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         unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
  11
  12         if (unwind_done(state))
  13                 return 0;
  14
  15         return ftrace_graph_ret_addr(state->task, &state->graph_idx,
  16                                      addr, state->sp);
  17 }
  18 EXPORT_SYMBOL_GPL(unwind_get_return_address);
  19
  20 bool unwind_next_frame(struct unwind_state *state)
  21 {
  22         struct stack_info *info = &state->stack_info;
  23
  24         if (unwind_done(state))
  25                 return false;
  26
  27         do {
  28                 unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
  29
  30                 for (state->sp++; state->sp < info->end; state->sp++)
  31                         if (__kernel_text_address(addr))
  32                                 return true;
  33
  34                 state->sp = info->next_sp;
  35
  36         } while (!get_stack_info(state->sp, state->task, info,
  37                                  &state->stack_mask));
  38
  39         return false;
  40 }
  41 EXPORT_SYMBOL_GPL(unwind_next_frame);
  42
  43 void __unwind_start(struct unwind_state *state, struct task_struct *task,
  44                     struct pt_regs *regs, unsigned long *first_frame)
  45 {
  46         memset(state, 0, sizeof(*state));
  47
  48         state->task = task;
  49         state->sp   = first_frame;
  50
  51         get_stack_info(first_frame, state->task, &state->stack_info,
  52                        &state->stack_mask);
  53
  54         /*
  55          * The caller can provide the address of the first frame directly
  56          * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  57          * to start unwinding at.  Skip ahead until we reach it.
  58          */
  59         if (!unwind_done(state) &&
  60             (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  61             !__kernel_text_address(*first_frame)))
  62                 unwind_next_frame(state);
  63 }
  64 EXPORT_SYMBOL_GPL(__unwind_start);