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/irqflags.h>
11 #include <linux/jump_label.h>
12 
13 /*
14  * The compiler should not reorder volatile asm statements with respect to each
15  * other: they should execute in program order. However GCC 4.9.x and 5.x have
16  * a bug (which was fixed in 8.1, 7.3 and 6.5) where they might reorder
17  * volatile asm. The write functions are not affected since they have memory
18  * clobbers preventing reordering. To prevent reads from being reordered with
19  * respect to writes, use a dummy memory operand.
20  */
21 
22 #define __FORCE_ORDER "m"(*(unsigned int *)0x1000UL)
23 
24 void native_write_cr0(unsigned long val);
25 
26 static inline unsigned long native_read_cr0(void)
27 {
28 	unsigned long val;
29 	asm volatile("mov %%cr0,%0\n\t" : "=r" (val) : __FORCE_ORDER);
30 	return val;
31 }
32 
33 static __always_inline unsigned long native_read_cr2(void)
34 {
35 	unsigned long val;
36 	asm volatile("mov %%cr2,%0\n\t" : "=r" (val) : __FORCE_ORDER);
37 	return val;
38 }
39 
40 static __always_inline void native_write_cr2(unsigned long val)
41 {
42 	asm volatile("mov %0,%%cr2": : "r" (val) : "memory");
43 }
44 
45 static inline unsigned long __native_read_cr3(void)
46 {
47 	unsigned long val;
48 	asm volatile("mov %%cr3,%0\n\t" : "=r" (val) : __FORCE_ORDER);
49 	return val;
50 }
51 
52 static inline void native_write_cr3(unsigned long val)
53 {
54 	asm volatile("mov %0,%%cr3": : "r" (val) : "memory");
55 }
56 
57 static inline unsigned long native_read_cr4(void)
58 {
59 	unsigned long val;
60 #ifdef CONFIG_X86_32
61 	/*
62 	 * This could fault if CR4 does not exist.  Non-existent CR4
63 	 * is functionally equivalent to CR4 == 0.  Keep it simple and pretend
64 	 * that CR4 == 0 on CPUs that don't have CR4.
65 	 */
66 	asm volatile("1: mov %%cr4, %0\n"
67 		     "2:\n"
68 		     _ASM_EXTABLE(1b, 2b)
69 		     : "=r" (val) : "0" (0), __FORCE_ORDER);
70 #else
71 	/* CR4 always exists on x86_64. */
72 	asm volatile("mov %%cr4,%0\n\t" : "=r" (val) : __FORCE_ORDER);
73 #endif
74 	return val;
75 }
76 
77 void native_write_cr4(unsigned long val);
78 
79 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
80 static inline u32 rdpkru(void)
81 {
82 	u32 ecx = 0;
83 	u32 edx, pkru;
84 
85 	/*
86 	 * "rdpkru" instruction.  Places PKRU contents in to EAX,
87 	 * clears EDX and requires that ecx=0.
88 	 */
89 	asm volatile(".byte 0x0f,0x01,0xee\n\t"
90 		     : "=a" (pkru), "=d" (edx)
91 		     : "c" (ecx));
92 	return pkru;
93 }
94 
95 static inline void wrpkru(u32 pkru)
96 {
97 	u32 ecx = 0, edx = 0;
98 
99 	/*
100 	 * "wrpkru" instruction.  Loads contents in EAX to PKRU,
101 	 * requires that ecx = edx = 0.
102 	 */
103 	asm volatile(".byte 0x0f,0x01,0xef\n\t"
104 		     : : "a" (pkru), "c"(ecx), "d"(edx));
105 }
106 
107 static inline void __write_pkru(u32 pkru)
108 {
109 	/*
110 	 * WRPKRU is relatively expensive compared to RDPKRU.
111 	 * Avoid WRPKRU when it would not change the value.
112 	 */
113 	if (pkru == rdpkru())
114 		return;
115 
116 	wrpkru(pkru);
117 }
118 
119 #else
120 static inline u32 rdpkru(void)
121 {
122 	return 0;
123 }
124 
125 static inline void __write_pkru(u32 pkru)
126 {
127 }
128 #endif
129 
130 static inline void native_wbinvd(void)
131 {
132 	asm volatile("wbinvd": : :"memory");
133 }
134 
135 extern asmlinkage void asm_load_gs_index(unsigned int selector);
136 
137 static inline void native_load_gs_index(unsigned int selector)
138 {
139 	unsigned long flags;
140 
141 	local_irq_save(flags);
142 	asm_load_gs_index(selector);
143 	local_irq_restore(flags);
144 }
145 
146 static inline unsigned long __read_cr4(void)
147 {
148 	return native_read_cr4();
149 }
150 
151 #ifdef CONFIG_PARAVIRT_XXL
152 #include <asm/paravirt.h>
153 #else
154 
155 static inline unsigned long read_cr0(void)
156 {
157 	return native_read_cr0();
158 }
159 
160 static inline void write_cr0(unsigned long x)
161 {
162 	native_write_cr0(x);
163 }
164 
165 static __always_inline unsigned long read_cr2(void)
166 {
167 	return native_read_cr2();
168 }
169 
170 static __always_inline void write_cr2(unsigned long x)
171 {
172 	native_write_cr2(x);
173 }
174 
175 /*
176  * Careful!  CR3 contains more than just an address.  You probably want
177  * read_cr3_pa() instead.
