[RFC PATCH v3 07/15] arm64: Enable kpkeys
From: Kevin Brodsky <hidden>
Date: 2025-02-03 10:20:09
Also in:
linux-hardening, linux-mm, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
This is the final step to enable kpkeys on arm64. We enable POE at EL1 by setting TCR2_EL1.POE, and initialise POR_EL1 so that it enables access to the default pkey/POIndex (default kpkeys level). An ISB is added so that POE restrictions are enforced immediately. Having done this, we can now select ARCH_HAS_KPKEYS if ARM64_POE is enabled. Signed-off-by: Kevin Brodsky <redacted> --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/cpufeature.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fcdd0ed3eca8..34f15348ada8 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig@@ -2186,6 +2186,7 @@ config ARM64_POE def_bool y select ARCH_USES_HIGH_VMA_FLAGS select ARCH_HAS_PKEYS + select ARCH_HAS_KPKEYS help The Permission Overlay Extension is used to implement Memory Protection Keys. Memory Protection Keys provides a mechanism for
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4eb7c6698ae4..28b8c93c60c7 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c@@ -76,6 +76,7 @@ #include <linux/kasan.h> #include <linux/percpu.h> #include <linux/sched/isolation.h> +#include <linux/kpkeys.h> #include <asm/cpu.h> #include <asm/cpufeature.h>
@@ -2385,8 +2386,10 @@ static void cpu_enable_mops(const struct arm64_cpu_capabilities *__unused) #ifdef CONFIG_ARM64_POE static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused) { - sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE); + write_sysreg_s(por_set_kpkeys_level(0, KPKEYS_LVL_DEFAULT), SYS_POR_EL1); + sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE | TCR2_EL1_POE); sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_E0POE); + isb(); } #endif
--
2.47.0