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h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=fPUSUhFG9xMoZNvTzxCiKap9c369Fj03UMwYjUAwZadKlqvzHztRcbdEf5retEkJ+ G4MLTGHCNZIQGscu6VlrxumG4LdRNa+lwwQoHE3PAodK41Txy2XVyhX1xBvWyUKpOT HV2Agmo5HTrW+zlMTxY7kY5ds0e1HgKBRjMuiXHU= From: Kevin Brodsky Date: Tue, 05 May 2026 17:05:53 +0100 Subject: [PATCH RFC v7 04/24] arm64: Introduce por_elx_set_pkey_perms() helper MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260505-kpkeys-v7-4-20c0bdd97197@arm.com> References: <20260505-kpkeys-v7-0-20c0bdd97197@arm.com> In-Reply-To: <20260505-kpkeys-v7-0-20c0bdd97197@arm.com> To: linux-hardening@vger.kernel.org Cc: Kevin Brodsky , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , Ryan Roberts , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Lorenzo Stoakes , Thomas Gleixner , Vlastimil Babka X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; 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Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/por.h | 7 +++++++ arch/arm64/mm/mmu.c | 26 ++++++++++---------------- 2 files changed, 17 insertions(+), 16 deletions(-) diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h index d913d5b529e4..bffb4d2b1246 100644 --- a/arch/arm64/include/asm/por.h +++ b/arch/arm64/include/asm/por.h @@ -31,4 +31,11 @@ static inline bool por_elx_allows_exec(u64 por, u8 pkey) return perm & POE_X; } +static inline u64 por_elx_set_pkey_perms(u64 por, u8 pkey, u64 perms) +{ + u64 shift = POR_ELx_PERM_SHIFT(pkey); + + return (por & ~(POE_MASK << shift)) | (perms << shift); +} + #endif /* _ASM_ARM64_POR_H */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index dd85e093ffdb..493310cf0486 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -2339,8 +2339,8 @@ void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp) #ifdef CONFIG_ARCH_HAS_PKEYS int arch_set_user_pkey_access(int pkey, unsigned long init_val) { - u64 new_por; - u64 old_por; + u64 new_perms; + u64 por; if (!system_supports_poe()) return -ENOSPC; @@ -2354,25 +2354,19 @@ int arch_set_user_pkey_access(int pkey, unsigned long init_val) return -EINVAL; /* Set the bits we need in POR: */ - new_por = POE_RWX; + new_perms = POE_RWX; if (init_val & PKEY_DISABLE_WRITE) - new_por &= ~POE_W; + new_perms &= ~POE_W; if (init_val & PKEY_DISABLE_ACCESS) - new_por &= ~POE_RW; + new_perms &= ~POE_RW; if (init_val & PKEY_DISABLE_READ) - new_por &= ~POE_R; + new_perms &= ~POE_R; if (init_val & PKEY_DISABLE_EXECUTE) - new_por &= ~POE_X; + new_perms &= ~POE_X; - /* Shift the bits in to the correct place in POR for pkey: */ - new_por = POR_ELx_PERM_PREP(pkey, new_por); - - /* Get old POR and mask off any old bits in place: */ - old_por = read_sysreg_s(SYS_POR_EL0); - old_por &= ~(POE_MASK << POR_ELx_PERM_SHIFT(pkey)); - - /* Write old part along with new part: */ - write_sysreg_s(old_por | new_por, SYS_POR_EL0); + por = read_sysreg_s(SYS_POR_EL0); + por = por_elx_set_pkey_perms(por, pkey, new_perms); + write_sysreg_s(por, SYS_POR_EL0); return 0; } -- 2.51.2