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
  13 extern char vectors[];
  14 extern char tramp_vectors[];
  15 extern char __bp_harden_el1_vectors[];
  16
  17 /*
  18  * Note: the order of this enum corresponds to two arrays in entry.S:
  19  * tramp_vecs and __bp_harden_el1_vectors. By default the canonical
  20  * 'full fat' vectors are used directly.
  21  */
  22 enum arm64_bp_harden_el1_vectors {
  23 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
  24         /*
  25          * Perform the BHB loop mitigation, before branching to the canonical
  26          * vectors.
  27          */
  28         EL1_VECTOR_BHB_LOOP,
  29
  30         /*
  31          * Make the SMC call for firmware mitigation, before branching to the
  32          * canonical vectors.
  33          */
  34         EL1_VECTOR_BHB_FW,
  35
  36         /*
  37          * Use the ClearBHB instruction, before branching to the canonical
  38          * vectors.
  39          */
  40         EL1_VECTOR_BHB_CLEAR_INSN,
  41 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
  42
  43         /*
  44          * Remap the kernel before branching to the canonical vectors.
  45          */
  46         EL1_VECTOR_KPTI,
  47 };
  48
  49 #ifndef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
  50 #define EL1_VECTOR_BHB_LOOP             -1
  51 #define EL1_VECTOR_BHB_FW               -1
  52 #define EL1_VECTOR_BHB_CLEAR_INSN       -1
  53 #endif /* !CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
  54
  55 /* The vectors to use on return from EL0. e.g. to remap the kernel */
  56 DECLARE_PER_CPU_READ_MOSTLY(const char *, this_cpu_vector);
  57
  58 #ifndef CONFIG_UNMAP_KERNEL_AT_EL0
  59 #define TRAMP_VALIAS    0ul
  60 #endif
  61
  62 static inline const char *
  63 arm64_get_bp_hardening_vector(enum arm64_bp_harden_el1_vectors slot)
  64 {
  65         if (cpus_have_cap(ARM64_UNMAP_KERNEL_AT_EL0))
  66                 return (char *)(TRAMP_VALIAS + SZ_2K * slot);
  67
  68         WARN_ON_ONCE(slot == EL1_VECTOR_KPTI);
  69
  70         return __bp_harden_el1_vectors + SZ_2K * slot;
  71 }
  72
  73 #endif /* __ASM_VECTORS_H */