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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86: streamline copying to/from user memory
commit 2fdf5b25540f649ea8a41e4fdfb13cf399614af8
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 16 14:32:51 2016 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 16 14:32:51 2016 +0100
x86: streamline copying to/from user memory
Their size parameters being "unsigned", there's neither a point for
them returning "unsigned long", nor for any of their (assembly)
arithmetic to involved 64-bit operations on other than addresses.
Take the opportunity and fold __do_clear_user() into its single user
(using qword stores instead of dword ones), name all asm() operands,
and reduce the amount of (redundant) operands.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/usercopy.c | 138 ++++++++++++++++++++----------------------
xen/include/asm-x86/uaccess.h | 10 +--
2 files changed, 72 insertions(+), 76 deletions(-)
diff --git a/xen/arch/x86/usercopy.c b/xen/arch/x86/usercopy.c
index 4cc78f5..d1303a9 100644
--- a/xen/arch/x86/usercopy.c
+++ b/xen/arch/x86/usercopy.c
@@ -10,87 +10,88 @@
#include <xen/sched.h>
#include <asm/uaccess.h>
-unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned n)
+unsigned __copy_to_user_ll(void __user *to, const void *from, unsigned n)
{
- unsigned long __d0, __d1, __d2, __n = n;
+ unsigned dummy;
stac();
asm volatile (
- " cmp $"STR(2*BYTES_PER_LONG-1)",%0\n"
+ " cmp $"STR(2*BYTES_PER_LONG-1)", %[cnt]\n"
" jbe 1f\n"
- " mov %1,%0\n"
- " neg %0\n"
- " and $"STR(BYTES_PER_LONG-1)",%0\n"
- " sub %0,%3\n"
+ " mov %k[to], %[cnt]\n"
+ " neg %[cnt]\n"
+ " and $"STR(BYTES_PER_LONG-1)", %[cnt]\n"
+ " sub %[cnt], %[aux]\n"
"4: rep movsb\n" /* make 'to' address aligned */
- " mov %3,%0\n"
- " shr $"STR(LONG_BYTEORDER)",%0\n"
- " and $"STR(BYTES_PER_LONG-1)",%3\n"
+ " mov %[aux], %[cnt]\n"
+ " shr $"STR(LONG_BYTEORDER)", %[cnt]\n"
+ " and $"STR(BYTES_PER_LONG-1)", %[aux]\n"
" .align 2,0x90\n"
"0: rep movs"__OS"\n" /* as many words as possible... */
- " mov %3,%0\n"
+ " mov %[aux],%[cnt]\n"
"1: rep movsb\n" /* ...remainder copied as bytes */
"2:\n"
".section .fixup,\"ax\"\n"
- "5: add %3,%0\n"
+ "5: add %[aux], %[cnt]\n"
" jmp 2b\n"
- "3: lea 0(%3,%0,"STR(BYTES_PER_LONG)"),%0\n"
+ "3: lea (%q[aux], %q[cnt], "STR(BYTES_PER_LONG)"), %[cnt]\n"
" jmp 2b\n"
".previous\n"
_ASM_EXTABLE(4b, 5b)
_ASM_EXTABLE(0b, 3b)
_ASM_EXTABLE(1b, 2b)
- : "=&c" (__n), "=&D" (__d0), "=&S" (__d1), "=&r" (__d2)
- : "0" (__n), "1" (to), "2" (from), "3" (__n)
+ : [cnt] "+c" (n), [to] "+D" (to), [from] "+S" (from),
+ [aux] "=&r" (dummy)
+ : "[aux]" (n)
: "memory" );
clac();
- return __n;
+ return n;
}
-unsigned long
-__copy_from_user_ll(void *to, const void __user *from, unsigned n)
+unsigned __copy_from_user_ll(void *to, const void __user *from, unsigned n)
{
- unsigned long __d0, __d1, __d2, __n = n;
+ unsigned dummy;
stac();
asm volatile (
- " cmp $"STR(2*BYTES_PER_LONG-1)",%0\n"
+ " cmp $"STR(2*BYTES_PER_LONG-1)", %[cnt]\n"
" jbe 1f\n"
- " mov %1,%0\n"
- " neg %0\n"
- " and $"STR(BYTES_PER_LONG-1)",%0\n"
- " sub %0,%3\n"
- "4: rep; movsb\n" /* make 'to' address aligned */
- " mov %3,%0\n"
- " shr $"STR(LONG_BYTEORDER)",%0\n"
- " and $"STR(BYTES_PER_LONG-1)",%3\n"
+ " mov %k[to], %[cnt]\n"
+ " neg %[cnt]\n"
+ " and $"STR(BYTES_PER_LONG-1)", %[cnt]\n"
+ " sub %[cnt], %[aux]\n"
+ "4: rep movsb\n" /* make 'to' address aligned */
+ " mov %[aux],%[cnt]\n"
+ " shr $"STR(LONG_BYTEORDER)", %[cnt]\n"
+ " and $"STR(BYTES_PER_LONG-1)", %[aux]\n"
" .align 2,0x90\n"
- "0: rep; movs"__OS"\n" /* as many words as possible... */
- " mov %3,%0\n"
- "1: rep; movsb\n" /* ...remainder copied as bytes */
+ "0: rep movs"__OS"\n" /* as many words as possible... */
+ " mov %[aux], %[cnt]\n"
+ "1: rep movsb\n" /* ...remainder copied as bytes */
"2:\n"
".section .fixup,\"ax\"\n"
- "5: add %3,%0\n"
+ "5: add %[aux], %[cnt]\n"
" jmp 6f\n"
- "3: lea 0(%3,%0,"STR(BYTES_PER_LONG)"),%0\n"
- "6: push %0\n"
- " push %%"__OP"ax\n"
- " xor %%eax,%%eax\n"
- " rep; stosb\n"
- " pop %%"__OP"ax\n"
- " pop %0\n"
+ "3: lea (%q[aux], %q[cnt], "STR(BYTES_PER_LONG)"), %[cnt]\n"
+ "6: mov %[cnt], %k[from]\n"
+ " xchg %%eax, %[aux]\n"
+ " xor %%eax, %%eax\n"
+ " rep stosb\n"
+ " xchg %[aux], %%eax\n"
+ " mov %k[from], %[cnt]\n"
" jmp 2b\n"
".previous\n"
_ASM_EXTABLE(4b, 5b)
_ASM_EXTABLE(0b, 3b)
_ASM_EXTABLE(1b, 6b)
- : "=&c" (__n), "=&D" (__d0), "=&S" (__d1), "=&r" (__d2)
- : "0" (__n), "1" (to), "2" (from), "3" (__n)
+ : [cnt] "+c" (n), [to] "+D" (to), [from] "+S" (from),
+ [aux] "=&r" (dummy)
+ : "[aux]" (n)
: "memory" );
clac();
- return __n;
+ return n;
}
/**
@@ -106,34 +107,13 @@ __copy_from_user_ll(void *to, const void __user *from,
unsigned n)
* Returns number of bytes that could not be copied.
