tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _PKEYS_HELPER_H
2#define _PKEYS_HELPER_H
3#define _GNU_SOURCE
4#include <string.h>
5#include <stdarg.h>
6#include <stdio.h>
7#include <stdint.h>
8#include <stdbool.h>
9#include <signal.h>
10#include <assert.h>
11#include <stdlib.h>
12#include <ucontext.h>
13#include <sys/mman.h>
14
15#define NR_PKEYS 16
16#define PKRU_BITS_PER_PKEY 2
17
18#ifndef DEBUG_LEVEL
19#define DEBUG_LEVEL 0
20#endif
21#define DPRINT_IN_SIGNAL_BUF_SIZE 4096
22extern int dprint_in_signal;
23extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
24static inline void sigsafe_printf(const char *format, ...)
25{
26 va_list ap;
27
28 va_start(ap, format);
29 if (!dprint_in_signal) {
30 vprintf(format, ap);
31 } else {
32 int len = vsnprintf(dprint_in_signal_buffer,
33 DPRINT_IN_SIGNAL_BUF_SIZE,
34 format, ap);
35 /*
36 * len is amount that would have been printed,
37 * but actual write is truncated at BUF_SIZE.
38 */
39 if (len > DPRINT_IN_SIGNAL_BUF_SIZE)
40 len = DPRINT_IN_SIGNAL_BUF_SIZE;
41 write(1, dprint_in_signal_buffer, len);
42 }
43 va_end(ap);
44}
45#define dprintf_level(level, args...) do { \
46 if (level <= DEBUG_LEVEL) \
47 sigsafe_printf(args); \
48 fflush(NULL); \
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
56extern unsigned int shadow_pkru;
57static 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
70static 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
83static 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
95static 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 */
109static 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
123static 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
145static 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 : "0" (*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
162static 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
187int 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 */