Currently memset() is used to fill a user space area (clear_user) or
kernel one (memset). These two functions don't have the same
prototype, the former returning the number of bytes not copied and the
latter returning the start address of the area to clear. This forces
memset() to actually returns two values in an unconventional way ie
the number of bytes not copied is given by $a2. Therefore clear_user()
needs to call memset() using inline assembly.
Instead this patch creates __fill_user() which is the same as memset()
except it always returns the number of bytes not copied. This simplify
clear_user() and makes its definition saner.
Also an out of line version of memset is given because gcc generates
some calls to it since builtin functions have been disabled. It allows
assembly code to call it too.
Eventually __bzero() has been removed because it's not part of the
Linux uaccess API. And the nano-optimization it brings is not
worthing.
Signed-off-by: Franck Bui-Huu <fbuihuu@xxxxxxxxx>
---
arch/mips/kernel/mips_ksyms.c | 3 +-
arch/mips/lib/csum_partial.S | 2 +-
arch/mips/lib/memcpy.S | 2 +-
arch/mips/lib/memset.S | 49 ++++++++++++++++++++++++++--------------
include/asm-mips/string.h | 7 +++++-
include/asm-mips/uaccess.h | 17 ++-----------
6 files changed, 44 insertions(+), 36 deletions(-)
diff --git a/arch/mips/kernel/mips_ksyms.c b/arch/mips/kernel/mips_ksyms.c
index 225755d..a801e09 100644
--- a/arch/mips/kernel/mips_ksyms.c
+++ b/arch/mips/kernel/mips_ksyms.c
@@ -14,7 +14,6 @@
#include <asm/pgtable.h>
#include <asm/uaccess.h>
-extern void *__bzero(void *__s, size_t __count);
extern long __strncpy_from_user_nocheck_asm(char *__to,
const char *__from, long __len);
extern long __strncpy_from_user_asm(char *__to, const char *__from,
@@ -36,9 +35,9 @@ EXPORT_SYMBOL(kernel_thread);
/*
* Userspace access stuff.
*/
+EXPORT_SYMBOL(__fill_user);
EXPORT_SYMBOL(__copy_user);
EXPORT_SYMBOL(__copy_user_inatomic);
-EXPORT_SYMBOL(__bzero);
EXPORT_SYMBOL(__strncpy_from_user_nocheck_asm);
EXPORT_SYMBOL(__strncpy_from_user_asm);
EXPORT_SYMBOL(__strlen_user_nocheck_asm);
diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index c0a77fe..8d3fa1e 100644
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -694,7 +694,7 @@ l_exc:
ADD dst, t0 # compute start address in a1
SUB dst, src
/*
- * Clear len bytes starting at dst. Can't call __bzero because it
+ * Clear len bytes starting at dst. Can't call memset because it
* might modify len. An inefficient loop for these rare times...
*/
beqz len, done
diff --git a/arch/mips/lib/memcpy.S b/arch/mips/lib/memcpy.S
index a526c62..425f2c3 100644
--- a/arch/mips/lib/memcpy.S
+++ b/arch/mips/lib/memcpy.S
@@ -443,7 +443,7 @@ l_exc:
ADD dst, t0 # compute start address in a1
SUB dst, src
/*
- * Clear len bytes starting at dst. Can't call __bzero because it
+ * Clear len bytes starting at dst. Can't call memset because it
* might modify len. An inefficient loop for these rare times...
*/
beqz len, done
diff --git a/arch/mips/lib/memset.S b/arch/mips/lib/memset.S
index 3f8b8b3..cb6b83d 100644
--- a/arch/mips/lib/memset.S
+++ b/arch/mips/lib/memset.S
@@ -46,17 +46,34 @@
.endm
/*
- * memset(void *s, int c, size_t n)
+ * An outline version of memset, which should be used either by gcc or
+ * by assembly code.
+ */
+NESTED(memset, 24, ra)
+ PTR_ADDU sp, sp, -24
+ LONG_S a0, 16(sp)
+ LONG_S ra, 20(sp)
+ jal __fill_user
+ LONG_L v0, 16(sp)
+ LONG_L ra, 20(sp)
+ PTR_ADDU sp, sp, 24
+ jr ra
+END(memset)
+
+/*
+ * __kernel_size_t __fill_user(void __user *s, long c, __kernel_size_t n)
*
* a0: start of area to clear
* a1: char to fill with
* a2: size of area to clear
+ *
+ * Returns the number of bytes NOT set or 0 on success.
