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e26a9e00af
virt_to_page() is incredibly inefficient when virt-to-phys patching is
enabled. This is because we end up with this calculation:
page = &mem_map[asm virt_to_phys(addr) >> 12 - __pv_phys_offset >> 12]
in assembly. The asm virt_to_phys() is equivalent this this operation:
addr - PAGE_OFFSET + __pv_phys_offset
and we can see that because this is assembly, the compiler has no chance
to optimise some of that away. This should reduce down to:
page = &mem_map[(addr - PAGE_OFFSET) >> 12]
for the common cases. Permit the compiler to make this optimisation by
giving it more of the information it needs - do this by providing a
virt_to_pfn() macro.
Another issue which makes this more complex is that __pv_phys_offset is
a 64-bit type on all platforms. This is needlessly wasteful - if we
store the physical offset as a PFN, we can save a lot of work having
to deal with 64-bit values, which sometimes ends up producing incredibly
horrid code:
a4c: e3009000 movw r9, #0
a4c: R_ARM_MOVW_ABS_NC __pv_phys_offset
a50: e3409000 movt r9, #0 ; r9 = &__pv_phys_offset
a50: R_ARM_MOVT_ABS __pv_phys_offset
a54: e3002000 movw r2, #0
a54: R_ARM_MOVW_ABS_NC __pv_phys_offset
a58: e3402000 movt r2, #0 ; r2 = &__pv_phys_offset
a58: R_ARM_MOVT_ABS __pv_phys_offset
a5c: e5999004 ldr r9, [r9, #4] ; r9 = high word of __pv_phys_offset
a60: e3001000 movw r1, #0
a60: R_ARM_MOVW_ABS_NC mem_map
a64: e592c000 ldr ip, [r2] ; ip = low word of __pv_phys_offset
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
164 lines
3.9 KiB
C
164 lines
3.9 KiB
C
/*
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* linux/arch/arm/kernel/armksyms.c
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*
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* Copyright (C) 2000 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/string.h>
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#include <linux/cryptohash.h>
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#include <linux/delay.h>
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#include <linux/in6.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <asm/checksum.h>
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#include <asm/ftrace.h>
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/*
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* libgcc functions - functions that are used internally by the
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* compiler... (prototypes are not correct though, but that
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* doesn't really matter since they're not versioned).
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*/
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extern void __ashldi3(void);
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extern void __ashrdi3(void);
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extern void __divsi3(void);
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extern void __lshrdi3(void);
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extern void __modsi3(void);
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extern void __muldi3(void);
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extern void __ucmpdi2(void);
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extern void __udivsi3(void);
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extern void __umodsi3(void);
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extern void __do_div64(void);
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extern void __bswapsi2(void);
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extern void __bswapdi2(void);
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extern void __aeabi_idiv(void);
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extern void __aeabi_idivmod(void);
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extern void __aeabi_lasr(void);
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extern void __aeabi_llsl(void);
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extern void __aeabi_llsr(void);
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extern void __aeabi_lmul(void);
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extern void __aeabi_uidiv(void);
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extern void __aeabi_uidivmod(void);
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extern void __aeabi_ulcmp(void);
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extern void fpundefinstr(void);
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/* platform dependent support */
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EXPORT_SYMBOL(arm_delay_ops);
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/* networking */
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EXPORT_SYMBOL(csum_partial);
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EXPORT_SYMBOL(csum_partial_copy_from_user);
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EXPORT_SYMBOL(csum_partial_copy_nocheck);
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EXPORT_SYMBOL(__csum_ipv6_magic);
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/* io */
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#ifndef __raw_readsb
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EXPORT_SYMBOL(__raw_readsb);
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#endif
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#ifndef __raw_readsw
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EXPORT_SYMBOL(__raw_readsw);
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#endif
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#ifndef __raw_readsl
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EXPORT_SYMBOL(__raw_readsl);
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#endif
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#ifndef __raw_writesb
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EXPORT_SYMBOL(__raw_writesb);
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#endif
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#ifndef __raw_writesw
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EXPORT_SYMBOL(__raw_writesw);
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#endif
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#ifndef __raw_writesl
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EXPORT_SYMBOL(__raw_writesl);
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#endif
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/* string / mem functions */
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EXPORT_SYMBOL(strchr);
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EXPORT_SYMBOL(strrchr);
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EXPORT_SYMBOL(memset);
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EXPORT_SYMBOL(memcpy);
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EXPORT_SYMBOL(memmove);
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EXPORT_SYMBOL(memchr);
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EXPORT_SYMBOL(__memzero);
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#ifdef CONFIG_MMU
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EXPORT_SYMBOL(copy_page);
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EXPORT_SYMBOL(__copy_from_user);
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EXPORT_SYMBOL(__copy_to_user);
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EXPORT_SYMBOL(__clear_user);
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EXPORT_SYMBOL(__get_user_1);
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EXPORT_SYMBOL(__get_user_2);
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EXPORT_SYMBOL(__get_user_4);
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EXPORT_SYMBOL(__put_user_1);
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EXPORT_SYMBOL(__put_user_2);
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EXPORT_SYMBOL(__put_user_4);
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EXPORT_SYMBOL(__put_user_8);
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#endif
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/* gcc lib functions */
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EXPORT_SYMBOL(__ashldi3);
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EXPORT_SYMBOL(__ashrdi3);
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EXPORT_SYMBOL(__divsi3);
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EXPORT_SYMBOL(__lshrdi3);
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EXPORT_SYMBOL(__modsi3);
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EXPORT_SYMBOL(__muldi3);
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EXPORT_SYMBOL(__ucmpdi2);
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EXPORT_SYMBOL(__udivsi3);
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EXPORT_SYMBOL(__umodsi3);
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EXPORT_SYMBOL(__do_div64);
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EXPORT_SYMBOL(__bswapsi2);
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EXPORT_SYMBOL(__bswapdi2);
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#ifdef CONFIG_AEABI
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EXPORT_SYMBOL(__aeabi_idiv);
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EXPORT_SYMBOL(__aeabi_idivmod);
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EXPORT_SYMBOL(__aeabi_lasr);
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EXPORT_SYMBOL(__aeabi_llsl);
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EXPORT_SYMBOL(__aeabi_llsr);
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EXPORT_SYMBOL(__aeabi_lmul);
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EXPORT_SYMBOL(__aeabi_uidiv);
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EXPORT_SYMBOL(__aeabi_uidivmod);
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EXPORT_SYMBOL(__aeabi_ulcmp);
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#endif
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/* bitops */
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EXPORT_SYMBOL(_set_bit);
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EXPORT_SYMBOL(_test_and_set_bit);
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EXPORT_SYMBOL(_clear_bit);
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EXPORT_SYMBOL(_test_and_clear_bit);
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EXPORT_SYMBOL(_change_bit);
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EXPORT_SYMBOL(_test_and_change_bit);
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EXPORT_SYMBOL(_find_first_zero_bit_le);
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EXPORT_SYMBOL(_find_next_zero_bit_le);
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EXPORT_SYMBOL(_find_first_bit_le);
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EXPORT_SYMBOL(_find_next_bit_le);
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#ifdef __ARMEB__
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EXPORT_SYMBOL(_find_first_zero_bit_be);
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EXPORT_SYMBOL(_find_next_zero_bit_be);
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EXPORT_SYMBOL(_find_first_bit_be);
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EXPORT_SYMBOL(_find_next_bit_be);
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#endif
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#ifdef CONFIG_FUNCTION_TRACER
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#ifdef CONFIG_OLD_MCOUNT
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EXPORT_SYMBOL(mcount);
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#endif
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EXPORT_SYMBOL(__gnu_mcount_nc);
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#endif
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#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
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EXPORT_SYMBOL(__pv_phys_pfn_offset);
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EXPORT_SYMBOL(__pv_offset);
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#endif
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