1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _ASM_S390_UNWIND_H
 3#define _ASM_S390_UNWIND_H
 4
 5#include <linux/sched.h>
 6#include <linux/ftrace.h>
 7#include <linux/kprobes.h>
 8#include <linux/llist.h>
 9#include <asm/ptrace.h>
10#include <asm/stacktrace.h>
11
12/*
13 * To use the stack unwinder it has to be initialized with unwind_start.
14 * There four combinations for task and regs:
15 * 1) task==NULL, regs==NULL: the unwind starts for the task that is currently
16 *    running, sp/ip picked up from the CPU registers
17 * 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in
18 *    the struct pt_regs of an interrupt frame for the current task
19 * 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with
20 *    the sp picked up from task->thread.ksp and the ip picked up from the
21 *    return address stored by __switch_to
22 * 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt
23 *    frame 'regs' of a inactive task
24 * If 'first_frame' is not zero unwind_start skips unwind frames until it
25 * reaches the specified stack pointer.
26 * The end of the unwinding is indicated with unwind_done, this can be true
27 * right after unwind_start, e.g. with first_frame!=0 that can not be found.
28 * unwind_next_frame skips to the next frame.
29 * Once the unwind is completed unwind_error() can be used to check if there
30 * has been a situation where the unwinder could not correctly understand
31 * the tasks call chain.
32 */
33
34struct unwind_state {
35	struct stack_info stack_info;
36	unsigned long stack_mask;
37	struct task_struct *task;
38	struct pt_regs *regs;
39	unsigned long sp, ip;
40	int graph_idx;
41	struct llist_node *kr_cur;
42	bool reliable;
43	bool error;
44};
45
46/* Recover the return address modified by kretprobe and ftrace_graph. */
47static inline unsigned long unwind_recover_ret_addr(struct unwind_state *state,
48						    unsigned long ip)
49{
50	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *)state->sp);
51	if (is_kretprobe_trampoline(ip))
52		ip = kretprobe_find_ret_addr(state->task, (void *)state->sp, &state->kr_cur);
53	return ip;
54}
55
56void __unwind_start(struct unwind_state *state, struct task_struct *task,
57		    struct pt_regs *regs, unsigned long first_frame);
58bool unwind_next_frame(struct unwind_state *state);
59unsigned long unwind_get_return_address(struct unwind_state *state);
60
61static inline bool unwind_done(struct unwind_state *state)
62{
63	return state->stack_info.type == STACK_TYPE_UNKNOWN;
64}
65
66static inline bool unwind_error(struct unwind_state *state)
67{
68	return state->error;
69}
70
71static __always_inline void unwind_start(struct unwind_state *state,
72					 struct task_struct *task,
73					 struct pt_regs *regs,
74					 unsigned long first_frame)
75{
76	task = task ?: current;
77	first_frame = first_frame ?: get_stack_pointer(task, regs);
78	__unwind_start(state, task, regs, first_frame);
79}
80
81static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
82{
83	return unwind_done(state) ? NULL : state->regs;
84}
85
86#define unwind_for_each_frame(state, task, regs, first_frame)	\
87	for (unwind_start(state, task, regs, first_frame);	\
88	     !unwind_done(state);				\
89	     unwind_next_frame(state))
90
91static inline void unwind_init(void) {}
92static inline void unwind_module_init(struct module *mod, void *orc_ip,
93				      size_t orc_ip_size, void *orc,
94				      size_t orc_size) {}
95
96#endif /* _ASM_S390_UNWIND_H */