tools/testing/selftests/x86/pkey-helpers.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _PKEYS_HELPER_H
   3 #define _PKEYS_HELPER_H
   4 #define _GNU_SOURCE
   5 #include <string.h>
   6 #include <stdarg.h>
   7 #include <stdio.h>
   8 #include <stdint.h>
   9 #include <stdbool.h>
  10 #include <signal.h>
  11 #include <assert.h>
  12 #include <stdlib.h>
  13 #include <ucontext.h>
  14 #include <sys/mman.h>
  15
  16 #define NR_PKEYS 16
  17 #define PKRU_BITS_PER_PKEY 2
  18
  19 #ifndef DEBUG_LEVEL
  20 #define DEBUG_LEVEL 0
  21 #endif
  22 #define DPRINT_IN_SIGNAL_BUF_SIZE 4096
  23 extern int dprint_in_signal;
  24 extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
  25 static inline void sigsafe_printf(const char *format, ...)
  26 {
  27         va_list ap;
  28
  29         va_start(ap, format);
  30         if (!dprint_in_signal) {
  31                 vprintf(format, ap);
  32         } else {
  33                 int len = vsnprintf(dprint_in_signal_buffer,
  34                                     DPRINT_IN_SIGNAL_BUF_SIZE,
  35                                     format, ap);
  36                 /*
  37                  * len is amount that would have been printed,
  38                  * but actual write is truncated at BUF_SIZE.
  39                  */
  40                 if (len > DPRINT_IN_SIGNAL_BUF_SIZE)
  41                         len = DPRINT_IN_SIGNAL_BUF_SIZE;
  42                 write(1, dprint_in_signal_buffer, len);
  43         }
  44         va_end(ap);
  45 }
  46 #define dprintf_level(level, args...) do {      \
  47         if (level <= DEBUG_LEVEL)               \
  48                 sigsafe_printf(args);           \
  49         fflush(NULL);                           \
  50 } while (0)
  51 #define dprintf0(args...) dprintf_level(0, args)
  52 #define dprintf1(args...) dprintf_level(1, args)
  53 #define dprintf2(args...) dprintf_level(2, args)
  54 #define dprintf3(args...) dprintf_level(3, args)
  55 #define dprintf4(args...) dprintf_level(4, args)
  56
  57 extern unsigned int shadow_pkru;
  58 static inline unsigned int __rdpkru(void)
  59 {
  60         unsigned int eax, edx;
  61         unsigned int ecx = 0;
  62         unsigned int pkru;
  63
  64         asm volatile(".byte 0x0f,0x01,0xee\n\t"
  65                      : "=a" (eax), "=d" (edx)
  66                      : "c" (ecx));
  67         pkru = eax;
  68         return pkru;
  69 }
  70
  71 static inline unsigned int _rdpkru(int line)
  72 {
  73         unsigned int pkru = __rdpkru();
  74
  75         dprintf4("rdpkru(line=%d) pkru: %x shadow: %x\n",
  76                         line, pkru, shadow_pkru);
  77         assert(pkru == shadow_pkru);
  78
  79         return pkru;
  80 }
  81
  82 #define rdpkru() _rdpkru(__LINE__)
  83
  84 static inline void __wrpkru(unsigned int pkru)
  85 {
  86         unsigned int eax = pkru;
  87         unsigned int ecx = 0;
  88         unsigned int edx = 0;
  89
  90         dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
  91         asm volatile(".byte 0x0f,0x01,0xef\n\t"
  92                      : : "a" (eax), "c" (ecx), "d" (edx));
  93         assert(pkru == __rdpkru());
  94 }
  95
  96 static inline void wrpkru(unsigned int pkru)
  97 {
  98         dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
  99         /* will do the shadow check for us: */
 100         rdpkru();
 101         __wrpkru(pkru);
 102         shadow_pkru = pkru;
 103         dprintf4("%s(%08x) pkru: %08x\n", __func__, pkru, __rdpkru());
 104 }
 105
 106 /*
 107  * These are technically racy. since something could
 108  * change PKRU between the read and the write.
