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
34 struct 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. */
unwind_recover_ret_addr(struct unwind_state * state,unsigned long ip)47 static 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
56 void __unwind_start(struct unwind_state *state, struct task_struct *task,
57 struct pt_regs *regs, unsigned long first_frame);
58 bool unwind_next_frame(struct unwind_state *state);
59 unsigned long unwind_get_return_address(struct unwind_state *state);
60
unwind_done(struct unwind_state * state)61 static inline bool unwind_done(struct unwind_state *state)
62 {
63 return state->stack_info.type == STACK_TYPE_UNKNOWN;
64 }
65
unwind_error(struct unwind_state * state)66 static inline bool unwind_error(struct unwind_state *state)
67 {
68 return state->error;
69 }
70
unwind_start(struct unwind_state * state,struct task_struct * task,struct pt_regs * regs,unsigned long first_frame)71 static __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
unwind_get_entry_regs(struct unwind_state * state)81 static 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
unwind_init(void)91 static inline void unwind_init(void) {}
unwind_module_init(struct module * mod,void * orc_ip,size_t orc_ip_size,void * orc,size_t orc_size)92 static 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 */
97