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, (const void *)from, n);
41	/* KMSAN must treat values read from devices as initialized. */
42	kmsan_unpoison_memory(to, 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(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
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(&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(in[i], &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(b, &mem[i]);
91}
92
93void 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}
100EXPORT_SYMBOL(memcpy_fromio);
101
102void 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}
109EXPORT_SYMBOL(memcpy_toio);
110
111void 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}
123EXPORT_SYMBOL(memset_io);
124