[PATCH 002 of 2] Make copy_from_user_inatomic NOT zero the tail on i386
From: NeilBrown
Date: Thu Apr 27 2006 - 22:10:29 EST
As described in a previous patch and documented in mm/filemap.h,
copy_from_user_inatomic* shouldn't zero out the tail of the buffer
after an incomplete copy.
This patch implements that change for i386.
For the _nocache version, a new __copy_user_intel_nocache is defined
similar to copy_user_zeroio_intel_nocache, and this is ultimately
used for the copy.
For the regular version, __copy_to_user_inatomic is used to implement
__copy_from_user_inatomic as the only difference is that copy_to
doesn't zero the tail, just as we want. Possibly this is a horrible
hack. Comments welcome.
Signed-off-by: Neil Brown <neilb@xxxxxxx>
### Diffstat output
./arch/i386/lib/usercopy.c | 106 +++++++++++++++++++++++++++++++++++++++++++
./include/asm-i386/uaccess.h | 31 +++++++-----
2 files changed, 125 insertions(+), 12 deletions(-)
diff ./arch/i386/lib/usercopy.c~current~ ./arch/i386/lib/usercopy.c
--- ./arch/i386/lib/usercopy.c~current~ 2006-04-28 10:31:13.000000000 +1000
+++ ./arch/i386/lib/usercopy.c 2006-04-28 10:36:34.000000000 +1000
@@ -528,6 +528,97 @@ static unsigned long __copy_user_zeroing
return size;
}
+static unsigned long __copy_user_intel_nocache(void __user *to,
+ const void *from, unsigned long size)
+{
+ int d0, d1;
+
+ __asm__ __volatile__(
+ " .align 2,0x90\n"
+ "0: movl 32(%4), %%eax\n"
+ " cmpl $67, %0\n"
+ " jbe 2f\n"
+ "1: movl 64(%4), %%eax\n"
+ " .align 2,0x90\n"
+ "2: movl 0(%4), %%eax\n"
+ "21: movl 4(%4), %%edx\n"
+ " movnti %%eax, 0(%3)\n"
+ " movnti %%edx, 4(%3)\n"
+ "3: movl 8(%4), %%eax\n"
+ "31: movl 12(%4),%%edx\n"
+ " movnti %%eax, 8(%3)\n"
+ " movnti %%edx, 12(%3)\n"
+ "4: movl 16(%4), %%eax\n"
+ "41: movl 20(%4), %%edx\n"
+ " movnti %%eax, 16(%3)\n"
+ " movnti %%edx, 20(%3)\n"
+ "10: movl 24(%4), %%eax\n"
+ "51: movl 28(%4), %%edx\n"
+ " movnti %%eax, 24(%3)\n"
+ " movnti %%edx, 28(%3)\n"
+ "11: movl 32(%4), %%eax\n"
+ "61: movl 36(%4), %%edx\n"
+ " movnti %%eax, 32(%3)\n"
+ " movnti %%edx, 36(%3)\n"
+ "12: movl 40(%4), %%eax\n"
+ "71: movl 44(%4), %%edx\n"
+ " movnti %%eax, 40(%3)\n"
+ " movnti %%edx, 44(%3)\n"
+ "13: movl 48(%4), %%eax\n"
+ "81: movl 52(%4), %%edx\n"
+ " movnti %%eax, 48(%3)\n"
+ " movnti %%edx, 52(%3)\n"
+ "14: movl 56(%4), %%eax\n"
+ "91: movl 60(%4), %%edx\n"
+ " movnti %%eax, 56(%3)\n"
+ " movnti %%edx, 60(%3)\n"
+ " addl $-64, %0\n"
+ " addl $64, %4\n"
+ " addl $64, %3\n"
+ " cmpl $63, %0\n"
+ " ja 0b\n"
+ " sfence \n"
+ "5: movl %0, %%eax\n"
+ " shrl $2, %0\n"
+ " andl $3, %%eax\n"
+ " cld\n"
+ "6: rep; movsl\n"
+ " movl %%eax,%0\n"
+ "7: rep; movsb\n"
+ "8:\n"
+ ".section .fixup,\"ax\"\n"
+ "9: lea 0(%%eax,%0,4),%0\n"
+ "16: jmp 8b\n"
+ ".previous\n"
+ ".section __ex_table,\"a\"\n"
+ " .align 4\n"
+ " .long 0b,16b\n"
+ " .long 1b,16b\n"
+ " .long 2b,16b\n"
+ " .long 21b,16b\n"
+ " .long 3b,16b\n"
+ " .long 31b,16b\n"
+ " .long 4b,16b\n"
+ " .long 41b,16b\n"
+ " .long 10b,16b\n"
+ " .long 51b,16b\n"
+ " .long 11b,16b\n"
+ " .long 61b,16b\n"
+ " .long 12b,16b\n"
+ " .long 71b,16b\n"
+ " .long 13b,16b\n"
+ " .long 81b,16b\n"
+ " .long 14b,16b\n"
+ " .long 91b,16b\n"
+ " .long 6b,9b\n"
+ " .long 7b,16b\n"
+ ".previous"
