1 #include <linux/string.h>
2 #include <linux/module.h>
3 #include <linux/io.h>
4 #include <linux/kmsan-checks.h>
5 
6 #define movs(type,to,from) \
7 	asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
8 
9 /* Originally from i386/string.h */
rep_movs(void * to,const void * from,size_t n)10 static __always_inline void rep_movs(void *to, const void *from, size_t n)
11 {
12 	unsigned long d0, d1, d2;
13 	asm volatile("rep ; movsl\n\t"
14 		     "testb $2,%b4\n\t"
15 		     "je 1f\n\t"
16 		     "movsw\n"
17 		     "1:\ttestb $1,%b4\n\t"
18 		     "je 2f\n\t"
19 		     "movsb\n"
20 		     "2:"
21 		     : "=&c" (d0), "=&D" (d1), "=&S" (d2)
22 		     : "0" (n / 4), "q" (n), "1" ((long)to), "2" ((long)from)
23 		     : "memory");
24 }
25 
string_memcpy_fromio(void * to,const volatile void __iomem * from,size_t n)26 static void string_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
27 {
28 	if (unlikely(!n))
29 		return;
30 
31 	/* Align any unaligned source IO */
32 	if (unlikely(1 & (unsigned long)from)) {
33 		movs("b", to, from);
34 		n--;
35 	}
36 	if (n > 1 && unlikely(2 & (unsigned long)from)) {
37 		movs("w", to, from);
38 		n-=2;
39 	}
40 	rep_movs(to, (const void *)from, n);
41 	/* KMSAN must treat values read from devices as initialized. */
42 	kmsan_unpoison_memory(to, n);
43 }
44 
string_memcpy_toio(volatile void __iomem * to,const void * from,size_t n)45 static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
46 {
47 	if (unlikely(!n))
48 		return;
49 
50 	/* Make sure uninitialized memory isn't copied to devices. */
51 	kmsan_check_memory(from, n);
52 	/* Align any unaligned destination IO */
53 	if (unlikely(1 & (unsigned long)to)) {
54 		movs("b", to, from);
55 		n--;
56 	}
57 	if (n > 1 && unlikely(2 & (unsigned long)to)) {
58 		movs("w", to, from);
59 		n-=2;
60 	}
61 	rep_movs((void *)to, (const void *) from, n);
62 }
63 
unrolled_memcpy_fromio(void * to,const volatile void __iomem * from,size_t n)64 static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
65 {
66 	const volatile char __iomem *in = from;
67 	char *out = to;
68 	int i;
69 
70 	for (i = 0; i < n; ++i)
71 		out[i] = readb(&in[i]);
72 }
73 
unrolled_memcpy_toio(volatile void __iomem * to,const void * from,size_t n)74 static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
75 {
76 	volatile char __iomem *out = to;
77 	const char *in = from;
78 	int i;
79 
80 	for (i = 0; i < n; ++i)
81 		writeb(in[i], &out[i]);
82 }
83 
unrolled_memset_io(volatile void __iomem * a,int b,size_t c)84 static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c)
85 {
86 	volatile char __iomem *mem = a;
87 	int i;
88 
89 	for (i = 0; i < c; ++i)
90 		writeb(b, &mem[i]);
91 }
92 
memcpy_fromio(void * to,const volatile void __iomem * from,size_t n)93 void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
94 {
95 	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
96 		unrolled_memcpy_fromio(to, from, n);
97 	else
98 		string_memcpy_fromio(to, from, n);
99 }
100 EXPORT_SYMBOL(memcpy_fromio);
101 
memcpy_toio(volatile void __iomem * to,const void * from,size_t n)102 void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
103 {
104 	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
105 		unrolled_memcpy_toio(to, from, n);
106 	else
107 		string_memcpy_toio(to, from, n);
108 }
109 EXPORT_SYMBOL(memcpy_toio);
110 
memset_io(volatile void __iomem * a,int b,size_t c)111 void memset_io(volatile void __iomem *a, int b, size_t c)
112 {
113 	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) {
114 		unrolled_memset_io(a, b, c);
115 	} else {
116 		/*
117 		 * TODO: memset can mangle the IO patterns quite a bit.
118 		 * perhaps it would be better to use a dumb one:
119 		 */
120 		memset((void *)a, b, c);
121 	}
122 }
123 EXPORT_SYMBOL(memset_io);
124