arch/x86/include/asm/special_insns.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_SPECIAL_INSNS_H
   3 #define _ASM_X86_SPECIAL_INSNS_H
   4
   5
   6 #ifdef __KERNEL__
   7
   8 #include <asm/nops.h>
   9 #include <asm/processor-flags.h>
  10 #include <linux/jump_label.h>
  11
  12 /*
  13  * Volatile isn't enough to prevent the compiler from reordering the
  14  * read/write functions for the control registers and messing everything up.
  15  * A memory clobber would solve the problem, but would prevent reordering of
  16  * all loads stores around it, which can hurt performance. Solution is to
  17  * use a variable and mimic reads and writes to it to enforce serialization
  18  */
  19 extern unsigned long __force_order;
  20
  21 void native_write_cr0(unsigned long val);
  22
  23 static inline unsigned long native_read_cr0(void)
  24 {
  25         unsigned long val;
  26         asm volatile("mov %%cr0,%0\n\t" : "=r" (val), "=m" (__force_order));
  27         return val;
  28 }
  29
  30 static inline unsigned long native_read_cr2(void)
  31 {
  32         unsigned long val;
  33         asm volatile("mov %%cr2,%0\n\t" : "=r" (val), "=m" (__force_order));
  34         return val;
  35 }
  36
  37 static inline void native_write_cr2(unsigned long val)
  38 {
  39         asm volatile("mov %0,%%cr2": : "r" (val), "m" (__force_order));
  40 }
  41
  42 static inline unsigned long __native_read_cr3(void)
  43 {
  44         unsigned long val;
  45         asm volatile("mov %%cr3,%0\n\t" : "=r" (val), "=m" (__force_order));
  46         return val;
  47 }
  48
  49 static inline void native_write_cr3(unsigned long val)
  50 {
  51         asm volatile("mov %0,%%cr3": : "r" (val), "m" (__force_order));
  52 }
  53
  54 static inline unsigned long native_read_cr4(void)
  55 {
  56         unsigned long val;
  57 #ifdef CONFIG_X86_32
  58         /*
  59          * This could fault if CR4 does not exist.  Non-existent CR4
  60          * is functionally equivalent to CR4 == 0.  Keep it simple and pretend
  61          * that CR4 == 0 on CPUs that don't have CR4.
  62          */
  63         asm volatile("1: mov %%cr4, %0\n"
  64                      "2:\n"
  65                      _ASM_EXTABLE(1b, 2b)
  66                      : "=r" (val), "=m" (__force_order) : "0" (0));
  67 #else
  68         /* CR4 always exists on x86_64. */
  69         asm volatile("mov %%cr4,%0\n\t" : "=r" (val), "=m" (__force_order));
  70 #endif
  71         return val;
  72 }
  73
  74 void native_write_cr4(unsigned long val);
  75
  76 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
  77 static inline u32 rdpkru(void)
  78 {
  79         u32 ecx = 0;
  80         u32 edx, pkru;
  81
  82         /*
  83          * "rdpkru" instruction.  Places PKRU contents in to EAX,
  84          * clears EDX and requires that ecx=0.
  85          */
  86         asm volatile(".byte 0x0f,0x01,0xee\n\t"
  87                      : "=a" (pkru), "=d" (edx)
  88                      : "c" (ecx));
  89         return pkru;
  90 }
  91
  92 static inline void wrpkru(u32 pkru)
  93 {
  94         u32 ecx = 0, edx = 0;
  95
  96         /*
  97          * "wrpkru" instruction.  Loads contents in EAX to PKRU,
  98          * requires that ecx = edx = 0.
  99          */
 100         asm volatile(".byte 0x0f,0x01,0xef\n\t"
 101                      : : "a" (pkru), "c"(ecx), "d"(edx));
 102 }
 103
 104 static inline void __write_pkru(u32 pkru)
 105 {
 106         /*
 107          * WRPKRU is relatively expensive compared to RDPKRU.
 108          * Avoid WRPKRU when it would not change the value.
 109          */
 110         if (pkru == rdpkru())
 111                 return;
 112
 113         wrpkru(pkru);
 114 }
 115
 116 #else
 117 static inline u32 rdpkru(void)
 118 {
 119         return 0;
 120 }
 121
 122 static inline void __write_pkru(u32 pkru)
 123 {
 124 }
 125 #endif
 126
 127 static inline void native_wbinvd(void)
 128 {
 129         asm volatile("wbinvd": : :"memory");
 130 }
 131
 132 extern asmlinkage void native_load_gs_index(unsigned);
 133
 134 static inline unsigned long __read_cr4(void)
 135 {
 136         return native_read_cr4();
 137 }
 138
 139 #ifdef CONFIG_PARAVIRT_XXL
 140 #include <asm/paravirt.h>
 141 #else
 142
 143 static inline unsigned long read_cr0(void)
 144 {
 145         return native_read_cr0();
 146 }
 147
 148 static inline void write_cr0(unsigned long x)
 149 {
 150         native_write_cr0(x);
 151 }
 152
 153 static inline unsigned long read_cr2(void)
 154 {
 155         return native_read_cr2();
 156 }
 157
 158 static inline void write_cr2(unsigned long x)
 159 {
 160         native_write_cr2(x);
 161 }
 162
 163 /*
 164  * Careful!  CR3 contains more than just an address.  You probably want
 165  * read_cr3_pa() instead.
 166  */
 167 static inline unsigned long __read_cr3(void)
 168 {
 169         return __native_read_cr3();
 170 }
 171
 172 static inline void write_cr3(unsigned long x)
 173 {
 174         native_write_cr3(x);
 175 }
 176
 177 static inline void __write_cr4(unsigned long x)
 178 {
 179         native_write_cr4(x);
 180 }
 181
 182 static inline void wbinvd(void)
 183 {
 184         native_wbinvd();
 185 }
 186
 187 #ifdef CONFIG_X86_64
 188
 189 static inline void load_gs_index(unsigned selector)
 190 {
 191         native_load_gs_index(selector);
 192 }
 193
 194 #endif
 195
 196 #endif /* CONFIG_PARAVIRT_XXL */
 197
 198 static inline void clflush(volatile void *__p)
 199 {
 200         asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
 201 }
 202
 203 static inline void clflushopt(volatile void *__p)
 204 {
 205         alternative_io(".byte " __stringify(NOP_DS_PREFIX) "; clflush %P0",
 206                        ".byte 0x66; clflush %P0",
 207                        X86_FEATURE_CLFLUSHOPT,
 208                        "+m" (*(volatile char __force *)__p));
 209 }
 210
 211 static inline void clwb(volatile void *__p)
 212 {
 213         volatile struct { char x[64]; } *p = __p;
 214
 215         asm volatile(ALTERNATIVE_2(
 216                 ".byte " __stringify(NOP_DS_PREFIX) "; clflush (%[pax])",
 217                 ".byte 0x66; clflush (%[pax])", /* clflushopt (%%rax) */
 218                 X86_FEATURE_CLFLUSHOPT,
 219                 ".byte 0x66, 0x0f, 0xae, 0x30",  /* clwb (%%rax) */
 220                 X86_FEATURE_CLWB)
 221                 : [p] "+m" (*p)
 222                 : [pax] "a" (p));
 223 }
 224
 225 #define nop() asm volatile ("nop")
 226
 227
 228 #endif /* __KERNEL__ */
 229
 230 #endif /* _ASM_X86_SPECIAL_INSNS_H */