mirror of
https://github.com/torvalds/linux.git
synced 2024-11-21 19:46:16 +00:00
bf6ab33d84
When called with a 'from' that is not 4-byte-aligned, string_memcpy_fromio() calls the movs() macro to copy the first few bytes, so that 'from' becomes 4-byte-aligned before calling rep_movs(). This movs() macro modifies 'to', and the subsequent line modifies 'n'. As a result, on unaligned accesses, kmsan_unpoison_memory() uses the updated (aligned) values of 'to' and 'n'. Hence, it does not unpoison the entire region. Save the original values of 'to' and 'n', and pass those to kmsan_unpoison_memory(), so that the entire region is unpoisoned. Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Alexander Potapenko <glider@google.com> Link: https://lore.kernel.org/r/20240523215029.4160518-1-bjohannesmeyer@gmail.com
127 lines
3.0 KiB
C
127 lines
3.0 KiB
C
#include <linux/string.h>
|
|
#include <linux/module.h>
|
|
#include <linux/io.h>
|
|
#include <linux/kmsan-checks.h>
|
|
|
|
#define movs(type,to,from) \
|
|
asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
|
|
|
|
/* Originally from i386/string.h */
|
|
static __always_inline void rep_movs(void *to, const void *from, size_t n)
|
|
{
|
|
unsigned long d0, d1, d2;
|
|
asm volatile("rep ; movsl\n\t"
|
|
"testb $2,%b4\n\t"
|
|
"je 1f\n\t"
|
|
"movsw\n"
|
|
"1:\ttestb $1,%b4\n\t"
|
|
"je 2f\n\t"
|
|
"movsb\n"
|
|
"2:"
|
|
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
|
|
: "0" (n / 4), "q" (n), "1" ((long)to), "2" ((long)from)
|
|
: "memory");
|
|
}
|
|
|
|
static void string_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
|
|
{
|
|
const void *orig_to = to;
|
|
const size_t orig_n = n;
|
|
|
|
if (unlikely(!n))
|
|
return;
|
|
|
|
/* Align any unaligned source IO */
|
|
if (unlikely(1 & (unsigned long)from)) {
|
|
movs("b", to, from);
|
|
n--;
|
|
}
|
|
if (n > 1 && unlikely(2 & (unsigned long)from)) {
|
|
movs("w", to, from);
|
|
n-=2;
|
|
}
|
|
rep_movs(to, (const void *)from, n);
|
|
/* KMSAN must treat values read from devices as initialized. */
|
|
kmsan_unpoison_memory(orig_to, orig_n);
|
|
}
|
|
|
|
static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
|
|
{
|
|
if (unlikely(!n))
|
|
return;
|
|
|
|
/* Make sure uninitialized memory isn't copied to devices. */
|
|
kmsan_check_memory(from, n);
|
|
/* Align any unaligned destination IO */
|
|
if (unlikely(1 & (unsigned long)to)) {
|
|
movs("b", to, from);
|
|
n--;
|
|
}
|
|
if (n > 1 && unlikely(2 & (unsigned long)to)) {
|
|
movs("w", to, from);
|
|
n-=2;
|
|
}
|
|
rep_movs((void *)to, (const void *) from, n);
|
|
}
|
|
|
|
static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
|
|
{
|
|
const volatile char __iomem *in = from;
|
|
char *out = to;
|
|
int i;
|
|
|
|
for (i = 0; i < n; ++i)
|
|
out[i] = readb(&in[i]);
|
|
}
|
|
|
|
static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
|
|
{
|
|
volatile char __iomem *out = to;
|
|
const char *in = from;
|
|
int i;
|
|
|
|
for (i = 0; i < n; ++i)
|
|
writeb(in[i], &out[i]);
|
|
}
|
|
|
|
static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c)
|
|
{
|
|
volatile char __iomem *mem = a;
|
|
int i;
|
|
|
|
for (i = 0; i < c; ++i)
|
|
writeb(b, &mem[i]);
|
|
}
|
|
|
|
void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
|
|
{
|
|
if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
|
|
unrolled_memcpy_fromio(to, from, n);
|
|
else
|
|
string_memcpy_fromio(to, from, n);
|
|
}
|
|
EXPORT_SYMBOL(memcpy_fromio);
|
|
|
|
void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
|
|
{
|
|
if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
|
|
unrolled_memcpy_toio(to, from, n);
|
|
else
|
|
string_memcpy_toio(to, from, n);
|
|
}
|
|
EXPORT_SYMBOL(memcpy_toio);
|
|
|
|
void memset_io(volatile void __iomem *a, int b, size_t c)
|
|
{
|
|
if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) {
|
|
unrolled_memset_io(a, b, c);
|
|
} else {
|
|
/*
|
|
* TODO: memset can mangle the IO patterns quite a bit.
|
|
* perhaps it would be better to use a dumb one:
|
|
*/
|
|
memset((void *)a, b, c);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(memset_io);
|