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 */
10static __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
26static 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, from: (const void *)from, n);
41 /* KMSAN must treat values read from devices as initialized. */
42 kmsan_unpoison_memory(address: to, size: n);
43}
44
45static 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(address: from, size: 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(to: (void *)to, from: (const void *) from, n);
62}
63
64static 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(addr: &in[i]);
72}
73
74static 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(val: in[i], addr: &out[i]);
82}
83
84static 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(val: b, addr: &mem[i]);
91}
92
93void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
94{
95 if (cc_platform_has(attr: CC_ATTR_GUEST_UNROLL_STRING_IO))
96 unrolled_memcpy_fromio(to, from, n);
97 else
98 string_memcpy_fromio(to, from, n);
99}
100EXPORT_SYMBOL(memcpy_fromio);
101
102void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
103{
104 if (cc_platform_has(attr: CC_ATTR_GUEST_UNROLL_STRING_IO))
105 unrolled_memcpy_toio(to, from, n);
106 else
107 string_memcpy_toio(to, from, n);
108}
109EXPORT_SYMBOL(memcpy_toio);
110
111void memset_io(volatile void __iomem *a, int b, size_t c)
112{
113 if (cc_platform_has(attr: 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}
123EXPORT_SYMBOL(memset_io);
124

source code of linux/arch/x86/lib/iomem.c