* On success, this will be zero.
*/
-unsigned long
-copy_to_user(void __user *to, const void *from, unsigned n)
+unsigned copy_to_user(void __user *to, const void *from, unsigned n)
{
if ( access_ok(to, n) )
n = __copy_to_user(to, from, n);
return n;
}
-#define __do_clear_user(addr,size) \
-do { \
- long __d0; \
- stac(); \
- __asm__ __volatile__( \
- "0: rep; stosl\n" \
- " movl %2,%0\n" \
- "1: rep; stosb\n" \
- "2:\n" \
- ".section .fixup,\"ax\"\n" \
- "3: lea 0(%2,%0,4),%0\n" \
- " jmp 2b\n" \
- ".previous\n" \
- _ASM_EXTABLE(0b,3b) \
- _ASM_EXTABLE(1b,2b) \
- : "=&c"(size), "=&D" (__d0) \
- : "r"(size & 3), "0"(size / 4), "1"((long)addr), "a"(0));
\
- clac(); \
-} while (0)
-
/**
* clear_user: - Zero a block of memory in user space.
* @to: Destination address, in user space.
@@ -144,12 +124,29 @@ do {
\
* Returns number of bytes that could not be cleared.
* On success, this will be zero.
*/
-unsigned long
-clear_user(void __user *to, unsigned n)
+unsigned clear_user(void __user *to, unsigned n)
{
- if ( access_ok(to, n) )
- __do_clear_user(to, n);
- return n;
+ if ( access_ok(to, n) )
+ {
+ stac();
+ asm volatile (
+ "0: rep stos"__OS"\n"
+ " mov %[bytes], %[cnt]\n"
+ "1: rep stosb\n"
+ "2:\n"
+ ".section .fixup,\"ax\"\n"
+ "3: lea (%q[bytes], %q[longs], "STR(BYTES_PER_LONG)"), %[cnt]\n"
+ " jmp 2b\n"
+ ".previous\n"
+ _ASM_EXTABLE(0b,3b)
+ _ASM_EXTABLE(1b,2b)
+ : [cnt] "=&c" (n), [to] "+D" (to)
+ : [bytes] "g" (n & (BYTES_PER_LONG - 1)),
+ [longs] "0" (n / BYTES_PER_LONG), "a" (0) );
+ clac();
+ }
+
+ return n;
}
/**
@@ -168,8 +165,7 @@ clear_user(void __user *to, unsigned n)
* If some data could not be copied, this function will pad the copied
* data to the requested size using zero bytes.
*/
-unsigned long
-copy_from_user(void *to, const void __user *from, unsigned n)
+unsigned copy_from_user(void *to, const void __user *from, unsigned n)
{
if ( access_ok(from, n) )
n = __copy_from_user(to, from, n);
diff --git a/xen/include/asm-x86/uaccess.h b/xen/include/asm-x86/uaccess.h
index 5df26c2..9a01198 100644
--- a/xen/include/asm-x86/uaccess.h
+++ b/xen/include/asm-x86/uaccess.h
@@ -11,12 +11,12 @@
#include <asm/x86_64/uaccess.h>
-unsigned long copy_to_user(void *to, const void *from, unsigned len);
-unsigned long clear_user(void *to, unsigned len);
-unsigned long copy_from_user(void *to, const void *from, unsigned len);
+unsigned copy_to_user(void *to, const void *from, unsigned len);
+unsigned clear_user(void *to, unsigned len);
+unsigned copy_from_user(void *to, const void *from, unsigned len);
/* Handles exceptions in both to and from, but doesn't do access_ok */
-unsigned long __copy_to_user_ll(void *to, const void *from, unsigned n);
-unsigned long __copy_from_user_ll(void *to, const void *from, unsigned n);
+unsigned __copy_to_user_ll(void __user*to, const void *from, unsigned n);
+unsigned __copy_from_user_ll(void *to, const void __user *from, unsigned n);
extern long __get_user_bad(void);
extern void __put_user_bad(void);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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