arch/arm64/include/asm/vectors.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2022 ARM Ltd.
   4  */
   5 #ifndef __ASM_VECTORS_H
   6 #define __ASM_VECTORS_H
   7
   8 #include <linux/bug.h>
   9 #include <linux/percpu.h>
  10
  11 #include <asm/fixmap.h>
  12 #include <asm/mmu.h>
  13
  14 extern char vectors[];
  15 extern char tramp_vectors[];
  16 extern char __bp_harden_el1_vectors[];
  17
  18 /*
  19  * Note: the order of this enum corresponds to two arrays in entry.S:
  20  * tramp_vecs and __bp_harden_el1_vectors. By default the canonical
  21  * 'full fat' vectors are used directly.
  22  */
  23 enum arm64_bp_harden_el1_vectors {
  24 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
  25         /*
  26          * Perform the BHB loop mitigation, before branching to the canonical
  27          * vectors.
  28          */
  29         EL1_VECTOR_BHB_LOOP,
  30
  31         /*
  32          * Make the SMC call for firmware mitigation, before branching to the
  33          * canonical vectors.
  34          */
  35         EL1_VECTOR_BHB_FW,
  36
  37         /*
  38          * Use the ClearBHB instruction, before branching to the canonical
  39          * vectors.
  40          */
  41         EL1_VECTOR_BHB_CLEAR_INSN,
  42 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
  43
  44         /*
  45          * Remap the kernel before branching to the canonical vectors.
  46          */
  47         EL1_VECTOR_KPTI,
  48 };
  49
  50 #ifndef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
  51 #define EL1_VECTOR_BHB_LOOP             -1
  52 #define EL1_VECTOR_BHB_FW               -1
  53 #define EL1_VECTOR_BHB_CLEAR_INSN       -1
  54 #endif /* !CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
  55
  56 /* The vectors to use on return from EL0. e.g. to remap the kernel */
  57 DECLARE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector);
  58
  59 #ifndef CONFIG_UNMAP_KERNEL_AT_EL0
  60 #define TRAMP_VALIAS    0
  61 #endif
  62
  63 static inline const char *
  64 arm64_get_bp_hardening_vector(enum arm64_bp_harden_el1_vectors slot)
  65 {
  66         if (arm64_kernel_unmapped_at_el0())
  67                 return (char *)TRAMP_VALIAS + SZ_2K * slot;
  68
  69         WARN_ON_ONCE(slot == EL1_VECTOR_KPTI);
  70
  71         return __bp_harden_el1_vectors + SZ_2K * slot;
  72 }
  73
  74 #endif /* __ASM_VECTORS_H */