unwind.h

 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
16enum unwinder_type {
17	UNWINDER_GUESS,
18	UNWINDER_PROLOGUE,
19	UNWINDER_ORC,
20};
21
22struct unwind_state {
23	char type; /* UNWINDER_XXX */
24	struct stack_info stack_info;
25	struct task_struct *task;
26	bool first, error, reset;
27	int graph_idx;
28	unsigned long sp, fp, pc, ra;
29};
30
31bool default_next_frame(struct unwind_state *state);
32
33void unwind_start(struct unwind_state *state,
34		  struct task_struct *task, struct pt_regs *regs);
35bool unwind_next_frame(struct unwind_state *state);
36unsigned long unwind_get_return_address(struct unwind_state *state);
37
38static inline bool unwind_done(struct unwind_state *state)
39{
40	return state->stack_info.type == STACK_TYPE_UNKNOWN;
41}
42
43static inline bool unwind_error(struct unwind_state *state)
44{
45	return state->error;
46}
47
48#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
49
50static inline unsigned long unwind_graph_addr(struct unwind_state *state,
51					unsigned long pc, unsigned long cfa)
52{
53	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
54				     pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
55}
56
57static __always_inline void __unwind_start(struct unwind_state *state,
58					struct task_struct *task, struct pt_regs *regs)
59{
60	memset(state, 0, sizeof(*state));
61	if (regs) {
62		state->sp = regs->regs[3];
63		state->pc = regs->csr_era;
64		state->ra = regs->regs[1];
65		state->fp = regs->regs[22];
66	} else if (task && task != current) {
67		state->sp = thread_saved_fp(task);
68		state->pc = thread_saved_ra(task);
69		state->ra = 0;
70		state->fp = 0;
71	} else {
72		state->sp = (unsigned long)__builtin_frame_address(0);
73		state->pc = (unsigned long)__builtin_return_address(0);
74		state->ra = 0;
75		state->fp = 0;
76	}
77	state->task = task;
78	get_stack_info(state->sp, state->task, &state->stack_info);
79	state->pc = unwind_graph_addr(state, state->pc, state->sp);
80}
81
82static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state)
83{
84	if (unwind_done(state))
85		return 0;
86
87	return __kernel_text_address(state->pc) ? state->pc : 0;
88}
89
90#ifdef CONFIG_UNWINDER_ORC
91void unwind_init(void);
92void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size);
93#else
94static inline void unwind_init(void) {}
95static inline void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size) {}
96#endif
97
98#endif /* _ASM_UNWIND_H */