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;
  11
  12         if (unwind_done(state))
  13                 return 0;
  14
  15         addr = READ_ONCE_NOCHECK(*state->sp);
  16
  17         return ftrace_graph_ret_addr(state->task, &state->graph_idx,
  18                                      addr, state->sp);
  19 }
  20 EXPORT_SYMBOL_GPL(unwind_get_return_address);
  21
  22 bool unwind_next_frame(struct unwind_state *state)
  23 {
  24         struct stack_info *info = &state->stack_info;
  25
  26         if (unwind_done(state))
  27                 return false;
  28
  29         do {
  30                 for (state->sp++; state->sp < info->end; state->sp++) {
  31                         unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
  32
  33                         if (__kernel_text_address(addr))
  34                                 return true;
  35                 }
  36
  37                 state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
  38
  39         } while (!get_stack_info(state->sp, state->task, info,
  40                                  &state->stack_mask));
  41
  42         return false;
  43 }
  44 EXPORT_SYMBOL_GPL(unwind_next_frame);
  45
  46 void __unwind_start(struct unwind_state *state, struct task_struct *task,
  47                     struct pt_regs *regs, unsigned long *first_frame)
  48 {
  49         memset(state, 0, sizeof(*state));
  50
  51         state->task = task;
  52         state->sp   = PTR_ALIGN(first_frame, sizeof(long));
  53
  54         get_stack_info(first_frame, state->task, &state->stack_info,
  55                        &state->stack_mask);
  56
  57         /*
  58          * The caller can provide the address of the first frame directly
  59          * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  60          * to start unwinding at.  Skip ahead until we reach it.
  61          */
  62         if (!unwind_done(state) &&
  63             (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  64             !__kernel_text_address(*first_frame)))
  65                 unwind_next_frame(state);
  66 }
  67 EXPORT_SYMBOL_GPL(__unwind_start);