kup.h

  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 __ASSEMBLER__
 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 /* __ASSEMBLER__ */
174
175#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */