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alistair23-linux/arch/arm/kernel/armksyms.c
Nicolas Pitre ff5fdafc9e ARM: 8745/1: get rid of __memzero() 
The __memzero assembly code is almost identical to memset's except for
two orr instructions. The runtime performance of __memset(p, n) and
memset(p, 0, n) is accordingly almost identical.

However, the memset() macro used to guard against a zero length and to
call __memzero at compile time when the fill value is a constant zero
interferes with compiler optimizations.

Arnd found tha the test against a zero length brings up some new
warnings with gcc v8:

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82103

And successively rremoving the test against a zero length and the call
to __memzero optimization produces the following kernel sizes for
defconfig with gcc 6:

    text     data     bss       dec       hex  filename
12248142  6278960  413588  18940690   1210312  vmlinux.orig
12244474  6278960  413588  18937022   120f4be  vmlinux.no_zero_test
12239160  6278960  413588  18931708   120dffc  vmlinux.no_memzero

So it is probably not worth keeping __memzero around given that the
compiler can do a better job at inlining trivial memset(p,0,n) on its
own. And the memset code already handles a zero length just fine.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-01-21 15:37:56 +00:00

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/*
* linux/arch/arm/kernel/armksyms.c
*
* Copyright (C) 2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/cryptohash.h>
#include <linux/delay.h>
#include <linux/in6.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/arm-smccc.h>
#include <asm/checksum.h>
#include <asm/ftrace.h>
/*
* libgcc functions - functions that are used internally by the
* compiler... (prototypes are not correct though, but that
* doesn't really matter since they're not versioned).
*/
extern void __ashldi3(void);
extern void __ashrdi3(void);
extern void __divsi3(void);
extern void __lshrdi3(void);
extern void __modsi3(void);
extern void __muldi3(void);
extern void __ucmpdi2(void);
extern void __udivsi3(void);
extern void __umodsi3(void);
extern void __do_div64(void);
extern void __bswapsi2(void);
extern void __bswapdi2(void);
extern void __aeabi_idiv(void);
extern void __aeabi_idivmod(void);
extern void __aeabi_lasr(void);
extern void __aeabi_llsl(void);
extern void __aeabi_llsr(void);
extern void __aeabi_lmul(void);
extern void __aeabi_uidiv(void);
extern void __aeabi_uidivmod(void);
extern void __aeabi_ulcmp(void);
extern void fpundefinstr(void);
void mmioset(void *, unsigned int, size_t);
void mmiocpy(void *, const void *, size_t);
/* platform dependent support */
EXPORT_SYMBOL(arm_delay_ops);
/* networking */
EXPORT_SYMBOL(csum_partial);
EXPORT_SYMBOL(csum_partial_copy_from_user);
EXPORT_SYMBOL(csum_partial_copy_nocheck);
EXPORT_SYMBOL(__csum_ipv6_magic);
/* io */
#ifndef __raw_readsb
EXPORT_SYMBOL(__raw_readsb);
#endif
#ifndef __raw_readsw
EXPORT_SYMBOL(__raw_readsw);
#endif
#ifndef __raw_readsl
EXPORT_SYMBOL(__raw_readsl);
#endif
#ifndef __raw_writesb
EXPORT_SYMBOL(__raw_writesb);
#endif
#ifndef __raw_writesw
EXPORT_SYMBOL(__raw_writesw);
#endif
#ifndef __raw_writesl
EXPORT_SYMBOL(__raw_writesl);
#endif
/* string / mem functions */
EXPORT_SYMBOL(strchr);
EXPORT_SYMBOL(strrchr);
EXPORT_SYMBOL(memset);
EXPORT_SYMBOL(__memset32);
EXPORT_SYMBOL(__memset64);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memchr);
EXPORT_SYMBOL(mmioset);
EXPORT_SYMBOL(mmiocpy);
#ifdef CONFIG_MMU
EXPORT_SYMBOL(copy_page);
EXPORT_SYMBOL(arm_copy_from_user);
EXPORT_SYMBOL(arm_copy_to_user);
EXPORT_SYMBOL(arm_clear_user);
EXPORT_SYMBOL(__get_user_1);
EXPORT_SYMBOL(__get_user_2);
EXPORT_SYMBOL(__get_user_4);
EXPORT_SYMBOL(__get_user_8);
#ifdef __ARMEB__
EXPORT_SYMBOL(__get_user_64t_1);
EXPORT_SYMBOL(__get_user_64t_2);
EXPORT_SYMBOL(__get_user_64t_4);
EXPORT_SYMBOL(__get_user_32t_8);
#endif
EXPORT_SYMBOL(__put_user_1);
EXPORT_SYMBOL(__put_user_2);
EXPORT_SYMBOL(__put_user_4);
EXPORT_SYMBOL(__put_user_8);
#endif
/* gcc lib functions */
EXPORT_SYMBOL(__ashldi3);
EXPORT_SYMBOL(__ashrdi3);
EXPORT_SYMBOL(__divsi3);
EXPORT_SYMBOL(__lshrdi3);
EXPORT_SYMBOL(__modsi3);
EXPORT_SYMBOL(__muldi3);
EXPORT_SYMBOL(__ucmpdi2);
EXPORT_SYMBOL(__udivsi3);
EXPORT_SYMBOL(__umodsi3);
EXPORT_SYMBOL(__do_div64);
EXPORT_SYMBOL(__bswapsi2);
EXPORT_SYMBOL(__bswapdi2);
#ifdef CONFIG_AEABI
EXPORT_SYMBOL(__aeabi_idiv);
EXPORT_SYMBOL(__aeabi_idivmod);
EXPORT_SYMBOL(__aeabi_lasr);
EXPORT_SYMBOL(__aeabi_llsl);
EXPORT_SYMBOL(__aeabi_llsr);
EXPORT_SYMBOL(__aeabi_lmul);
EXPORT_SYMBOL(__aeabi_uidiv);
EXPORT_SYMBOL(__aeabi_uidivmod);
EXPORT_SYMBOL(__aeabi_ulcmp);
#endif
/* bitops */
EXPORT_SYMBOL(_set_bit);
EXPORT_SYMBOL(_test_and_set_bit);
EXPORT_SYMBOL(_clear_bit);
EXPORT_SYMBOL(_test_and_clear_bit);
EXPORT_SYMBOL(_change_bit);
EXPORT_SYMBOL(_test_and_change_bit);
EXPORT_SYMBOL(_find_first_zero_bit_le);
EXPORT_SYMBOL(_find_next_zero_bit_le);
EXPORT_SYMBOL(_find_first_bit_le);
EXPORT_SYMBOL(_find_next_bit_le);
#ifdef __ARMEB__
EXPORT_SYMBOL(_find_first_zero_bit_be);
EXPORT_SYMBOL(_find_next_zero_bit_be);
EXPORT_SYMBOL(_find_first_bit_be);
EXPORT_SYMBOL(_find_next_bit_be);
#endif
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_OLD_MCOUNT
EXPORT_SYMBOL(mcount);
#endif
EXPORT_SYMBOL(__gnu_mcount_nc);
#endif
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
EXPORT_SYMBOL(__pv_phys_pfn_offset);
EXPORT_SYMBOL(__pv_offset);
#endif
#ifdef CONFIG_HAVE_ARM_SMCCC
EXPORT_SYMBOL(__arm_smccc_smc);
EXPORT_SYMBOL(__arm_smccc_hvc);
#endif
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