1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H 3 #define _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H 4 5 #include <linux/const.h> 6 7 #define AMR_KUAP_BLOCK_READ UL(0x4000000000000000) 8 #define AMR_KUAP_BLOCK_WRITE UL(0x8000000000000000) 9 #define AMR_KUAP_BLOCKED (AMR_KUAP_BLOCK_READ | AMR_KUAP_BLOCK_WRITE) 10 #define AMR_KUAP_SHIFT 62 11 12 #ifdef __ASSEMBLY__ 13 14 .macro kuap_restore_amr gpr 15 #ifdef CONFIG_PPC_KUAP 16 BEGIN_MMU_FTR_SECTION_NESTED(67) 17 ld \gpr, STACK_REGS_KUAP(r1) 18 mtspr SPRN_AMR, \gpr 19 END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) 20 #endif 21 .endm 22 23 .macro kuap_check_amr gpr1, gpr2 24 #ifdef CONFIG_PPC_KUAP_DEBUG 25 BEGIN_MMU_FTR_SECTION_NESTED(67) 26 mfspr \gpr1, SPRN_AMR 27 li \gpr2, (AMR_KUAP_BLOCKED >> AMR_KUAP_SHIFT) 28 sldi \gpr2, \gpr2, AMR_KUAP_SHIFT 29 999: tdne \gpr1, \gpr2 30 EMIT_BUG_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE) 31 END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) 32 #endif 33 .endm 34 35 .macro kuap_save_amr_and_lock gpr1, gpr2, use_cr, msr_pr_cr 36 #ifdef CONFIG_PPC_KUAP 37 BEGIN_MMU_FTR_SECTION_NESTED(67) 38 .ifnb \msr_pr_cr 39 bne \msr_pr_cr, 99f 40 .endif 41 mfspr \gpr1, SPRN_AMR 42 std \gpr1, STACK_REGS_KUAP(r1) 43 li \gpr2, (AMR_KUAP_BLOCKED >> AMR_KUAP_SHIFT) 44 sldi \gpr2, \gpr2, AMR_KUAP_SHIFT 45 cmpd \use_cr, \gpr1, \gpr2 46 beq \use_cr, 99f 47 // We don't isync here because we very recently entered via rfid 48 mtspr SPRN_AMR, \gpr2 49 isync 50 99: 51 END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) 52 #endif 53 .endm 54 55 #else /* !__ASSEMBLY__ */ 56 57 #ifdef CONFIG_PPC_KUAP 58 59 #include <asm/reg.h> 60 61 /* 62 * We support individually allowing read or write, but we don't support nesting 63 * because that would require an expensive read/modify write of the AMR. 64 */ 65 66 static inline void set_kuap(unsigned long value) 67 { 68 if (!early_mmu_has_feature(MMU_FTR_RADIX_KUAP)) 69 return; 70 71 /* 72 * ISA v3.0B says we need a CSI (Context Synchronising Instruction) both 73 * before and after the move to AMR. See table 6 on page 1134. 74 */ 75 isync(); 76 mtspr(SPRN_AMR, value); 77 isync(); 78 } 79 80 static inline void allow_user_access(void __user *to, const void __user *from, 81 unsigned long size) 82 { 83 // This is written so we can resolve to a single case at build time 84 if (__builtin_constant_p(to) && to == NULL) 85 set_kuap(AMR_KUAP_BLOCK_WRITE); 86 else if (__builtin_constant_p(from) && from == NULL) 87 set_kuap(AMR_KUAP_BLOCK_READ); 88 else 89 set_kuap(0); 90 } 91 92 static inline void prevent_user_access(void __user *to, const void __user *from, 93 unsigned long size) 94 { 95 set_kuap(AMR_KUAP_BLOCKED); 96 } 97 98 static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) 99 { 100 return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) && 101 (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), 102 "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read"); 103 } 104 #endif /* CONFIG_PPC_KUAP */ 105 106 #endif /* __ASSEMBLY__ */ 107 108 #endif /* _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H */ 109
