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 const void *orig_to = to;
29 const size_t orig_n = n;
30
31 if (unlikely(!n))
32 return;
33
34 /* Align any unaligned source IO */
35 if (unlikely(1 & (unsigned long)from)) {
36 movs("b", to, from);
37 n--;
38 }
39 if (n > 1 && unlikely(2 & (unsigned long)from)) {
40 movs("w", to, from);
41 n-=2;
42 }
43 rep_movs(to, (const void *)from, n);
44 /* KMSAN must treat values read from devices as initialized. */
45 kmsan_unpoison_memory(orig_to, orig_n);
46 }
47
string_memcpy_toio(volatile void __iomem * to,const void * from,size_t n)48 static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
49 {
50 if (unlikely(!n))
51 return;
52
53 /* Make sure uninitialized memory isn't copied to devices. */
54 kmsan_check_memory(from, n);
55 /* Align any unaligned destination IO */
56 if (unlikely(1 & (unsigned long)to)) {
57 movs("b", to, from);
58 n--;
59 }
60 if (n > 1 && unlikely(2 & (unsigned long)to)) {
61 movs("w", to, from);
62 n-=2;
63 }
64 rep_movs((void *)to, (const void *) from, n);
65 }
66
unrolled_memcpy_fromio(void * to,const volatile void __iomem * from,size_t n)67 static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
68 {
69 const volatile char __iomem *in = from;
70 char *out = to;
71 int i;
72
73 for (i = 0; i < n; ++i)
74 out[i] = readb(&in[i]);
75 }
76
unrolled_memcpy_toio(volatile void __iomem * to,const void * from,size_t n)77 static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
78 {
79 volatile char __iomem *out = to;
80 const char *in = from;
81 int i;
82
83 for (i = 0; i < n; ++i)
84 writeb(in[i], &out[i]);
85 }
86
unrolled_memset_io(volatile void __iomem * a,int b,size_t c)87 static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c)
88 {
89 volatile char __iomem *mem = a;
90 int i;
91
92 for (i = 0; i < c; ++i)
93 writeb(b, &mem[i]);
94 }
95
memcpy_fromio(void * to,const volatile void __iomem * from,size_t n)96 void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
97 {
98 if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
99 unrolled_memcpy_fromio(to, from, n);
100 else
101 string_memcpy_fromio(to, from, n);
102 }
103 EXPORT_SYMBOL(memcpy_fromio);
104
memcpy_toio(volatile void __iomem * to,const void * from,size_t n)105 void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
106 {
107 if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
108 unrolled_memcpy_toio(to, from, n);
109 else
110 string_memcpy_toio(to, from, n);
111 }
112 EXPORT_SYMBOL(memcpy_toio);
113
memset_io(volatile void __iomem * a,int b,size_t c)114 void memset_io(volatile void __iomem *a, int b, size_t c)
115 {
116 if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) {
117 unrolled_memset_io(a, b, c);
118 } else {
119 /*
120 * TODO: memset can mangle the IO patterns quite a bit.
121 * perhaps it would be better to use a dumb one:
122 */
123 memset((void *)a, b, c);
124 }
125 }
126 EXPORT_SYMBOL(memset_io);
127