 109  */
 110 static inline void __pkey_access_allow(int pkey, int do_allow)
 111 {
 112         unsigned int pkru = rdpkru();
 113         int bit = pkey * 2;
 114
 115         if (do_allow)
 116                 pkru &= (1<<bit);
 117         else
 118                 pkru |= (1<<bit);
 119
 120         dprintf4("pkru now: %08x\n", rdpkru());
 121         wrpkru(pkru);
 122 }
 123
 124 static inline void __pkey_write_allow(int pkey, int do_allow_write)
 125 {
 126         long pkru = rdpkru();
 127         int bit = pkey * 2 + 1;
 128
 129         if (do_allow_write)
 130                 pkru &= (1<<bit);
 131         else
 132                 pkru |= (1<<bit);
 133
 134         wrpkru(pkru);
 135         dprintf4("pkru now: %08x\n", rdpkru());
 136 }
 137
 138 #define PROT_PKEY0     0x10            /* protection key value (bit 0) */
 139 #define PROT_PKEY1     0x20            /* protection key value (bit 1) */
 140 #define PROT_PKEY2     0x40            /* protection key value (bit 2) */
 141 #define PROT_PKEY3     0x80            /* protection key value (bit 3) */
 142
 143 #define PAGE_SIZE 4096
 144 #define MB      (1<<20)
 145
 146 static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
 147                 unsigned int *ecx, unsigned int *edx)
 148 {
 149         /* ecx is often an input as well as an output. */
 150         asm volatile(
 151                 "cpuid;"
 152                 : "=a" (*eax),
 153                   "=b" (*ebx),
 154                   "=c" (*ecx),
 155                   "=d" (*edx)
 156                 : "0" (*eax), "2" (*ecx));
 157 }
 158
 159 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
 160 #define X86_FEATURE_PKU        (1<<3) /* Protection Keys for Userspace */
 161 #define X86_FEATURE_OSPKE      (1<<4) /* OS Protection Keys Enable */
 162
 163 static inline int cpu_has_pku(void)
 164 {
 165         unsigned int eax;
 166         unsigned int ebx;
 167         unsigned int ecx;
 168         unsigned int edx;
 169
 170         eax = 0x7;
 171         ecx = 0x0;
 172         __cpuid(&eax, &ebx, &ecx, &edx);
 173
 174         if (!(ecx & X86_FEATURE_PKU)) {
 175                 dprintf2("cpu does not have PKU\n");
 176                 return 0;
 177         }
 178         if (!(ecx & X86_FEATURE_OSPKE)) {
 179                 dprintf2("cpu does not have OSPKE\n");
 180                 return 0;
 181         }
 182         return 1;
 183 }
 184
 185 #define XSTATE_PKRU_BIT (9)
 186 #define XSTATE_PKRU     0x200
 187
 188 int pkru_xstate_offset(void)
 189 {
 190         unsigned int eax;
 191         unsigned int ebx;
 192         unsigned int ecx;
 193         unsigned int edx;
 194         int xstate_offset;
 195         int xstate_size;
 196         unsigned long XSTATE_CPUID = 0xd;
 197         int leaf;
 198
 199         /* assume that XSTATE_PKRU is set in XCR0 */
 200         leaf = XSTATE_PKRU_BIT;
 201         {
 202                 eax = XSTATE_CPUID;
 203                 ecx = leaf;
 204                 __cpuid(&eax, &ebx, &ecx, &edx);
 205
 206                 if (leaf == XSTATE_PKRU_BIT) {
 207                         xstate_offset = ebx;
 208                         xstate_size = eax;
 209                 }
 210         }
 211
 212         if (xstate_size == 0) {
 213                 printf("could not find size/offset of PKRU in xsave state\n");
 214                 return 0;
 215         }
 216
 217         return xstate_offset;
 218 }
 219
 220 #endif /* _PKEYS_HELPER_H */