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bh=6wbz7M9AxUaVbPIWUUWjzRRnSMPq0HS+t9xWqqATY50=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=eegD3Q5zeLXme4NvXnUJNYwKafnS1JAt4VVHBEbHdSs/9LuqzzWjqNenBJoOpv+oW UeD15hUuXB2GUF+Nw3cbWEYXVCC9G8Y9+PFLZekCFB3REt156/mNAaAHvbVLijXgkX a4CLhHodZe6F1Gjhm9EgzjUU1gV7P6m3VeSq9A3s= From: Kevin Brodsky Date: Tue, 18 Aug 2026 15:08:47 +0100 Subject: [PATCH RFC v9 05/25] arm64: Implement asm/kpkeys.h using POE MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260818-kpkeys-v9-5-743ad31b2c8f@arm.com> References: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> In-Reply-To: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> To: linux-hardening@vger.kernel.org Cc: Kevin Brodsky , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linu Cherian , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , =?utf-8?q?Pierre-Cl=C3=A9ment_Tosi?= , Quentin Perret , Rick Edgecombe , Ryan Roberts , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Ira Weiny , Lorenzo Stoakes , Thomas Gleixner X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787062276; l=3520; i=kevin.brodsky@arm.com; s=20260427; h=from:subject:message-id; bh=6wbz7M9AxUaVbPIWUUWjzRRnSMPq0HS+t9xWqqATY50=; b=qSs2aR0MM51fpLHnCL+cqiL5CeqWF8AjtCb69VRsQre+Xry4+dqxT+AElsKlSRpe1daufmoo0 DHdsQ6uk7EFBwHC3vYbMZnfyPIBOBhD6kw+KHDnL00yy/Gvme1fBgMK X-Developer-Key: i=kevin.brodsky@arm.com; a=ed25519; pk=N2QG+eJKrvkNovwhhwJhnJ4+ScVfsGCHldmqLfcMTFs= X-Rspam-User: X-Stat-Signature: qks6r6k3g5xh17b8too4q1zbu7yqti1n X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1B182140006 X-HE-Tag: 1787062307-322599 X-HE-Meta: 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 nUqBPH2b dLVqPB7su7BNT1sGSE8w0vbu6yWPrTQcJmn4fGp1fLs/IncWq/R88E02792hW0jvBLwRAkEOEhNmrTmqybCO8cjjtiWUb/dDEHPeYfVLr9QwmXNpjzzPm3YPAcrb+i6LtI8BsV6MzT0QVgc+MW9l0YIO32j35n4hY7grexEpaIq9QjuUvrE+Jx4G0MmW91g6KKiH/feTDMsfTI9l6bGZP6OxhbhMUUjoPKfYl5VATmAMZrhaCVFTgRsCn5OWIINONOn9Y Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Implement the kpkeys interface if CONFIG_ARM64_POE is enabled. The permissions for pkey 0 are set to RWX as this pkey is also used for code mappings. POR_EL1 is left untouched if we have already entered the requested context. To allow to be included from assembly, also add appropriate #ifdef's to . Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/kpkeys.h | 67 +++++++++++++++++++++++++++++++++++ arch/arm64/include/asm/kpkeys_types.h | 15 ++++++++ arch/arm64/include/asm/por.h | 4 +++ 3 files changed, 86 insertions(+) diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h new file mode 100644 index 000000000000..09fd5a849cb0 --- /dev/null +++ b/arch/arm64/include/asm/kpkeys.h @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_KPKEYS_H +#define __ASM_KPKEYS_H + +#include + +#include +#include +#include + +/* + * Equivalent to por_set_kpkeys_context(0, KPKEYS_CTX_DEFAULT), but can also be + * used in assembly. + */ +#define POR_EL1_INIT POR_ELx_PERM_PREP(0, POE_RWX) + +#ifndef __ASSEMBLY__ + +static inline bool arch_supports_kpkeys(void) +{ + return system_supports_poe(); +} + +#ifdef CONFIG_ARM64_POE + +static inline u64 por_set_kpkeys_context(u64 por, enum kpkeys_ctx ctx) +{ + por = por_elx_set_pkey_perms(por, 0, POE_RWX); + + return por; +} + +static __always_inline void __kpkeys_set_pkey_reg_nosync(u64 pkey_reg) +{ + write_sysreg_s(pkey_reg, SYS_POR_EL1); +} + +static __always_inline +struct kpkeys_state arch_kpkeys_enter_context(enum kpkeys_ctx ctx) +{ + const u64 prev_por = read_sysreg_s(SYS_POR_EL1); + const u64 new_por = por_set_kpkeys_context(prev_por, ctx); + + if (prev_por == new_por) + return (struct kpkeys_state) { .entered_context = false }; + + __kpkeys_set_pkey_reg_nosync(new_por); + isb(); + + return (struct kpkeys_state) { + .entered_context = true, + .arch_state.por = prev_por, + }; +} + +static __always_inline +void arch_kpkeys_leave_context(const struct kpkeys_state *state) +{ + __kpkeys_set_pkey_reg_nosync(state->arch_state.por); + isb(); +} + +#endif /* CONFIG_ARM64_POE */ + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_KPKEYS_H */ diff --git a/arch/arm64/include/asm/kpkeys_types.h b/arch/arm64/include/asm/kpkeys_types.h new file mode 100644 index 000000000000..e9c59a26ee7a --- /dev/null +++ b/arch/arm64/include/asm/kpkeys_types.h @@ -0,0 +1,15 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_KPKEYS_TYPES_H +#define __ASM_KPKEYS_TYPES_H + +#include + +#ifndef __ASSEMBLY__ + +struct arch_kpkeys_state { + u64 por; +}; + +#endif /* __ASSEMBLY__ */ + +#endif /* __ASM_KPKEYS_TYPES_H */ diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h index 19b3dd1d43a0..dddabf6ffae6 100644 --- a/arch/arm64/include/asm/por.h +++ b/arch/arm64/include/asm/por.h @@ -10,6 +10,8 @@ #define POR_EL0_INIT POR_ELx_PERM_PREP(0, POE_RWX) +#ifndef __ASSEMBLY__ + static inline bool por_elx_allows_read(u64 por, u8 pkey) { u8 perm = POR_ELx_PERM_GET(pkey, por); @@ -38,4 +40,6 @@ static inline u64 por_elx_set_pkey_perms(u64 por, u8 pkey, u8 perms) return (por & ~(POE_MASK << shift)) | ((u64)perms << shift); } +#endif /* __ASSEMBLY__ */ + #endif /* _ASM_ARM64_POR_H */ -- 2.51.2