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

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  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         if (!dprint_in_signal) {
 30                 va_start(ap, format);
 31                 vprintf(format, ap);
 32                 va_end(ap);
 33         } else {
 34                 int ret;
 35                 /*
 36                  * No printf() functions are signal-safe.
 37                  * They deadlock easily. Write the format
 38                  * string to get some output, even if
 39                  * incomplete.
 40                  */
 41                 ret = write(1, format, strlen(format));
 42                 if (ret < 0)
 43                         exit(1);
 44         }
 45 }
 46 #define dprintf_level(level, args...) do {      \
 47         if (level <= DEBUG_LEVEL)               \
 48                 sigsafe_printf(args);           \
 49 } while (0)
 50 #define dprintf0(args...) dprintf_level(0, args)
 51 #define dprintf1(args...) dprintf_level(1, args)
 52 #define dprintf2(args...) dprintf_level(2, args)
 53 #define dprintf3(args...) dprintf_level(3, args)
 54 #define dprintf4(args...) dprintf_level(4, args)
 55 
 56 extern unsigned int shadow_pkru;
 57 static inline unsigned int __rdpkru(void)
 58 {
 59         unsigned int eax, edx;
 60         unsigned int ecx = 0;
 61         unsigned int pkru;
 62 
 63         asm volatile(".byte 0x0f,0x01,0xee\n\t"
 64                      : "=a" (eax), "=d" (edx)
 65                      : "c" (ecx));
 66         pkru = eax;
 67         return pkru;
 68 }
 69 
 70 static inline unsigned int _rdpkru(int line)
 71 {
 72         unsigned int pkru = __rdpkru();
 73 
 74         dprintf4("rdpkru(line=%d) pkru: %x shadow: %x\n",
 75                         line, pkru, shadow_pkru);
 76         assert(pkru == shadow_pkru);
 77 
 78         return pkru;
 79 }
 80 
 81 #define rdpkru() _rdpkru(__LINE__)
 82 
 83 static inline void __wrpkru(unsigned int pkru)
 84 {
 85         unsigned int eax = pkru;
 86         unsigned int ecx = 0;
 87         unsigned int edx = 0;
 88 
 89         dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
 90         asm volatile(".byte 0x0f,0x01,0xef\n\t"
 91                      : : "a" (eax), "c" (ecx), "d" (edx));
 92         assert(pkru == __rdpkru());
 93 }
 94 
 95 static inline void wrpkru(unsigned int pkru)
 96 {
 97         dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
 98         /* will do the shadow check for us: */
 99         rdpkru();
100         __wrpkru(pkru);
101         shadow_pkru = pkru;
102         dprintf4("%s(%08x) pkru: %08x\n", __func__, pkru, __rdpkru());
103 }
104 
105 /*
106  * These are technically racy. since something could
107  * change PKRU between the read and the write.
108  */
109 static inline void __pkey_access_allow(int pkey, int do_allow)
110 {
111         unsigned int pkru = rdpkru();
112         int bit = pkey * 2;
113 
114         if (do_allow)
115                 pkru &= (1<<bit);
116         else
117                 pkru |= (1<<bit);
118 
119         dprintf4("pkru now: %08x\n", rdpkru());
120         wrpkru(pkru);
121 }
122 
123 static inline void __pkey_write_allow(int pkey, int do_allow_write)
124 {
125         long pkru = rdpkru();
126         int bit = pkey * 2 + 1;
127 
128         if (do_allow_write)
129                 pkru &= (1<<bit);
130         else
131                 pkru |= (1<<bit);
132 
133         wrpkru(pkru);
134         dprintf4("pkru now: %08x\n", rdpkru());
135 }
136 
137 #define PROT_PKEY0     0x10            /* protection key value (bit 0) */
138 #define PROT_PKEY1     0x20            /* protection key value (bit 1) */
139 #define PROT_PKEY2     0x40            /* protection key value (bit 2) */
140 #define PROT_PKEY3     0x80            /* protection key value (bit 3) */
141 
142 #define PAGE_SIZE 4096
143 #define MB      (1<<20)
144 
145 static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
146                 unsigned int *ecx, unsigned int *edx)
147 {
148         /* ecx is often an input as well as an output. */
149         asm volatile(
150                 "cpuid;"
151                 : "=a" (*eax),
152                   "=b" (*ebx),
153                   "=c" (*ecx),
154                   "=d" (*edx)
155                 : "" (*eax), "2" (*ecx));
156 }
157 
158 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
159 #define X86_FEATURE_PKU        (1<<3) /* Protection Keys for Userspace */
160 #define X86_FEATURE_OSPKE      (1<<4) /* OS Protection Keys Enable */
161 
162 static inline int cpu_has_pku(void)
163 {
164         unsigned int eax;
165         unsigned int ebx;
166         unsigned int ecx;
167         unsigned int edx;
168 
169         eax = 0x7;
170         ecx = 0x0;
171         __cpuid(&eax, &ebx, &ecx, &edx);
172 
173         if (!(ecx & X86_FEATURE_PKU)) {
174                 dprintf2("cpu does not have PKU\n");
175                 return 0;
176         }
177         if (!(ecx & X86_FEATURE_OSPKE)) {
178                 dprintf2("cpu does not have OSPKE\n");
179                 return 0;
180         }
181         return 1;
182 }
183 
184 #define XSTATE_PKRU_BIT (9)
185 #define XSTATE_PKRU     0x200
186 
187 int pkru_xstate_offset(void)
188 {
189         unsigned int eax;
190         unsigned int ebx;
191         unsigned int ecx;
192         unsigned int edx;
193         int xstate_offset;
194         int xstate_size;
195         unsigned long XSTATE_CPUID = 0xd;
196         int leaf;
197 
198         /* assume that XSTATE_PKRU is set in XCR0 */
199         leaf = XSTATE_PKRU_BIT;
200         {
201                 eax = XSTATE_CPUID;
202                 ecx = leaf;
203                 __cpuid(&eax, &ebx, &ecx, &edx);
204 
205                 if (leaf == XSTATE_PKRU_BIT) {
206                         xstate_offset = ebx;
207                         xstate_size = eax;
208                 }
209         }
210 
211         if (xstate_size == 0) {
212                 printf("could not find size/offset of PKRU in xsave state\n");
213                 return 0;
214         }
215 
216         return xstate_offset;
217 }
218 
219 #endif /* _PKEYS_HELPER_H */
220 

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