1a6c401c2c
commit 228a26b912287934789023b4132ba76065d9491c upstream.
Future CPUs may implement a clearbhb instruction that is sufficient
to mitigate SpectreBHB. CPUs that implement this instruction, but
not CSV2.3 must be affected by Spectre-BHB.
Add support to use this instruction as the BHB mitigation on CPUs
that support it. The instruction is in the hint space so it will
be treated by a NOP as older CPUs.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
[ modified for stable: Use a KVM vector template instead of alternatives ]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: ed5dec3fae
Git-repo: https://android.googlesource.com/kernel/common/
Change-Id: I78e5a1888e44ef45294ed35226c4cce43f249126
Signed-off-by: Kishor Krishna Bhat <quic_kishkris@quicinc.com>
75 lines
1.8 KiB
C
75 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2022 ARM Ltd.
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*/
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#ifndef __ASM_VECTORS_H
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#define __ASM_VECTORS_H
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#include <linux/bug.h>
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#include <linux/percpu.h>
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#include <asm/fixmap.h>
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#include <asm/mmu.h>
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extern char vectors[];
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extern char tramp_vectors[];
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extern char __bp_harden_el1_vectors[];
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/*
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* Note: the order of this enum corresponds to two arrays in entry.S:
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* tramp_vecs and __bp_harden_el1_vectors. By default the canonical
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* 'full fat' vectors are used directly.
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*/
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enum arm64_bp_harden_el1_vectors {
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#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
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/*
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* Perform the BHB loop mitigation, before branching to the canonical
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* vectors.
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*/
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EL1_VECTOR_BHB_LOOP,
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/*
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* Make the SMC call for firmware mitigation, before branching to the
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* canonical vectors.
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*/
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EL1_VECTOR_BHB_FW,
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/*
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* Use the ClearBHB instruction, before branching to the canonical
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* vectors.
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*/
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EL1_VECTOR_BHB_CLEAR_INSN,
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#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
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/*
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* Remap the kernel before branching to the canonical vectors.
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*/
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EL1_VECTOR_KPTI,
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};
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#ifndef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
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#define EL1_VECTOR_BHB_LOOP -1
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#define EL1_VECTOR_BHB_FW -1
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#define EL1_VECTOR_BHB_CLEAR_INSN -1
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#endif /* !CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
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/* The vectors to use on return from EL0. e.g. to remap the kernel */
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DECLARE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector);
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#ifndef CONFIG_UNMAP_KERNEL_AT_EL0
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#define TRAMP_VALIAS 0
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#endif
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static inline const char *
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arm64_get_bp_hardening_vector(enum arm64_bp_harden_el1_vectors slot)
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{
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if (arm64_kernel_unmapped_at_el0())
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return (char *)TRAMP_VALIAS + SZ_2K * slot;
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WARN_ON_ONCE(slot == EL1_VECTOR_KPTI);
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return __bp_harden_el1_vectors + SZ_2K * slot;
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}
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#endif /* __ASM_VECTORS_H */
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