1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4  */
5 #ifndef _ASM_PTRACE_H
6 #define _ASM_PTRACE_H
7 
8 #include <asm/page.h>
9 #include <asm/thread_info.h>
10 #include <uapi/asm/ptrace.h>
11 
12 /*
13  * This struct defines the way the registers are stored on the stack during
14  * a system call/exception. If you add a register here, please also add it to
15  * regoffset_table[] in arch/loongarch/kernel/ptrace.c.
16  */
17 struct pt_regs {
18 	/* Main processor registers. */
19 	unsigned long regs[32];
20 
21 	/* Original syscall arg0. */
22 	unsigned long orig_a0;
23 
24 	/* Special CSR registers. */
25 	unsigned long csr_era;
26 	unsigned long csr_badvaddr;
27 	unsigned long csr_crmd;
28 	unsigned long csr_prmd;
29 	unsigned long csr_euen;
30 	unsigned long csr_ecfg;
31 	unsigned long csr_estat;
32 	unsigned long __last[];
33 } __aligned(8);
34 
35 static inline int regs_irqs_disabled(struct pt_regs *regs)
36 {
37 	return arch_irqs_disabled_flags(regs->csr_prmd);
38 }
39 
40 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
41 {
42 	return regs->regs[3];
43 }
44 
45 /*
46  * Don't use asm-generic/ptrace.h it defines FP accessors that don't make
47  * sense on LoongArch.  We rather want an error if they get invoked.
48  */
49 
50 static inline void instruction_pointer_set(struct pt_regs *regs, unsigned long val)
51 {
52 	regs->csr_era = val;
53 }
54 
55 /* Query offset/name of register from its name/offset */
56 extern int regs_query_register_offset(const char *name);
57 #define MAX_REG_OFFSET (offsetof(struct pt_regs, __last))
58 
59 /**
60  * regs_get_register() - get register value from its offset
61  * @regs:       pt_regs from which register value is gotten.
62  * @offset:     offset number of the register.
63  *
64  * regs_get_register returns the value of a register. The @offset is the
65  * offset of the register in struct pt_regs address which specified by @regs.
66  * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
67  */
68 static inline unsigned long regs_get_register(struct pt_regs *regs, unsigned int offset)
69 {
70 	if (unlikely(offset > MAX_REG_OFFSET))
71 		return 0;
72 
73 	return *(unsigned long *)((unsigned long)regs + offset);
74 }
75 
76 /**
77  * regs_within_kernel_stack() - check the address in the stack
78  * @regs:       pt_regs which contains kernel stack pointer.
79  * @addr:       address which is checked.
80  *
81  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
82  * If @addr is within the kernel stack, it returns true. If not, returns false.
83  */
84 static inline int regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
85 {
86 	return ((addr & ~(THREAD_SIZE - 1))  ==
87 		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
88 }
89 
90 /**
91  * regs_get_kernel_stack_nth() - get Nth entry of the stack
92  * @regs:       pt_regs which contains kernel stack pointer.
93  * @n:          stack entry number.
94  *
95  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
96  * is specified by @regs. If the @n th entry is NOT in the kernel stack,
97  * this returns 0.
98  */
99 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
100 {
101 	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
102 
103 	addr += n;
104 	if (regs_within_kernel_stack(regs, (unsigned long)addr))
105 		return *addr;
106 	else
107 		return 0;
108 }
109 
110 struct task_struct;
111 
112 /*
113  * Does the process account for user or for system time?
114  */
115 #define user_mode(regs) (((regs)->csr_prmd & PLV_MASK) == PLV_USER)
116 
117 static inline long regs_return_value(struct pt_regs *regs)
118 {
119 	return regs->regs[4];
120 }
121 
122 #define instruction_pointer(regs) ((regs)->csr_era)
123 #define profile_pc(regs) instruction_pointer(regs)
124 
125 extern void die(const char *, struct pt_regs *) __noreturn;
126 
127 static inline void die_if_kernel(const char *str, struct pt_regs *regs)
128 {
129 	if (unlikely(!user_mode(regs)))
130 		die(str, regs);
131 }
132 
133 #define current_pt_regs()						\
134 ({									\
135 	unsigned long sp = (unsigned long)__builtin_frame_address(0);	\
136 	(struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1) - 1;		\
137 })
138 
139 /* Helpers for working with the user stack pointer */
140 
141 static inline unsigned long user_stack_pointer(struct pt_regs *regs)
142 {
143 	return regs->regs[3];
144 }
145 
146 static inline void user_stack_pointer_set(struct pt_regs *regs,
147 	unsigned long val)
148 {
149 	regs->regs[3] = val;
150 }
151 
152 #endif /* _ASM_PTRACE_H */
153