x86/lib/iomem.c

0001 #include <linux/string.h>
0002 #include <linux/module.h>
0003 #include <linux/io.h>
0004
0005 #define movs(type,to,from) \
0006     asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
0007
0008 /* Originally from i386/string.h */
0009 static __always_inline void rep_movs(void *to, const void *from, size_t n)
0010 {
0011     unsigned long d0, d1, d2;
0012     asm volatile("rep ; movsl\n\t"
0013              "testb $2,%b4\n\t"
0014              "je 1f\n\t"
0015              "movsw\n"
0016              "1:\ttestb $1,%b4\n\t"
0017              "je 2f\n\t"
0018              "movsb\n"
0019              "2:"
0020              : "=&c" (d0), "=&D" (d1), "=&S" (d2)
0021              : "0" (n / 4), "q" (n), "1" ((long)to), "2" ((long)from)
0022              : "memory");
0023 }
0024
0025 static void string_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
0026 {
0027     if (unlikely(!n))
0028         return;
0029
0030     /* Align any unaligned source IO */
0031     if (unlikely(1 & (unsigned long)from)) {
0032         movs("b", to, from);
0033         n--;
0034     }
0035     if (n > 1 && unlikely(2 & (unsigned long)from)) {
0036         movs("w", to, from);
0037         n-=2;
0038     }
0039     rep_movs(to, (const void *)from, n);
0040 }
0041
0042 static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
0043 {
0044     if (unlikely(!n))
0045         return;
0046
0047     /* Align any unaligned destination IO */
0048     if (unlikely(1 & (unsigned long)to)) {
0049         movs("b", to, from);
0050         n--;
0051     }
0052     if (n > 1 && unlikely(2 & (unsigned long)to)) {
0053         movs("w", to, from);
0054         n-=2;
0055     }
0056     rep_movs((void *)to, (const void *) from, n);
0057 }
0058
0059 static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
0060 {
0061     const volatile char __iomem *in = from;
0062     char *out = to;
0063     int i;
0064
0065     for (i = 0; i < n; ++i)
0066         out[i] = readb(&in[i]);
0067 }
0068
0069 static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
0070 {
0071     volatile char __iomem *out = to;
0072     const char *in = from;
0073     int i;
0074
0075     for (i = 0; i < n; ++i)
0076         writeb(in[i], &out[i]);
0077 }
0078
0079 static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c)
0080 {
0081     volatile char __iomem *mem = a;
0082     int i;
0083
0084     for (i = 0; i < c; ++i)
0085         writeb(b, &mem[i]);
0086 }
0087
0088 void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
0089 {
0090     if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
0091         unrolled_memcpy_fromio(to, from, n);
0092     else
0093         string_memcpy_fromio(to, from, n);
0094 }
0095 EXPORT_SYMBOL(memcpy_fromio);
0096
0097 void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
0098 {
0099     if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
0100         unrolled_memcpy_toio(to, from, n);
0101     else
0102         string_memcpy_toio(to, from, n);
0103 }
0104 EXPORT_SYMBOL(memcpy_toio);
0105
0106 void memset_io(volatile void __iomem *a, int b, size_t c)
0107 {
0108     if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) {
0109         unrolled_memset_io(a, b, c);
0110     } else {
0111         /*
0112          * TODO: memset can mangle the IO patterns quite a bit.
0113          * perhaps it would be better to use a dumb one:
0114          */
0115         memset((void *)a, b, c);
0116     }
0117 }
0118 EXPORT_SYMBOL(memset_io);