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 18 static __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 24 static __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 30 static __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 44 static __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 58 static __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 71 static __always_inline void kuap_user_restore(struct pt_regs *regs) 72 { 73 } 74 75 static __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 90 static __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 99 100 static __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 } 111 112 static __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 } 124 125 static __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 } 136 137 static __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 } 144 145 static __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