LXR linux/arch/x86/kernel/unwind

   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
   9unsigned 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 ftrace_graph_ret_addr(state->task, &state->graph_idx,
  19                                     addr, state->sp);
  20}
  21EXPORT_SYMBOL_GPL(unwind_get_return_address);
  22
  23unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
  24{
  25        return NULL;
  26}
  27
  28bool unwind_next_frame(struct unwind_state *state)
  29{
  30        struct stack_info *info = &state->stack_info;
  31
  32        if (unwind_done(state))
  33                return false;
  34
  35        do {
  36                for (state->sp++; state->sp < info->end; state->sp++) {
  37                        unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
  38
  39                        if (__kernel_text_address(addr))
  40                                return true;
  41                }
  42
  43                state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
  44
  45        } while (!get_stack_info(state->sp, state->task, info,
  46                                 &state->stack_mask));
  47
  48        return false;
  49}
  50EXPORT_SYMBOL_GPL(unwind_next_frame);
  51
  52void __unwind_start(struct unwind_state *state, struct task_struct *task,
  53                    struct pt_regs *regs, unsigned long *first_frame)
  54{
  55        memset(state, 0, sizeof(*state));
  56
  57        state->task = task;
  58        state->sp   = PTR_ALIGN(first_frame, sizeof(long));
  59
  60        get_stack_info(first_frame, state->task, &state->stack_info,
  61                       &state->stack_mask);
  62
  63        /*
  64         * The caller can provide the address of the first frame directly
  65         * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  66         * to start unwinding at.  Skip ahead until we reach it.
  67         */
  68        if (!unwind_done(state) &&
  69            (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  70            !__kernel_text_address(*first_frame)))
  71                unwind_next_frame(state);
  72}
  73EXPORT_SYMBOL_GPL(__unwind_start);
  74