From: Ard Biesheuvel <ardb@google.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v2 1/3] arm64: Avoid enabling KPTI unnecessarily
Date: Mon, 27 Nov 2023 13:00:51 +0100 [thread overview]
Message-ID: <20231127120049.2258650-6-ardb@google.com> (raw)
In-Reply-To: <20231127120049.2258650-5-ardb@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
Commit 42c5a3b04bf6 refactored the KPTI init code in a way that results
in the use of non-global kernel mappings even on systems that have no
need for it, and even when KPTI has been disabled explicitly via the
command line.
Ensure that this only happens when we have decided (based on the
detected system-wide CPU features) that KPTI should be enabled.
Fixes: 42c5a3b04bf6 ("arm64: Split kpti_install_ng_mappings()")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/kernel/cpufeature.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 646591c67e7a..91d2d6714969 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1839,6 +1839,10 @@ static int __init __kpti_install_ng_mappings(void *__unused)
static void __init kpti_install_ng_mappings(void)
{
+ /* Check whether KPTI is going to be used */
+ if (!cpus_have_cap(ARM64_UNMAP_KERNEL_AT_EL0))
+ return;
+
/*
* We don't need to rewrite the page-tables if either we've done
* it already or we have KASLR enabled and therefore have not
--
2.43.0.rc1.413.gea7ed67945-goog
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next prev parent reply other threads:[~2023-11-27 12:01 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-27 12:00 [PATCH v2 0/3] arm64 kpti fixes Ard Biesheuvel
2023-11-27 12:00 ` Ard Biesheuvel [this message]
2023-11-27 15:48 ` [PATCH v2 1/3] arm64: Avoid enabling KPTI unnecessarily Will Deacon
2023-11-27 15:52 ` Ard Biesheuvel
2023-11-27 16:31 ` Will Deacon
2023-11-27 16:39 ` Ard Biesheuvel
2023-11-27 16:41 ` Will Deacon
2023-11-27 17:49 ` Mark Rutland
2023-11-28 11:03 ` Will Deacon
2023-11-28 14:13 ` Mark Rutland
2023-12-11 11:39 ` Will Deacon
2023-12-12 17:16 ` Mark Rutland
2023-11-28 11:06 ` Will Deacon
2023-11-27 12:00 ` [PATCH v2 2/3] arm64: mm: Only map KPTI trampoline if it is going to be used Ard Biesheuvel
2023-11-27 12:00 ` [PATCH v2 3/3] arm64: Kconfig: drop KAISER reference from KPTI option description Ard Biesheuvel
2023-11-27 12:47 ` [PATCH v2 0/3] arm64 kpti fixes Mark Rutland
2023-11-30 19:14 ` (subset) " Catalin Marinas
2023-12-11 20:27 ` Will Deacon
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