+ : "=&c"(size), "=&D" (d0), "=&S" (d1)
+ : "1"(to), "2"(from), "0"(size)
+ : "eax", "edx", "memory");
+ return size;
+}
+
#else
/*
@@ -709,6 +800,21 @@ unsigned long __copy_from_user_ll_nocach
return n;
}
+unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from,
+ unsigned long n)
+{
+ BUG_ON((long)n < 0);
+#ifdef CONFIG_X86_INTEL_USERCOPY
+ if ( n > 64 && cpu_has_xmm2)
+ n = __copy_user_intel_nocache(to, from, n);
+ else
+ __copy_user(to, from, n);
+#else
+ __copy_user(to, from, n);
+#endif
+ return n;
+}
+
/**
* copy_to_user: - Copy a block of data into user space.
* @to: Destination address, in user space.
diff ./include/asm-i386/uaccess.h~current~ ./include/asm-i386/uaccess.h
--- ./include/asm-i386/uaccess.h~current~ 2006-04-28 10:08:04.000000000 +1000
+++ ./include/asm-i386/uaccess.h 2006-04-28 10:37:12.000000000 +1000
@@ -393,6 +393,8 @@ unsigned long __must_check __copy_from_u
const void __user *from, unsigned long n);
unsigned long __must_check __copy_from_user_ll_nocache(void *to,
const void __user *from, unsigned long n);
+unsigned long __must_check __copy_from_user_ll_nocache_nozero(void __user *to,
+ const void *from, unsigned long n);
/*
* Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
@@ -464,11 +466,23 @@ __copy_to_user(void __user *to, const vo
* atomic context and will fail rather than sleep. In this case the
* uncopied bytes will *NOT* be padded with zeros. See fs/filemap.h
* for explanation of why this is needed.
- * FIXME this isn't implimented yet EMXIF
*/
static __always_inline unsigned long
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
{
+ /* As the only difference between copy_from and copy_to is that
+ * copy_from zeros any tail that wasn't actually copied to,
+ * and as that is exactly what we want for inatomic copy_from,
+ * we use copy_to_user_inatomic to implement
+ * copy_from_user_inatomic. Ofcourse we need to lie about
+ * __user tags....
+ */
+ return __copy_to_user_inatomic((void __user*)to, (const void *)from, n);
+}
+static __always_inline unsigned long
+__copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+ might_sleep();
if (__builtin_constant_p(n)) {
unsigned long ret;
@@ -489,9 +503,10 @@ __copy_from_user_inatomic(void *to, cons
#define ARCH_HAS_NOCACHE_UACCESS
-static __always_inline unsigned long __copy_from_user_inatomic_nocache(void *to,
+static __always_inline unsigned long __copy_from_user_nocache(void *to,
const void __user *from, unsigned long n)
{
+ might_sleep();
if (__builtin_constant_p(n)) {
unsigned long ret;
@@ -511,17 +526,9 @@ static __always_inline unsigned long __c
}
static __always_inline unsigned long
-__copy_from_user(void *to, const void __user *from, unsigned long n)
-{
- might_sleep();
- return __copy_from_user_inatomic(to, from, n);
-}
-
-static __always_inline unsigned long
-__copy_from_user_nocache(void *to, const void __user *from, unsigned long n)
+__copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
{
- might_sleep();
- return __copy_from_user_inatomic_nocache(to, from, n);
+ return __copy_from_user_ll_nocache_nozero((void __user *)to, (const void *)from, n);
}
unsigned long __must_check copy_to_user(void __user *to,
-
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