diff options
Diffstat (limited to 'arch/powerpc/include/asm/book3s/64/kup-radix.h')
-rw-r--r-- | arch/powerpc/include/asm/book3s/64/kup-radix.h | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h new file mode 100644 index 000000000000..6d6628424134 --- /dev/null +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -0,0 +1,102 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H +#define _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H + +#include <linux/const.h> + +#define AMR_KUAP_BLOCK_READ UL(0x4000000000000000) +#define AMR_KUAP_BLOCK_WRITE UL(0x8000000000000000) +#define AMR_KUAP_BLOCKED (AMR_KUAP_BLOCK_READ | AMR_KUAP_BLOCK_WRITE) +#define AMR_KUAP_SHIFT 62 + +#ifdef __ASSEMBLY__ + +.macro kuap_restore_amr gpr +#ifdef CONFIG_PPC_KUAP + BEGIN_MMU_FTR_SECTION_NESTED(67) + ld \gpr, STACK_REGS_KUAP(r1) + mtspr SPRN_AMR, \gpr + END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) +#endif +.endm + +.macro kuap_check_amr gpr1, gpr2 +#ifdef CONFIG_PPC_KUAP_DEBUG + BEGIN_MMU_FTR_SECTION_NESTED(67) + mfspr \gpr1, SPRN_AMR + li \gpr2, (AMR_KUAP_BLOCKED >> AMR_KUAP_SHIFT) + sldi \gpr2, \gpr2, AMR_KUAP_SHIFT +999: tdne \gpr1, \gpr2 + EMIT_BUG_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE) + END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) +#endif +.endm + +.macro kuap_save_amr_and_lock gpr1, gpr2, use_cr, msr_pr_cr +#ifdef CONFIG_PPC_KUAP + BEGIN_MMU_FTR_SECTION_NESTED(67) + .ifnb \msr_pr_cr + bne \msr_pr_cr, 99f + .endif + mfspr \gpr1, SPRN_AMR + std \gpr1, STACK_REGS_KUAP(r1) + li \gpr2, (AMR_KUAP_BLOCKED >> AMR_KUAP_SHIFT) + sldi \gpr2, \gpr2, AMR_KUAP_SHIFT + cmpd \use_cr, \gpr1, \gpr2 + beq \use_cr, 99f + // We don't isync here because we very recently entered via rfid + mtspr SPRN_AMR, \gpr2 + isync +99: + END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67) +#endif +.endm + +#else /* !__ASSEMBLY__ */ + +#ifdef CONFIG_PPC_KUAP + +#include <asm/reg.h> + +/* + * We support individually allowing read or write, but we don't support nesting + * because that would require an expensive read/modify write of the AMR. + */ + +static inline void set_kuap(unsigned long value) +{ + if (!mmu_has_feature(MMU_FTR_RADIX_KUAP)) + return; + + /* + * ISA v3.0B says we need a CSI (Context Synchronising Instruction) both + * before and after the move to AMR. See table 6 on page 1134. + */ + isync(); + mtspr(SPRN_AMR, value); + isync(); +} + +static inline void allow_user_access(void __user *to, const void __user *from, + unsigned long size) +{ + // This is written so we can resolve to a single case at build time + if (__builtin_constant_p(to) && to == NULL) + set_kuap(AMR_KUAP_BLOCK_WRITE); + else if (__builtin_constant_p(from) && from == NULL) + set_kuap(AMR_KUAP_BLOCK_READ); + else + set_kuap(0); +} + +static inline void prevent_user_access(void __user *to, const void __user *from, + unsigned long size) +{ + set_kuap(AMR_KUAP_BLOCKED); +} + +#endif /* CONFIG_PPC_KUAP */ + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H */ |