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 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, unsigned long dir) 101 { 102 BUILD_BUG_ON(!__builtin_constant_p(dir)); 103 104 if (!(dir & KUAP_WRITE)) 105 return; 106 107 current->thread.kuap = (__force u32)to; 108 uaccess_begin_32s((__force u32)to); 109 } 110 111 static __always_inline void prevent_user_access(unsigned long dir) 112 { 113 u32 kuap = current->thread.kuap; 114 115 BUILD_BUG_ON(!__builtin_constant_p(dir)); 116 117 if (!(dir & KUAP_WRITE)) 118 return; 119 120 current->thread.kuap = KUAP_NONE; 121 uaccess_end_32s(kuap); 122 } 123 124 static __always_inline unsigned long prevent_user_access_return(void) 125 { 126 unsigned long flags = current->thread.kuap; 127 128 if (flags != KUAP_NONE) { 129 current->thread.kuap = KUAP_NONE; 130 uaccess_end_32s(flags); 131 } 132 133 return flags; 134 } 135 136 static __always_inline void restore_user_access(unsigned long flags) 137 { 138 if (flags != KUAP_NONE) { 139 current->thread.kuap = flags; 140 uaccess_begin_32s(flags); 141 } 142 } 143 144 static __always_inline bool 145 __bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) 146 { 147 unsigned long kuap = regs->kuap; 148 149 if (!is_write) 150 return false; 151 if (kuap == KUAP_NONE) 152 return true; 153 154 /* 155 * If faulting address doesn't match unlocked segment, change segment. 156 * In case of unaligned store crossing two segments, emulate store. 157 */ 158 if ((kuap ^ address) & 0xf0000000) { 159 if (!(kuap & 0x0fffffff) && address > kuap - 4 && fix_alignment(regs)) { 160 regs_add_return_ip(regs, 4); 161 emulate_single_step(regs); 162 } else { 163 regs->kuap = address; 164 } 165 } 166 167 return false; 168 } 169 170 #endif /* CONFIG_PPC_KUAP */ 171 172 #endif /* __ASSEMBLER__ */ 173 174 #endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */ 175