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 
native_read_cr0(void)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 
native_read_cr2(void)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 
native_write_cr2(unsigned long val)40 static __always_inline void native_write_cr2(unsigned long val)
41 {
42 	asm volatile("mov %0,%%cr2": : "r" (val) : "memory");
43 }
44 
__native_read_cr3(void)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 
native_write_cr3(unsigned long val)52 static inline void native_write_cr3(unsigned long val)
53 {
54 	asm volatile("mov %0,%%cr3": : "r" (val) : "memory");
55 }
56 
native_read_cr4(void)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
rdpkru(void)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 
wrpkru(u32 pkru)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 #else
rdpkru(void)108 static inline u32 rdpkru(void)
109 {
110 	return 0;
111 }
112 
wrpkru(u32 pkru)113 static inline void wrpkru(u32 pkru)
114 {
115 }
116 #endif
117 
native_wbinvd(void)118 static inline void native_wbinvd(void)
119 {
120 	asm volatile("wbinvd": : :"memory");
121 }
122 
123 extern asmlinkage void asm_load_gs_index(unsigned int selector);
124 
native_load_gs_index(unsigned int selector)125 static inline void native_load_gs_index(unsigned int selector)
126 {
127 	unsigned long flags;
128 
129 	local_irq_save(flags);
130 	asm_load_gs_index(selector);
131 	local_irq_restore(flags);
132 }
133 
__read_cr4(void)134 static inline unsigned long __read_cr4(void)
135 {
136 	return native_read_cr4();
137 }
138 
139 #ifdef CONFIG_PARAVIRT_XXL
140 #include <asm/paravirt.h>
141 #else
142 
read_cr0(void)143 static inline unsigned long read_cr0(void)
144 {
145 	return native_read_cr0();
146 }
147 
write_cr0(unsigned long x)148 static inline void write_cr0(unsigned long x)
149 {
150 	native_write_cr0(x);
151 }
152 
read_cr2(void)153 static __always_inline unsigned long read_cr2(void)
154 {
155 	return native_read_cr2();
156 }
157 
write_cr2(unsigned long x)158 static __always_inline void write_cr2(unsigned long x)
159 {
160 	native_write_cr2(x);
161 }
162 
163 /*
164  * Careful!  CR3 contains more than just an address.  You probably want
165  * read_cr3_pa() instead.
166  */
__read_cr3(void)167 static inline unsigned long __read_cr3(void)
168 {
169 	return __native_read_cr3();
170 }
171 
write_cr3(unsigned long x)172 static inline void write_cr3(unsigned long x)
173 {
174 	native_write_cr3(x);
175 }
176 
__write_cr4(unsigned long x)177 static inline void __write_cr4(unsigned long x)
178 {
179 	native_write_cr4(x);
180 }
181 
wbinvd(void)182 static inline void wbinvd(void)
183 {
184 	native_wbinvd();
185 }
186 
187 #ifdef CONFIG_X86_64
188 
load_gs_index(unsigned int selector)189 static inline void load_gs_index(unsigned int selector)
190 {
191 	native_load_gs_index(selector);
192 }
193 
194 #endif
195 
196 #endif /* CONFIG_PARAVIRT_XXL */
197 
clflush(volatile void * __p)198 static inline void clflush(volatile void *__p)
199 {
200 	asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
201 }
202 
clflushopt(volatile void * __p)203 static inline void clflushopt(volatile void *__p)
204 {
205 	alternative_io(".byte 0x3e; clflush %P0",
206 		       ".byte 0x66; clflush %P0",
207 		       X86_FEATURE_CLFLUSHOPT,
208 		       "+m" (*(volatile char __force *)__p));
209 }
210 
clwb(volatile void * __p)211 static inline void clwb(volatile void *__p)
212 {
213 	volatile struct { char x[64]; } *p = __p;
214 
215 	asm volatile(ALTERNATIVE_2(
216 		".byte 0x3e; clflush (%[pax])",
217 		".byte 0x66; clflush (%[pax])", /* clflushopt (%%rax) */
218 		X86_FEATURE_CLFLUSHOPT,
219 		".byte 0x66, 0x0f, 0xae, 0x30",  /* clwb (%%rax) */
220 		X86_FEATURE_CLWB)
221 		: [p] "+m" (*p)
222 		: [pax] "a" (p));
223 }
224 
225 #define nop() asm volatile ("nop")
226 
serialize(void)227 static inline void serialize(void)
228 {
229 	/* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
230 	asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");
231 }
232 
233 /* The dst parameter must be 64-bytes aligned */
movdir64b(void __iomem * dst,const void * src)234 static inline void movdir64b(void __iomem *dst, const void *src)
235 {
236 	const struct { char _[64]; } *__src = src;
237 	struct { char _[64]; } __iomem *__dst = dst;
238 
239 	/*
240 	 * MOVDIR64B %(rdx), rax.
241 	 *
242 	 * Both __src and __dst must be memory constraints in order to tell the
243 	 * compiler that no other memory accesses should be reordered around
244 	 * this one.
245 	 *
246 	 * Also, both must be supplied as lvalues because this tells
247 	 * the compiler what the object is (its size) the instruction accesses.
248 	 * I.e., not the pointers but what they point to, thus the deref'ing '*'.
249 	 */
250 	asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
251 		     : "+m" (*__dst)
252 		     :  "m" (*__src), "a" (__dst), "d" (__src));
253 }
254 
255 /**
256  * enqcmds - Enqueue a command in supervisor (CPL0) mode
257  * @dst: destination, in MMIO space (must be 512-bit aligned)
258  * @src: 512 bits memory operand
259  *
260  * The ENQCMDS instruction allows software to write a 512-bit command to
261  * a 512-bit-aligned special MMIO region that supports the instruction.
262  * A return status is loaded into the ZF flag in the RFLAGS register.
263  * ZF = 0 equates to success, and ZF = 1 indicates retry or error.
264  *
265  * This function issues the ENQCMDS instruction to submit data from
266  * kernel space to MMIO space, in a unit of 512 bits. Order of data access
267  * is not guaranteed, nor is a memory barrier performed afterwards. It
268  * returns 0 on success and -EAGAIN on failure.
269  *
270  * Warning: Do not use this helper unless your driver has checked that the
271  * ENQCMDS instruction is supported on the platform and the device accepts
272  * ENQCMDS.
273  */
enqcmds(void __iomem * dst,const void * src)274 static inline int enqcmds(void __iomem *dst, const void *src)
275 {
276 	const struct { char _[64]; } *__src = src;
277 	struct { char _[64]; } __iomem *__dst = dst;
278 	bool zf;
279 
280 	/*
281 	 * ENQCMDS %(rdx), rax
282 	 *
283 	 * See movdir64b()'s comment on operand specification.
284 	 */
285 	asm volatile(".byte 0xf3, 0x0f, 0x38, 0xf8, 0x02, 0x66, 0x90"
286 		     CC_SET(z)
287 		     : CC_OUT(z) (zf), "+m" (*__dst)
288 		     : "m" (*__src), "a" (__dst), "d" (__src));
289 
290 	/* Submission failure is indicated via EFLAGS.ZF=1 */
291 	if (zf)
292 		return -EAGAIN;
293 
294 	return 0;
295 }
296 
297 #endif /* __KERNEL__ */
298 
299 #endif /* _ASM_X86_SPECIAL_INSNS_H */
300