*/
.set noreorder
.align 5
-LEAF(memset)
+LEAF(__fill_user)
beqz a1, 1f
- move v0, a0 /* result */
+ move v0, zero /* result */
andi a1, 0xff /* spread fillword */
LONG_SLL t1, a1, 8
@@ -68,8 +85,6 @@ LEAF(memset)
#endif
or a1, t1
1:
-
-FEXPORT(__bzero)
sltiu t0, a2, LONGSIZE /* very small region? */
bnez t0, small_memset
andi t0, a0, LONGMASK /* aligned? */
@@ -127,7 +142,7 @@ memset_partial:
EX(LONG_S_L, a1, -1(a0), last_fixup)
#endif
1: jr ra
- move a2, zero
+ nop
small_memset:
beqz a2, 2f
@@ -138,29 +153,29 @@ small_memset:
sb a1, -1(a0)
2: jr ra /* done */
- move a2, zero
- END(memset)
+ nop
+END(__fill_user)
first_fixup:
- jr ra
- nop
+ jr ra
+ move v0, a2
fwd_fixup:
PTR_L t0, TI_TASK($28)
LONG_L t0, THREAD_BUADDR(t0)
- andi a2, 0x3f
- LONG_ADDU a2, t1
+ andi v0, a2, 0x3f
+ LONG_ADDU v0, t1
jr ra
- LONG_SUBU a2, t0
+ LONG_SUBU v0, t0
partial_fixup:
PTR_L t0, TI_TASK($28)
LONG_L t0, THREAD_BUADDR(t0)
- andi a2, LONGMASK
- LONG_ADDU a2, t1
+ andi v0, a2, LONGMASK
+ LONG_ADDU v0, t1
jr ra
- LONG_SUBU a2, t0
+ LONG_SUBU v0, t0
last_fixup:
jr ra
- andi v1, a2, LONGMASK
+ andi v0, a2, LONGMASK
diff --git a/include/asm-mips/string.h b/include/asm-mips/string.h
index 436e3ad..2bba927 100644
--- a/include/asm-mips/string.h
+++ b/include/asm-mips/string.h
@@ -10,6 +10,7 @@
#ifndef _ASM_STRING_H
#define _ASM_STRING_H
+#include <asm/uaccess.h> /* __fill_user() */
/*
* Most of the inline functions are rather naive implementations so I just
@@ -132,7 +133,11 @@ strncmp(__const__ char *__cs, __const__ char *__ct, size_t __count)
#endif /* CONFIG_32BIT */
#define __HAVE_ARCH_MEMSET
-extern void *memset(void *__s, int __c, size_t __count);
+extern inline void *memset(void *s, int c, size_t count)
+{
+ __fill_user(s, c, count);
+ return s;
+}
#define __HAVE_ARCH_MEMCPY
extern void *memcpy(void *__to, __const__ void *__from, size_t __n);
diff --git a/include/asm-mips/uaccess.h b/include/asm-mips/uaccess.h
index c30c718..8c0d226 100644
--- a/include/asm-mips/uaccess.h
+++ b/include/asm-mips/uaccess.h
@@ -11,7 +11,6 @@
#include <linux/kernel.h>
#include <linux/errno.h>
-#include <linux/thread_info.h>
#include <asm-generic/uaccess.h>
/*
@@ -633,23 +632,13 @@ extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n);
* Returns number of bytes that could not be cleared.
* On success, this will be zero.
*/
+extern __kernel_size_t __fill_user(void __user *s, long c, __kernel_size_t n);
+
static inline __kernel_size_t
__clear_user(void __user *addr, __kernel_size_t size)
{
- __kernel_size_t res;
-
might_sleep();
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, $0\n\t"
- "move\t$6, %2\n\t"
- __MODULE_JAL(__bzero)
- "move\t%0, $6"
- : "=r" (res)
- : "r" (addr), "r" (size)
- : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
-
- return res;
+ return __fill_user(addr, 0, size);
}
#define clear_user(addr,n) \
--
1.5.3.4