178  */
179 static inline unsigned long __read_cr3(void)
180 {
181 	return __native_read_cr3();
182 }
183 
184 static inline void write_cr3(unsigned long x)
185 {
186 	native_write_cr3(x);
187 }
188 
189 static inline void __write_cr4(unsigned long x)
190 {
191 	native_write_cr4(x);
192 }
193 
194 static inline void wbinvd(void)
195 {
196 	native_wbinvd();
197 }
198 
199 #ifdef CONFIG_X86_64
200 
201 static inline void load_gs_index(unsigned int selector)
202 {
203 	native_load_gs_index(selector);
204 }
205 
206 #endif
207 
208 #endif /* CONFIG_PARAVIRT_XXL */
209 
210 static inline void clflush(volatile void *__p)
211 {
212 	asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
213 }
214 
215 static inline void clflushopt(volatile void *__p)
216 {
217 	alternative_io(".byte 0x3e; clflush %P0",
218 		       ".byte 0x66; clflush %P0",
219 		       X86_FEATURE_CLFLUSHOPT,
220 		       "+m" (*(volatile char __force *)__p));
221 }
222 
223 static inline void clwb(volatile void *__p)
224 {
225 	volatile struct { char x[64]; } *p = __p;
226 
227 	asm volatile(ALTERNATIVE_2(
228 		".byte 0x3e; clflush (%[pax])",
229 		".byte 0x66; clflush (%[pax])", /* clflushopt (%%rax) */
230 		X86_FEATURE_CLFLUSHOPT,
231 		".byte 0x66, 0x0f, 0xae, 0x30",  /* clwb (%%rax) */
232 		X86_FEATURE_CLWB)
233 		: [p] "+m" (*p)
234 		: [pax] "a" (p));
235 }
236 
237 #define nop() asm volatile ("nop")
238 
239 static inline void serialize(void)
240 {
241 	/* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
242 	asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");
243 }
244 
245 /* The dst parameter must be 64-bytes aligned */
246 static inline void movdir64b(void __iomem *dst, const void *src)
247 {
248 	const struct { char _[64]; } *__src = src;
249 	struct { char _[64]; } __iomem *__dst = dst;
250 
251 	/*
252 	 * MOVDIR64B %(rdx), rax.
253 	 *
254 	 * Both __src and __dst must be memory constraints in order to tell the
255 	 * compiler that no other memory accesses should be reordered around
256 	 * this one.
257 	 *
258 	 * Also, both must be supplied as lvalues because this tells
259 	 * the compiler what the object is (its size) the instruction accesses.
260 	 * I.e., not the pointers but what they point to, thus the deref'ing '*'.
261 	 */
262 	asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
263 		     : "+m" (*__dst)
264 		     :  "m" (*__src), "a" (__dst), "d" (__src));
265 }
266 
267 /**
268  * enqcmds - Enqueue a command in supervisor (CPL0) mode
269  * @dst: destination, in MMIO space (must be 512-bit aligned)
270  * @src: 512 bits memory operand
271  *
272  * The ENQCMDS instruction allows software to write a 512-bit command to
273  * a 512-bit-aligned special MMIO region that supports the instruction.
274  * A return status is loaded into the ZF flag in the RFLAGS register.
275  * ZF = 0 equates to success, and ZF = 1 indicates retry or error.
276  *
277  * This function issues the ENQCMDS instruction to submit data from
278  * kernel space to MMIO space, in a unit of 512 bits. Order of data access
279  * is not guaranteed, nor is a memory barrier performed afterwards. It
280  * returns 0 on success and -EAGAIN on failure.
281  *
282  * Warning: Do not use this helper unless your driver has checked that the
283  * ENQCMDS instruction is supported on the platform and the device accepts
284  * ENQCMDS.
285  */
286 static inline int enqcmds(void __iomem *dst, const void *src)
287 {
288 	const struct { char _[64]; } *__src = src;
289 	struct { char _[64]; } __iomem *__dst = dst;
290 	int zf;
291 
292 	/*
293 	 * ENQCMDS %(rdx), rax
294 	 *
295 	 * See movdir64b()'s comment on operand specification.
296 	 */
297 	asm volatile(".byte 0xf3, 0x0f, 0x38, 0xf8, 0x02, 0x66, 0x90"
298 		     CC_SET(z)
299 		     : CC_OUT(z) (zf), "+m" (*__dst)
300 		     : "m" (*__src), "a" (__dst), "d" (__src));
301 
302 	/* Submission failure is indicated via EFLAGS.ZF=1 */
303 	if (zf)
304 		return -EAGAIN;
305 
306 	return 0;
307 }
308 
309 #endif /* __KERNEL__ */
310 
311 #endif /* _ASM_X86_SPECIAL_INSNS_H */
312