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 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
  16                      struct task_struct *task, struct pt_regs *regs)
  17 {
  18         struct unwind_state state;
  19         unsigned long addr;
  20
  21         if (regs && !consume_entry(cookie, regs->ip))
  22                 return;
  23
  24         for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
  25              unwind_next_frame(&state)) {
  26                 addr = unwind_get_return_address(&state);
  27                 if (!addr || !consume_entry(cookie, addr))
  28                         break;
  29         }
  30 }
  31
  32 int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
  33                              void *cookie, struct task_struct *task)
  34 {
  35         struct unwind_state state;
  36         struct pt_regs *regs;
  37         unsigned long addr;
  38
  39         for (unwind_start(&state, task, NULL, NULL);
  40              !unwind_done(&state) && !unwind_error(&state);
  41              unwind_next_frame(&state)) {
  42
  43                 regs = unwind_get_entry_regs(&state, NULL);
  44                 if (regs) {
  45                         /* Success path for user tasks */
  46                         if (user_mode(regs))
  47                                 return 0;
  48
  49                         /*
  50                          * Kernel mode registers on the stack indicate an
  51                          * in-kernel interrupt or exception (e.g., preemption
  52                          * or a page fault), which can make frame pointers
  53                          * unreliable.
  54                          */
  55                         if (IS_ENABLED(CONFIG_FRAME_POINTER))
  56                                 return -EINVAL;
  57                 }
  58
  59                 addr = unwind_get_return_address(&state);
  60
  61                 /*
  62                  * A NULL or invalid return address probably means there's some
  63                  * generated code which __kernel_text_address() doesn't know
  64                  * about.
  65                  */
  66                 if (!addr)
  67                         return -EINVAL;
  68
  69                 if (!consume_entry(cookie, addr))
  70                         return -EINVAL;
  71         }
  72
  73         /* Check for stack corruption */
  74         if (unwind_error(&state))
  75                 return -EINVAL;
  76
  77         return 0;
  78 }
  79
  80 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  81
  82 struct stack_frame_user {
  83         const void __user       *next_fp;
  84         unsigned long           ret_addr;
  85 };
  86
  87 static int
  88 copy_stack_frame(const struct stack_frame_user __user *fp,
  89                  struct stack_frame_user *frame)
  90 {
  91         int ret;
  92
  93         if (!__access_ok(fp, sizeof(*frame)))
  94                 return 0;
  95
  96         ret = 1;
  97         pagefault_disable();
  98         if (__get_user(frame->next_fp, &fp->next_fp) ||
  99             __get_user(frame->ret_addr, &fp->ret_addr))
 100                 ret = 0;
 101         pagefault_enable();
 102
 103         return ret;
 104 }
 105
 106 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
 107                           const struct pt_regs *regs)
 108 {
 109         const void __user *fp = (const void __user *)regs->bp;
 110
 111         if (!consume_entry(cookie, regs->ip))
 112                 return;
 113
 114         while (1) {
 115                 struct stack_frame_user frame;
 116
 117                 frame.next_fp = NULL;
 118                 frame.ret_addr = 0;
 119                 if (!copy_stack_frame(fp, &frame))
 120                         break;
 121                 if ((unsigned long)fp < regs->sp)
 122                         break;
 123                 if (!frame.ret_addr)
 124                         break;
 125                 if (!consume_entry(cookie, frame.ret_addr))
 126                         break;
 127                 fp = frame.next_fp;
 128         }
 129 }
 130