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f548ccd47d
Make the comments a bit clearer for get_bios_ebda so that it actually tells us what it is returning. Signed-off-by: Mike Waychison <mikew@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
61 lines
1.3 KiB
C
61 lines
1.3 KiB
C
#ifndef _ASM_X86_BIOS_EBDA_H
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#define _ASM_X86_BIOS_EBDA_H
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#include <asm/io.h>
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/*
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* Returns physical address of EBDA. Returns 0 if there is no EBDA.
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*/
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static inline unsigned int get_bios_ebda(void)
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{
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/*
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* There is a real-mode segmented pointer pointing to the
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* 4K EBDA area at 0x40E.
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*/
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unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
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address <<= 4;
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return address; /* 0 means none */
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}
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/*
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* Return the sanitized length of the EBDA in bytes, if it exists.
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*/
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static inline unsigned int get_bios_ebda_length(void)
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{
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unsigned int address;
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unsigned int length;
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address = get_bios_ebda();
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if (!address)
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return 0;
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/* EBDA length is byte 0 of the EBDA (stored in KiB) */
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length = *(unsigned char *)phys_to_virt(address);
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length <<= 10;
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/* Trim the length if it extends beyond 640KiB */
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length = min_t(unsigned int, (640 * 1024) - address, length);
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return length;
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}
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void reserve_ebda_region(void);
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#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
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/*
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* This is obviously not a great place for this, but we want to be
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* able to scatter it around anywhere in the kernel.
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*/
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void check_for_bios_corruption(void);
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void start_periodic_check_for_corruption(void);
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#else
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static inline void check_for_bios_corruption(void)
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{
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}
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static inline void start_periodic_check_for_corruption(void)
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{
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}
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#endif
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#endif /* _ASM_X86_BIOS_EBDA_H */
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