x86/kernel/unwind_guess.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 #include <linux/sched.h>
0003 #include <linux/ftrace.h>
0004 #include <asm/ptrace.h>
0005 #include <asm/bitops.h>
0006 #include <asm/stacktrace.h>
0007 #include <asm/unwind.h>
0008
0009 unsigned long unwind_get_return_address(struct unwind_state *state)
0010 {
0011     unsigned long addr;
0012
0013     if (unwind_done(state))
0014         return 0;
0015
0016     addr = READ_ONCE_NOCHECK(*state->sp);
0017
0018     return unwind_recover_ret_addr(state, addr, state->sp);
0019 }
0020 EXPORT_SYMBOL_GPL(unwind_get_return_address);
0021
0022 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
0023 {
0024     return NULL;
0025 }
0026
0027 bool unwind_next_frame(struct unwind_state *state)
0028 {
0029     struct stack_info *info = &state->stack_info;
0030
0031     if (unwind_done(state))
0032         return false;
0033
0034     do {
0035         for (state->sp++; state->sp < info->end; state->sp++) {
0036             unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
0037
0038             if (__kernel_text_address(addr))
0039                 return true;
0040         }
0041
0042         state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
0043
0044     } while (!get_stack_info(state->sp, state->task, info,
0045                  &state->stack_mask));
0046
0047     return false;
0048 }
0049 EXPORT_SYMBOL_GPL(unwind_next_frame);
0050
0051 void __unwind_start(struct unwind_state *state, struct task_struct *task,
0052             struct pt_regs *regs, unsigned long *first_frame)
0053 {
0054     memset(state, 0, sizeof(*state));
0055
0056     state->task = task;
0057     state->sp   = PTR_ALIGN(first_frame, sizeof(long));
0058
0059     get_stack_info(first_frame, state->task, &state->stack_info,
0060                &state->stack_mask);
0061
0062     /*
0063      * The caller can provide the address of the first frame directly
0064      * (first_frame) or indirectly (regs->sp) to indicate which stack frame
0065      * to start unwinding at.  Skip ahead until we reach it.
0066      */
0067     if (!unwind_done(state) &&
0068         (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
0069         !__kernel_text_address(*first_frame)))
0070         unwind_next_frame(state);
0071 }
0072 EXPORT_SYMBOL_GPL(__unwind_start);