1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_POWERPC_BOOK3S_32_KUP_H
3#define _ASM_POWERPC_BOOK3S_32_KUP_H
4
5#include <asm/bug.h>
6#include <asm/book3s/32/mmu-hash.h>
7#include <asm/mmu.h>
8#include <asm/synch.h>
9
10#ifndef __ASSEMBLY__
11
12#ifdef CONFIG_PPC_KUAP
13
14#include <linux/sched.h>
15
16#define KUAP_NONE	(~0UL)
17
18static __always_inline void kuap_lock_one(unsigned long addr)
19{
20	mtsr(mfsr(addr) | SR_KS, addr);
21	isync();	/* Context sync required after mtsr() */
22}
23
24static __always_inline void kuap_unlock_one(unsigned long addr)
25{
26	mtsr(mfsr(addr) & ~SR_KS, addr);
27	isync();	/* Context sync required after mtsr() */
28}
29
30static __always_inline void uaccess_begin_32s(unsigned long addr)
31{
32	unsigned long tmp;
33
34	asm volatile(ASM_MMU_FTR_IFSET(
35		"mfsrin %0, %1;"
36		"rlwinm %0, %0, 0, %2;"
37		"mtsrin %0, %1;"
38		"isync", "", %3)
39		: "=&r"(tmp)
40		: "r"(addr), "i"(~SR_KS), "i"(MMU_FTR_KUAP)
41		: "memory");
42}
43
44static __always_inline void uaccess_end_32s(unsigned long addr)
45{
46	unsigned long tmp;
47
48	asm volatile(ASM_MMU_FTR_IFSET(
49		"mfsrin %0, %1;"
50		"oris %0, %0, %2;"
51		"mtsrin %0, %1;"
52		"isync", "", %3)
53		: "=&r"(tmp)
54		: "r"(addr), "i"(SR_KS >> 16), "i"(MMU_FTR_KUAP)
55		: "memory");
56}
57
58static __always_inline void __kuap_save_and_lock(struct pt_regs *regs)
59{
60	unsigned long kuap = current->thread.kuap;
61
62	regs->kuap = kuap;
63	if (unlikely(kuap == KUAP_NONE))
64		return;
65
66	current->thread.kuap = KUAP_NONE;
67	kuap_lock_one(kuap);
68}
69#define __kuap_save_and_lock __kuap_save_and_lock
70
71static __always_inline void kuap_user_restore(struct pt_regs *regs)
72{
73}
74
75static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
76{
77	if (unlikely(kuap != KUAP_NONE)) {
78		current->thread.kuap = KUAP_NONE;
79		kuap_lock_one(kuap);
80	}
81
82	if (likely(regs->kuap == KUAP_NONE))
83		return;
84
85	current->thread.kuap = regs->kuap;
86
87	kuap_unlock_one(regs->kuap);
88}
89
90static __always_inline unsigned long __kuap_get_and_assert_locked(void)
91{
92	unsigned long kuap = current->thread.kuap;
93
94	WARN_ON_ONCE(IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && kuap != KUAP_NONE);
95
96	return kuap;
97}
98#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
99
100static __always_inline void allow_user_access(void __user *to, const void __user *from,
101					      u32 size, unsigned long dir)
102{
103	BUILD_BUG_ON(!__builtin_constant_p(dir));
104
105	if (!(dir & KUAP_WRITE))
106		return;
107
108	current->thread.kuap = (__force u32)to;
109	uaccess_begin_32s((__force u32)to);
110}
111
112static __always_inline void prevent_user_access(unsigned long dir)
113{
114	u32 kuap = current->thread.kuap;
115
116	BUILD_BUG_ON(!__builtin_constant_p(dir));
117
118	if (!(dir & KUAP_WRITE))
119		return;
120
121	current->thread.kuap = KUAP_NONE;
122	uaccess_end_32s(kuap);
123}
124
125static __always_inline unsigned long prevent_user_access_return(void)
126{
127	unsigned long flags = current->thread.kuap;
128
129	if (flags != KUAP_NONE) {
130		current->thread.kuap = KUAP_NONE;
131		uaccess_end_32s(flags);
132	}
133
134	return flags;
135}
136
137static __always_inline void restore_user_access(unsigned long flags)
138{
139	if (flags != KUAP_NONE) {
140		current->thread.kuap = flags;
141		uaccess_begin_32s(flags);
142	}
143}
144
145static __always_inline bool
146__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
147{
148	unsigned long kuap = regs->kuap;
149
150	if (!is_write)
151		return false;
152	if (kuap == KUAP_NONE)
153		return true;
154
155	/*
156	 * If faulting address doesn't match unlocked segment, change segment.
157	 * In case of unaligned store crossing two segments, emulate store.
158	 */
159	if ((kuap ^ address) & 0xf0000000) {
160		if (!(kuap & 0x0fffffff) && address > kuap - 4 && fix_alignment(regs)) {
161			regs_add_return_ip(regs, 4);
162			emulate_single_step(regs);
163		} else {
164			regs->kuap = address;
165		}
166	}
167
168	return false;
169}
170
171#endif /* CONFIG_PPC_KUAP */
172
173#endif /* __ASSEMBLY__ */
174
175#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */
176