1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_UNWIND_H
3 #define _ASM_X86_UNWIND_H
4 
5 #include <linux/sched.h>
6 #include <linux/ftrace.h>
7 #include <linux/rethook.h>
8 #include <asm/ptrace.h>
9 #include <asm/stacktrace.h>
10 
11 #define IRET_FRAME_OFFSET (offsetof(struct pt_regs, ip))
12 #define IRET_FRAME_SIZE   (sizeof(struct pt_regs) - IRET_FRAME_OFFSET)
13 
14 struct unwind_state {
15 	struct stack_info stack_info;
16 	unsigned long stack_mask;
17 	struct task_struct *task;
18 	int graph_idx;
19 #if defined(CONFIG_RETHOOK)
20 	struct llist_node *kr_cur;
21 #endif
22 	bool error;
23 #if defined(CONFIG_UNWINDER_ORC)
24 	bool signal, full_regs;
25 	unsigned long sp, bp, ip;
26 	struct pt_regs *regs, *prev_regs;
27 #elif defined(CONFIG_UNWINDER_FRAME_POINTER)
28 	bool got_irq;
29 	unsigned long *bp, *orig_sp, ip;
30 	/*
31 	 * If non-NULL: The current frame is incomplete and doesn't contain a
32 	 * valid BP. When looking for the next frame, use this instead of the
33 	 * non-existent saved BP.
34 	 */
35 	unsigned long *next_bp;
36 	struct pt_regs *regs;
37 #else
38 	unsigned long *sp;
39 #endif
40 };
41 
42 void __unwind_start(struct unwind_state *state, struct task_struct *task,
43 		    struct pt_regs *regs, unsigned long *first_frame);
44 bool unwind_next_frame(struct unwind_state *state);
45 unsigned long unwind_get_return_address(struct unwind_state *state);
46 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state);
47 
unwind_done(struct unwind_state * state)48 static inline bool unwind_done(struct unwind_state *state)
49 {
50 	return state->stack_info.type == STACK_TYPE_UNKNOWN;
51 }
52 
unwind_error(struct unwind_state * state)53 static inline bool unwind_error(struct unwind_state *state)
54 {
55 	return state->error;
56 }
57 
58 static inline
unwind_start(struct unwind_state * state,struct task_struct * task,struct pt_regs * regs,unsigned long * first_frame)59 void unwind_start(struct unwind_state *state, struct task_struct *task,
60 		  struct pt_regs *regs, unsigned long *first_frame)
61 {
62 	first_frame = first_frame ? : get_stack_pointer(task, regs);
63 
64 	__unwind_start(state, task, regs, first_frame);
65 }
66 
67 #if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
68 /*
69  * If 'partial' returns true, only the iret frame registers are valid.
70  */
unwind_get_entry_regs(struct unwind_state * state,bool * partial)71 static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
72 						    bool *partial)
73 {
74 	if (unwind_done(state))
75 		return NULL;
76 
77 	if (partial) {
78 #ifdef CONFIG_UNWINDER_ORC
79 		*partial = !state->full_regs;
80 #else
81 		*partial = false;
82 #endif
83 	}
84 
85 	return state->regs;
86 }
87 #else
unwind_get_entry_regs(struct unwind_state * state,bool * partial)88 static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
89 						    bool *partial)
90 {
91 	return NULL;
92 }
93 #endif
94 
95 #ifdef CONFIG_UNWINDER_ORC
96 void unwind_init(void);
97 void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
98 			void *orc, size_t orc_size);
99 #else
unwind_init(void)100 static inline void unwind_init(void) {}
101 static inline
unwind_module_init(struct module * mod,void * orc_ip,size_t orc_ip_size,void * orc,size_t orc_size)102 void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
103 			void *orc, size_t orc_size) {}
104 #endif
105 
106 static inline
unwind_recover_rethook(struct unwind_state * state,unsigned long addr,unsigned long * addr_p)107 unsigned long unwind_recover_rethook(struct unwind_state *state,
108 				     unsigned long addr, unsigned long *addr_p)
109 {
110 #ifdef CONFIG_RETHOOK
111 	if (is_rethook_trampoline(addr))
112 		return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
113 					     &state->kr_cur);
114 #endif
115 	return addr;
116 }
117 
118 /* Recover the return address modified by rethook and ftrace_graph. */
119 static inline
unwind_recover_ret_addr(struct unwind_state * state,unsigned long addr,unsigned long * addr_p)120 unsigned long unwind_recover_ret_addr(struct unwind_state *state,
121 				     unsigned long addr, unsigned long *addr_p)
122 {
123 	unsigned long ret;
124 
125 	ret = ftrace_graph_ret_addr(state->task, &state->graph_idx,
126 				    addr, addr_p);
127 	return unwind_recover_rethook(state, ret, addr_p);
128 }
129 
130 /*
131  * This disables KASAN checking when reading a value from another task's stack,
132  * since the other task could be running on another CPU and could have poisoned
133  * the stack in the meantime.
134  */
135 #define READ_ONCE_TASK_STACK(task, x)			\
136 ({							\
137 	unsigned long val;				\
138 	if (task == current)				\
139 		val = READ_ONCE(x);			\
140 	else						\
141 		val = READ_ONCE_NOCHECK(x);		\
142 	val;						\
143 })
144 
task_on_another_cpu(struct task_struct * task)145 static inline bool task_on_another_cpu(struct task_struct *task)
146 {
147 #ifdef CONFIG_SMP
148 	return task != current && task->on_cpu;
149 #else
150 	return false;
151 #endif
152 }
153 
154 #endif /* _ASM_X86_UNWIND_H */
155