Introduce __fill_user() and kill __bzero() [take #3]
PATCH 1/1 Introduce __fill_user() and kill __bzero() [take #3]
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. This patch also renames memset.S into fill_user.S as suggested by Thiemo.
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. It has been put into a new file called string.c.
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 <[email protected]>
---
Ralf,
Since you use git, this patch has been generated with rename detection enabled. It makes the review a lot easier.
Please consider,
Franck
arch/mips/kernel/mips_ksyms.c | 2 +-
arch/mips/lib/Makefile | 4 +-
arch/mips/lib/csum_partial.S | 2 +-
arch/mips/lib/{memset.S => fill_user.S} | 34 +++++++++++++++---------------
arch/mips/lib/memcpy.S | 2 +-
arch/mips/lib/string.c | 13 +++++++++++
include/asm-mips/string.h | 7 +++++-
include/asm-mips/uaccess.h | 17 ++------------
8 files changed, 44 insertions(+), 37 deletions(-)
rename arch/mips/lib/{memset.S => fill_user.S} (90%)
create mode 100644 arch/mips/lib/string.carch/mips/kernel/mips_ksyms.c +1 -1
@@ -38,7 +38,7 @@ EXPORT_SYMBOL(kernel_thread);*/ EXPORT_SYMBOL (__copy_user);EXPORT_SYMBOL (__copy_user_inatomic); -EXPORT_SYMBOL (__bzero); +EXPORT_SYMBOL (__fill_user);EXPORT_SYMBOL (__strncpy_from_user_nocheck_asm);EXPORT_SYMBOL (__strncpy_from_user_asm);EXPORT_SYMBOL (__strlen_user_nocheck_asm);
arch/mips/lib/Makefile +2 -2
@@ -2,8 +2,8 @@ # Makefile for MIPS-specific library files.. # -lib-y += csum_partial.o memcpy.o memcpy-inatomic.o memset.o strlen_user.o \ - strncpy_user.o strnlen_user.o uncached.o +lib-y += csum_partial.o fill_user.o memcpy.o memcpy-inatomic.o string.o \ + strlen_user.o strncpy_user.o strnlen_user.o uncached.o obj-y += iomap.o obj-$(CONFIG_PCI) += iomap-pci.o
arch/mips/lib/csum_partial.S +1 -1
@@ -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
arch/mips/lib/fill_user.S renamed from arch/mips/lib/memset.S +17 -17
@@ -46,17 +46,19 @@ .endm /* - * memset(void *s, int c, size_t n) + * __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 +70,6 @@ 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 +127,7 @@ 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 +138,29 @@ 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
arch/mips/lib/memcpy.S +1 -1
@@ -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
arch/mips/lib/string.c new file +13 -0
@@ -0,0 +1,13 @@ +#include <linux/kernel.h> + +#include <asm/uaccess.h> + +/* +* An outline version of memset, which should be used either by gcc or +* by assembly code. +*/ +void *memset (void *s,int c,__kernel_size_t len) +{ +__fill_user (s, c, len); +return s; +}
include/asm-mips/string.h +6 -1
@@ -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);
include/asm-mips/uaccess.h +3 -14
@@ -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) \
Signature · 1 line
1.5.3.5