bd09128d16
The Spectre-BHB workaround adds a firmware call to the vectors. This is needed on some CPUs, but not others. To avoid the unaffected CPU in a big/little pair from making the firmware call, create per cpu vectors. The per-cpu vectors only apply when returning from EL0. Systems using KPTI can use the canonical 'full-fat' vectors directly at EL1, the trampoline exit code will switch to this_cpu_vector on exit to EL0. Systems not using KPTI should always use this_cpu_vector. this_cpu_vector will point at a vector in tramp_vecs or __bp_harden_el1_vectors, depending on whether KPTI is in use. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: James Morse <james.morse@arm.com>
62 lines
1.4 KiB
C
62 lines
1.4 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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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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#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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/* 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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