1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Most of this ideas comes from x86.
4  *
5  * Copyright (C) 2022 Loongson Technology Corporation Limited
6  */
7 #ifndef _ASM_UNWIND_H
8 #define _ASM_UNWIND_H
9 
10 #include <linux/sched.h>
11 #include <linux/ftrace.h>
12 
13 #include <asm/ptrace.h>
14 #include <asm/stacktrace.h>
15 
16 enum unwinder_type {
17 	UNWINDER_GUESS,
18 	UNWINDER_PROLOGUE,
19 };
20 
21 struct unwind_state {
22 	char type; /* UNWINDER_XXX */
23 	struct stack_info stack_info;
24 	struct task_struct *task;
25 	bool first, error, reset;
26 	int graph_idx;
27 	unsigned long sp, pc, ra;
28 };
29 
30 bool default_next_frame(struct unwind_state *state);
31 
32 void unwind_start(struct unwind_state *state,
33 		  struct task_struct *task, struct pt_regs *regs);
34 bool unwind_next_frame(struct unwind_state *state);
35 unsigned long unwind_get_return_address(struct unwind_state *state);
36 
unwind_done(struct unwind_state * state)37 static inline bool unwind_done(struct unwind_state *state)
38 {
39 	return state->stack_info.type == STACK_TYPE_UNKNOWN;
40 }
41 
unwind_error(struct unwind_state * state)42 static inline bool unwind_error(struct unwind_state *state)
43 {
44 	return state->error;
45 }
46 
47 #define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
48 
unwind_graph_addr(struct unwind_state * state,unsigned long pc,unsigned long cfa)49 static inline unsigned long unwind_graph_addr(struct unwind_state *state,
50 					unsigned long pc, unsigned long cfa)
51 {
52 	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
53 				     pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
54 }
55 
__unwind_start(struct unwind_state * state,struct task_struct * task,struct pt_regs * regs)56 static __always_inline void __unwind_start(struct unwind_state *state,
57 					struct task_struct *task, struct pt_regs *regs)
58 {
59 	memset(state, 0, sizeof(*state));
60 	if (regs) {
61 		state->sp = regs->regs[3];
62 		state->pc = regs->csr_era;
63 		state->ra = regs->regs[1];
64 	} else if (task && task != current) {
65 		state->sp = thread_saved_fp(task);
66 		state->pc = thread_saved_ra(task);
67 		state->ra = 0;
68 	} else {
69 		state->sp = (unsigned long)__builtin_frame_address(0);
70 		state->pc = (unsigned long)__builtin_return_address(0);
71 		state->ra = 0;
72 	}
73 	state->task = task;
74 	get_stack_info(state->sp, state->task, &state->stack_info);
75 	state->pc = unwind_graph_addr(state, state->pc, state->sp);
76 }
77 
__unwind_get_return_address(struct unwind_state * state)78 static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state)
79 {
80 	return unwind_done(state) ? 0 : state->pc;
81 }
82 #endif /* _ASM_UNWIND_H */
83