arch/x86/kernel/unwind_guess.c

   1 #include <linux/sched.h>
   2 #include <linux/ftrace.h>
   3 #include <asm/ptrace.h>
   4 #include <asm/bitops.h>
   5 #include <asm/stacktrace.h>
   6 #include <asm/unwind.h>
   7
   8 unsigned long unwind_get_return_address(struct unwind_state *state)
   9 {
  10         if (unwind_done(state))
  11                 return 0;
  12
  13         return ftrace_graph_ret_addr(state->task, &state->graph_idx,
  14                                      *state->sp, state->sp);
  15 }
  16 EXPORT_SYMBOL_GPL(unwind_get_return_address);
  17
  18 bool unwind_next_frame(struct unwind_state *state)
  19 {
  20         struct stack_info *info = &state->stack_info;
  21
  22         if (unwind_done(state))
  23                 return false;
  24
  25         do {
  26                 for (state->sp++; state->sp < info->end; state->sp++)
  27                         if (__kernel_text_address(*state->sp))
  28                                 return true;
  29
  30                 state->sp = info->next_sp;
  31
  32         } while (!get_stack_info(state->sp, state->task, info,
  33                                  &state->stack_mask));
  34
  35         return false;
  36 }
  37 EXPORT_SYMBOL_GPL(unwind_next_frame);
  38
  39 void __unwind_start(struct unwind_state *state, struct task_struct *task,
  40                     struct pt_regs *regs, unsigned long *first_frame)
  41 {
  42         memset(state, 0, sizeof(*state));
  43
  44         state->task = task;
  45         state->sp   = first_frame;
  46
  47         get_stack_info(first_frame, state->task, &state->stack_info,
  48                        &state->stack_mask);
  49
  50         /*
  51          * The caller can provide the address of the first frame directly
  52          * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  53          * to start unwinding at.  Skip ahead until we reach it.
  54          */
  55         if (!unwind_done(state) &&
  56             (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  57             !__kernel_text_address(*first_frame)))
  58                 unwind_next_frame(state);
  59 }
  60 EXPORT_SYMBOL_GPL(__unwind_start);