arch/x86/kernel/paravirt_patch.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/stringify.h>
   3
   4 #include <asm/paravirt.h>
   5 #include <asm/asm-offsets.h>
   6
   7 #define PSTART(d, m)                                                    \
   8         patch_data_##d.m
   9
  10 #define PEND(d, m)                                                      \
  11         (PSTART(d, m) + sizeof(patch_data_##d.m))
  12
  13 #define PATCH(d, m, insn_buff, len)                                             \
  14         paravirt_patch_insns(insn_buff, len, PSTART(d, m), PEND(d, m))
  15
  16 #define PATCH_CASE(ops, m, data, insn_buff, len)                                \
  17         case PARAVIRT_PATCH(ops.m):                                     \
  18                 return PATCH(data, ops##_##m, insn_buff, len)
  19
  20 #ifdef CONFIG_PARAVIRT_XXL
  21 struct patch_xxl {
  22         const unsigned char     irq_irq_disable[1];
  23         const unsigned char     irq_irq_enable[1];
  24         const unsigned char     irq_save_fl[2];
  25         const unsigned char     mmu_read_cr2[3];
  26         const unsigned char     mmu_read_cr3[3];
  27         const unsigned char     mmu_write_cr3[3];
  28         const unsigned char     irq_restore_fl[2];
  29         const unsigned char     cpu_wbinvd[2];
  30         const unsigned char     cpu_usergs_sysret64[6];
  31         const unsigned char     mov64[3];
  32 };
  33
  34 static const struct patch_xxl patch_data_xxl = {
  35         .irq_irq_disable        = { 0xfa },             // cli
  36         .irq_irq_enable         = { 0xfb },             // sti
  37         .irq_save_fl            = { 0x9c, 0x58 },       // pushf; pop %[re]ax
  38         .mmu_read_cr2           = { 0x0f, 0x20, 0xd0 }, // mov %cr2, %[re]ax
  39         .mmu_read_cr3           = { 0x0f, 0x20, 0xd8 }, // mov %cr3, %[re]ax
  40         .mmu_write_cr3          = { 0x0f, 0x22, 0xdf }, // mov %rdi, %cr3
  41         .irq_restore_fl         = { 0x57, 0x9d },       // push %rdi; popfq
  42         .cpu_wbinvd             = { 0x0f, 0x09 },       // wbinvd
  43         .cpu_usergs_sysret64    = { 0x0f, 0x01, 0xf8,
  44                                     0x48, 0x0f, 0x07 }, // swapgs; sysretq
  45         .mov64                  = { 0x48, 0x89, 0xf8 }, // mov %rdi, %rax
  46 };
  47
  48 unsigned int paravirt_patch_ident_64(void *insn_buff, unsigned int len)
  49 {
  50         return PATCH(xxl, mov64, insn_buff, len);
  51 }
  52 # endif /* CONFIG_PARAVIRT_XXL */
  53
  54 #ifdef CONFIG_PARAVIRT_SPINLOCKS
  55 struct patch_lock {
  56         unsigned char queued_spin_unlock[3];
  57         unsigned char vcpu_is_preempted[2];
  58 };
  59
  60 static const struct patch_lock patch_data_lock = {
  61         .vcpu_is_preempted      = { 0x31, 0xc0 },       // xor %eax, %eax
  62
  63 # ifdef CONFIG_X86_64
  64         .queued_spin_unlock     = { 0xc6, 0x07, 0x00 }, // movb $0, (%rdi)
  65 # else
  66         .queued_spin_unlock     = { 0xc6, 0x00, 0x00 }, // movb $0, (%eax)
  67 # endif
  68 };
  69 #endif /* CONFIG_PARAVIRT_SPINLOCKS */
  70
  71 unsigned int native_patch(u8 type, void *insn_buff, unsigned long addr,
  72                           unsigned int len)
  73 {
  74         switch (type) {
  75
  76 #ifdef CONFIG_PARAVIRT_XXL
  77         PATCH_CASE(irq, restore_fl, xxl, insn_buff, len);
  78         PATCH_CASE(irq, save_fl, xxl, insn_buff, len);
  79         PATCH_CASE(irq, irq_enable, xxl, insn_buff, len);
  80         PATCH_CASE(irq, irq_disable, xxl, insn_buff, len);
  81
  82         PATCH_CASE(mmu, read_cr2, xxl, insn_buff, len);
  83         PATCH_CASE(mmu, read_cr3, xxl, insn_buff, len);
  84         PATCH_CASE(mmu, write_cr3, xxl, insn_buff, len);
  85
  86         PATCH_CASE(cpu, usergs_sysret64, xxl, insn_buff, len);
  87         PATCH_CASE(cpu, wbinvd, xxl, insn_buff, len);
  88 #endif
  89
  90 #ifdef CONFIG_PARAVIRT_SPINLOCKS
  91         case PARAVIRT_PATCH(lock.queued_spin_unlock):
  92                 if (pv_is_native_spin_unlock())
  93                         return PATCH(lock, queued_spin_unlock, insn_buff, len);
  94                 break;
  95
  96         case PARAVIRT_PATCH(lock.vcpu_is_preempted):
  97                 if (pv_is_native_vcpu_is_preempted())
  98                         return PATCH(lock, vcpu_is_preempted, insn_buff, len);
  99                 break;
 100 #endif
 101         default:
 102                 break;
 103         }
 104
 105         return paravirt_patch_default(type, insn_buff, addr, len);
 106 }