->nr_entries < trace->max_entries)
  32                 trace->entries[trace->nr_entries++] = addr;
  33 }
  34
  35 static void save_stack_address(void *data, unsigned long addr, int reliable)
  36 {
  37         return __save_stack_address(data, addr, reliable, false);
  38 }
  39
  40 static void
  41 save_stack_address_nosched(void *data, unsigned long addr, int reliable)
  42 {
  43         return __save_stack_address(data, addr, reliable, true);
  44 }
  45
  46 static const struct stacktrace_ops save_stack_ops = {
  47         .stack          = save_stack_stack,
  48         .address        = save_stack_address,
  49         .walk_stack     = print_context_stack,
  50 };
  51
  52 static const struct stacktrace_ops save_stack_ops_nosched = {
  53         .stack          = save_stack_stack,
  54         .address        = save_stack_address_nosched,
  55         .walk_stack     = print_context_stack,
  56 };
  57
  58 /*
  59  * Save stack-backtrace addresses into a stack_trace buffer.
  60  */
  61 void save_stack_trace(struct stack_trace *trace)
  62 {
  63         dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
  64         if (trace->nr_entries < trace->max_entries)
  65                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  66 }
  67 EXPORT_SYMBOL_GPL(save_stack_trace);
  68
  69 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
  70 {
  71         dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
  72         if (trace->nr_entries < trace->max_entries)
  73                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  74 }
  75
  76 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  77 {
  78         dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
  79         if (trace->nr_entries < trace->max_entries)
  80                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  81 }
  82 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
  83
  84 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  85
  86 struct stack_frame_user {
  87         const void __user       *next_fp;
  88         unsigned long           ret_addr;
  89 };
  90
  91 static int
  92 copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
  93 {
  94         int ret;
  95
  96         if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
  97                 return 0;
  98
  99         ret = 1;
 100         pagefault_disable();
 101         if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
 102                 ret = 0;
 103         pagefault_enable();
 104
 105         return ret;
 106 }
 107
 108 static inline void __save_stack_trace_user(struct stack_trace *trace)
 109 {
 110         const struct pt_regs *regs = task_pt_regs(current);
 111         const void __user *fp = (const void __user *)regs->bp;
 112
 113         if (trace->nr_entries < trace->max_entries)
 114                 trace->entries[trace->nr_entries++] = regs->ip;
 115
 116         while (trace->nr_entries < trace->max_entries) {
 117                 struct stack_frame_user frame;
 118
 119                 frame.next_fp = NULL;
 120                 frame.ret_addr = 0;
 121                 if (!copy_stack_frame(fp, &frame))
 122                         break;
 123                 if ((unsigned long)fp < regs->sp)
 124                         break;
 125                 if (frame.ret_addr) {
 126                         trace->entries[trace->nr_entries++] =
 127                                 frame.ret_addr;
 128                 }
 129                 if (fp == frame.next_fp)
 130                         break;
 131                 fp = frame.next_fp;
 132         }
 133 }
 134
 135 void save_stack_trace_user(struct stack_trace *trace)
 136 {
 137         /*
 138          * Trace user stack if we are not a kernel thread
 139          */
 140         if (current->mm) {
 141                 __save_stack_trace_user(trace);
 142         }
 143         if (trace->nr_entries < trace->max_entries)
 144                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 145 }
 146