arch/x86/include/asm/pkru.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_PKRU_H
   3 #define _ASM_X86_PKRU_H
   4
   5 #include <asm/fpu/xstate.h>
   6
   7 #define PKRU_AD_BIT 0x1
   8 #define PKRU_WD_BIT 0x2
   9 #define PKRU_BITS_PER_PKEY 2
  10
  11 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
  12 extern u32 init_pkru_value;
  13 #else
  14 #define init_pkru_value 0
  15 #endif
  16
  17 static inline bool __pkru_allows_read(u32 pkru, u16 pkey)
  18 {
  19         int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
  20         return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits));
  21 }
  22
  23 static inline bool __pkru_allows_write(u32 pkru, u16 pkey)
  24 {
  25         int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
  26         /*
  27          * Access-disable disables writes too so we need to check
  28          * both bits here.
  29          */
  30         return !(pkru & ((PKRU_AD_BIT|PKRU_WD_BIT) << pkru_pkey_bits));
  31 }
  32
  33 static inline u32 read_pkru(void)
  34 {
  35         if (boot_cpu_has(X86_FEATURE_OSPKE))
  36                 return rdpkru();
  37         return 0;
  38 }
  39
  40 static inline void write_pkru(u32 pkru)
  41 {
  42         struct pkru_state *pk;
  43
  44         if (!boot_cpu_has(X86_FEATURE_OSPKE))
  45                 return;
  46
  47         pk = get_xsave_addr(&current->thread.fpu.state.xsave, XFEATURE_PKRU);
  48
  49         /*
  50          * The PKRU value in xstate needs to be in sync with the value that is
  51          * written to the CPU. The FPU restore on return to userland would
  52          * otherwise load the previous value again.
  53          */
  54         fpregs_lock();
  55         if (pk)
  56                 pk->pkru = pkru;
  57         __write_pkru(pkru);
  58         fpregs_unlock();
  59 }
  60
  61 #endif