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);