From: Kevin Brodsky <kevin.brodsky@arm•com>
To: linux-hardening@vger•kernel.org
Cc: Kevin Brodsky <kevin.brodsky@arm•com>,
Andrew Morton <akpm@linux-foundation•org>,
Andy Lutomirski <luto@kernel•org>,
Catalin Marinas <catalin.marinas@arm•com>,
Dave Hansen <dave.hansen@linux•intel.com>,
"David Hildenbrand (Arm)" <david@kernel•org>,
Ira Weiny <ira.weiny@intel•com>, Jann Horn <jannh@google•com>,
Jeff Xu <jeffxu@chromium•org>, Joey Gouly <joey.gouly@arm•com>,
Kees Cook <kees@kernel•org>, Linus Walleij <linusw@kernel•org>,
Marc Zyngier <maz@kernel•org>, Mark Brown <broonie@kernel•org>,
Matthew Wilcox <willy@infradead•org>,
Maxwell Bland <mbland@motorola•com>,
"Mike Rapoport (IBM)" <rppt@kernel•org>,
Peter Zijlstra <peterz@infradead•org>,
Pierre Langlois <pierre.langlois@arm•com>,
Quentin Perret <qperret@google•com>,
Rick Edgecombe <rick.p.edgecombe@intel•com>,
Ryan Roberts <ryan.roberts@arm•com>,
Vlastimil Babka <vbabka@kernel•org>,
Will Deacon <will@kernel•org>,
Yang Shi <yang@os•amperecomputing.com>,
Yeoreum Yun <yeoreum.yun@arm•com>,
linux-arm-kernel@lists•infradead.org, linux-mm@kvack•org,
x86@kernel•org, Lorenzo Stoakes <ljs@kernel•org>,
Thomas Gleixner <tglx@kernel•org>
Subject: [PATCH RFC v8 05/24] arm64: Implement asm/kpkeys.h using POE
Date: Tue, 26 May 2026 12:15:54 +0100 [thread overview]
Message-ID: <20260526-kpkeys-v8-5-eaaacdacc67c@arm.com> (raw)
In-Reply-To: <20260526-kpkeys-v8-0-eaaacdacc67c@arm.com>
Implement the kpkeys interface if CONFIG_ARM64_POE is enabled.
The permissions for KPKEYS_PKEY_DEFAULT (pkey 0) are set to RWX as
this pkey is also used for code mappings.
To allow <asm/kpkeys.h> to be included from assembly, also add
appropriate #ifdef's to <asm/por.h>.
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm•com>
---
arch/arm64/include/asm/kpkeys.h | 59 +++++++++++++++++++++++++++++++++++++++++
arch/arm64/include/asm/por.h | 4 +++
2 files changed, 63 insertions(+)
diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h
new file mode 100644
index 000000000000..4dbfeb3dfcfe
--- /dev/null
+++ b/arch/arm64/include/asm/kpkeys.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_KPKEYS_H
+#define __ASM_KPKEYS_H
+
+#include <asm/barrier.h>
+#include <asm/cpufeature.h>
+#include <asm/por.h>
+
+#include <asm-generic/kpkeys.h>
+
+/*
+ * 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(KPKEYS_PKEY_DEFAULT, 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, int ctx)
+{
+ por = por_elx_set_pkey_perms(por, KPKEYS_PKEY_DEFAULT, 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 u64 arch_kpkeys_set_context(int ctx)
+{
+ u64 prev_por = read_sysreg_s(SYS_POR_EL1);
+ u64 new_por = por_set_kpkeys_context(prev_por, ctx);
+
+ __kpkeys_set_pkey_reg_nosync(new_por);
+ isb();
+
+ return prev_por;
+}
+
+static __always_inline void arch_kpkeys_restore_pkey_reg(u64 pkey_reg)
+{
+ __kpkeys_set_pkey_reg_nosync(pkey_reg);
+ isb();
+}
+
+#endif /* CONFIG_ARM64_POE */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_KPKEYS_H */
diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h
index bffb4d2b1246..58dce4b8021b 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, u64 perms)
return (por & ~(POE_MASK << shift)) | (perms << shift);
}
+#endif /* __ASSEMBLY__ */
+
#endif /* _ASM_ARM64_POR_H */
--
2.51.2
next prev parent reply other threads:[~2026-05-26 11:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-26 11:15 [PATCH RFC v8 00/24] pkeys-based page table hardening Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 01/24] mm: Introduce kpkeys Kevin Brodsky
2026-05-26 13:17 ` Linus Walleij
2026-05-27 8:24 ` Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 02/24] set_memory: Introduce set_memory_pkey() stub Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 03/24] arm64: mm: Enable overlays for all EL1 indirect permissions Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 04/24] arm64: Introduce por_elx_set_pkey_perms() helper Kevin Brodsky
2026-05-26 11:15 ` Kevin Brodsky [this message]
2026-05-26 11:15 ` [PATCH RFC v8 06/24] arm64: set_memory: Implement set_memory_pkey() Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 07/24] arm64: Context-switch POR_EL1 Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 08/24] arm64: Initialize POR_EL1 register on cpu_resume() Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 09/24] arm64: Enable kpkeys Kevin Brodsky
2026-05-26 11:15 ` [PATCH RFC v8 10/24] memblock: Move INIT_MEMBLOCK_* macros to header Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 11/24] mm: kpkeys: Introduce kpkeys_hardened_pgtables feature Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 12/24] mm: kpkeys: Protect regular page tables Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 13/24] mm: kpkeys: Introduce early page table allocator Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 14/24] mm: kpkeys: Protect vmemmap page tables Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 15/24] mm: kpkeys: Introduce hook for protecting static " Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 16/24] arm64: kpkeys: Implement arch_supports_kpkeys_early() Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 17/24] arm64: kpkeys: Support KPKEYS_CTX_PGTABLES Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 18/24] arm64: kpkeys: Ensure the linear map can be modified Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 19/24] arm64: kpkeys: Protect early page tables Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 20/24] arm64: kpkeys: Protect init_pg_dir Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 21/24] arm64: kpkeys: Guard page table writes Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 22/24] arm64: kpkeys: Batch KPKEYS_CTX_PGTABLES switches Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 23/24] arm64: kpkeys: Enable kpkeys_hardened_pgtables support Kevin Brodsky
2026-05-26 11:16 ` [PATCH RFC v8 24/24] mm: Add basic tests for kpkeys_hardened_pgtables Kevin Brodsky
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