arch/x86/kernel/unwind_guess.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/sched.h>
   3 #include <linux/ftrace.h>
   4 #include <asm/ptrace.h>
   5 #include <asm/bitops.h>
   6 #include <asm/stacktrace.h>
   7 #include <asm/unwind.h>
   8
   9 unsigned long unwind_get_return_address(struct unwind_state *state)
  10 {
  11         unsigned long addr;
  12
  13         if (unwind_done(state))
  14                 return 0;
  15
  16         addr = READ_ONCE_NOCHECK(*state->sp);
  17
  18         return unwind_recover_ret_addr(state, addr, state->sp);
  19 }
  20 EXPORT_SYMBOL_GPL(unwind_get_return_address);
  21
  22 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
  23 {
  24         return NULL;
  25 }
  26
  27 bool unwind_next_frame(struct unwind_state *state)
  28 {
  29         struct stack_info *info = &state->stack_info;
  30
  31         if (unwind_done(state))
  32                 return false;
  33
  34         do {
  35                 for (state->sp++; state->sp < info->end; state->sp++) {
  36                         unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
  37
  38                         if (__kernel_text_address(addr))
  39                                 return true;
  40                 }
  41
  42                 state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
  43
  44         } while (!get_stack_info(state->sp, state->task, info,
  45                                  &state->stack_mask));
  46
  47         return false;
  48 }
  49 EXPORT_SYMBOL_GPL(unwind_next_frame);
  50
  51 void __unwind_start(struct unwind_state *state, struct task_struct *task,
  52                     struct pt_regs *regs, unsigned long *first_frame)
  53 {
  54         memset(state, 0, sizeof(*state));
  55
  56         state->task = task;
  57         state->sp   = PTR_ALIGN(first_frame, sizeof(long));
  58
  59         get_stack_info(first_frame, state->task, &state->stack_info,
  60                        &state->stack_mask);
  61
  62         /*
  63          * The caller can provide the address of the first frame directly
  64          * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  65          * to start unwinding at.  Skip ahead until we reach it.
  66          */
  67         if (!unwind_done(state) &&
  68             (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  69             !__kernel_text_address(*first_frame)))
  70                 unwind_next_frame(state);
  71 }
  72 EXPORT_SYMBOL_GPL(__unwind_start);