arch/loongarch/kernel/unwind_guess.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2022 Loongson Technology Corporation Limited
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/ftrace.h>
   7
   8 #include <asm/unwind.h>
   9
  10 unsigned long unwind_get_return_address(struct unwind_state *state)
  11 {
  12         if (unwind_done(state))
  13                 return 0;
  14         else if (state->first)
  15                 return state->pc;
  16
  17         return *(unsigned long *)(state->sp);
  18 }
  19 EXPORT_SYMBOL_GPL(unwind_get_return_address);
  20
  21 void unwind_start(struct unwind_state *state, struct task_struct *task,
  22                     struct pt_regs *regs)
  23 {
  24         memset(state, 0, sizeof(*state));
  25
  26         if (regs) {
  27                 state->sp = regs->regs[3];
  28                 state->pc = regs->csr_era;
  29         }
  30
  31         state->task = task;
  32         state->first = true;
  33
  34         get_stack_info(state->sp, state->task, &state->stack_info);
  35
  36         if (!unwind_done(state) && !__kernel_text_address(state->pc))
  37                 unwind_next_frame(state);
  38 }
  39 EXPORT_SYMBOL_GPL(unwind_start);
  40
  41 bool unwind_next_frame(struct unwind_state *state)
  42 {
  43         struct stack_info *info = &state->stack_info;
  44         unsigned long addr;
  45
  46         if (unwind_done(state))
  47                 return false;
  48
  49         if (state->first)
  50                 state->first = false;
  51
  52         do {
  53                 for (state->sp += sizeof(unsigned long);
  54                      state->sp < info->end;
  55                      state->sp += sizeof(unsigned long)) {
  56                         addr = *(unsigned long *)(state->sp);
  57                         state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
  58                                         addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
  59                         if (__kernel_text_address(addr))
  60                                 return true;
  61                 }
  62
  63                 state->sp = info->next_sp;
  64
  65         } while (!get_stack_info(state->sp, state->task, info));
  66
  67         return false;
  68 }
  69 EXPORT_SYMBOL_GPL(unwind_next_frame);