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![Ashish Kalra](/assets/img/avatar_default.png)
The minimum size for a new stack (512 bytes) setup for arch/x86/boot components when the bootloader does not setup/provide a stack for the early boot components is not "enough". The setup code executing as part of early kernel startup code, uses the stack beyond 512 bytes and accidentally overwrites and corrupts part of the BSS section. This is exposed mostly in the early video setup code, where it was corrupting BSS variables like force_x, force_y, which in-turn affected kernel parameters such as screen_info (screen_info.orig_video_cols) and later caused an exception/panic in console_init(). Most recent boot loaders setup the stack for early boot components, so this stack overwriting into BSS section issue has not been exposed. Signed-off-by: Ashish Kalra <ashish@bluestacks.com> Cc: <stable@vger.kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170419152015.10011-1-ashishkalra@Ashishs-MacBook-Pro.local Signed-off-by: Ingo Molnar <mingo@kernel.org>
358 lines
7.9 KiB
C
358 lines
7.9 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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* Copyright 2009 Intel Corporation; author H. Peter Anvin
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* Header file for the real-mode kernel code
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*/
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#ifndef BOOT_BOOT_H
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#define BOOT_BOOT_H
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#define STACK_SIZE 1024 /* Minimum number of bytes for stack */
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#ifndef __ASSEMBLY__
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#include <stdarg.h>
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#include <linux/types.h>
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#include <linux/edd.h>
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#include <asm/setup.h>
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#include <asm/asm.h>
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#include "bitops.h"
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#include "ctype.h"
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#include "cpuflags.h"
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/* Useful macros */
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#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
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extern struct setup_header hdr;
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extern struct boot_params boot_params;
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#define cpu_relax() asm volatile("rep; nop")
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/* Basic port I/O */
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static inline void outb(u8 v, u16 port)
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{
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asm volatile("outb %0,%1" : : "a" (v), "dN" (port));
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}
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static inline u8 inb(u16 port)
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{
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u8 v;
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asm volatile("inb %1,%0" : "=a" (v) : "dN" (port));
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return v;
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}
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static inline void outw(u16 v, u16 port)
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{
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asm volatile("outw %0,%1" : : "a" (v), "dN" (port));
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}
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static inline u16 inw(u16 port)
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{
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u16 v;
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asm volatile("inw %1,%0" : "=a" (v) : "dN" (port));
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return v;
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}
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static inline void outl(u32 v, u16 port)
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{
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asm volatile("outl %0,%1" : : "a" (v), "dN" (port));
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}
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static inline u32 inl(u16 port)
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{
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u32 v;
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asm volatile("inl %1,%0" : "=a" (v) : "dN" (port));
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return v;
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}
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static inline void io_delay(void)
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{
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const u16 DELAY_PORT = 0x80;
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asm volatile("outb %%al,%0" : : "dN" (DELAY_PORT));
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}
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/* These functions are used to reference data in other segments. */
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static inline u16 ds(void)
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{
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u16 seg;
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asm("movw %%ds,%0" : "=rm" (seg));
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return seg;
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}
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static inline void set_fs(u16 seg)
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{
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asm volatile("movw %0,%%fs" : : "rm" (seg));
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}
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static inline u16 fs(void)
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{
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u16 seg;
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asm volatile("movw %%fs,%0" : "=rm" (seg));
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return seg;
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}
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static inline void set_gs(u16 seg)
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{
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asm volatile("movw %0,%%gs" : : "rm" (seg));
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}
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static inline u16 gs(void)
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{
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u16 seg;
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asm volatile("movw %%gs,%0" : "=rm" (seg));
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return seg;
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}
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typedef unsigned int addr_t;
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static inline u8 rdfs8(addr_t addr)
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{
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u8 v;
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asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr));
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return v;
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}
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static inline u16 rdfs16(addr_t addr)
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{
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u16 v;
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asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr));
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return v;
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}
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static inline u32 rdfs32(addr_t addr)
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{
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u32 v;
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asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr));
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return v;
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}
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static inline void wrfs8(u8 v, addr_t addr)
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{
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asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v));
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}
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static inline void wrfs16(u16 v, addr_t addr)
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{
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asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v));
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}
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static inline void wrfs32(u32 v, addr_t addr)
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{
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asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v));
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}
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static inline u8 rdgs8(addr_t addr)
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{
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u8 v;
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asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr));
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return v;
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}
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static inline u16 rdgs16(addr_t addr)
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{
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u16 v;
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asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr));
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return v;
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}
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static inline u32 rdgs32(addr_t addr)
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{
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u32 v;
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asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr));
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return v;
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}
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static inline void wrgs8(u8 v, addr_t addr)
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{
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asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v));
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}
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static inline void wrgs16(u16 v, addr_t addr)
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{
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asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v));
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}
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static inline void wrgs32(u32 v, addr_t addr)
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{
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asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v));
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}
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/* Note: these only return true/false, not a signed return value! */
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static inline bool memcmp_fs(const void *s1, addr_t s2, size_t len)
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{
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bool diff;
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asm volatile("fs; repe; cmpsb" CC_SET(nz)
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: CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
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return diff;
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}
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static inline bool memcmp_gs(const void *s1, addr_t s2, size_t len)
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{
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bool diff;
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asm volatile("gs; repe; cmpsb" CC_SET(nz)
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: CC_OUT(nz) (diff), "+D" (s1), "+S" (s2), "+c" (len));
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return diff;
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}
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/* Heap -- available for dynamic lists. */
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extern char _end[];
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extern char *HEAP;
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extern char *heap_end;
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#define RESET_HEAP() ((void *)( HEAP = _end ))
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static inline char *__get_heap(size_t s, size_t a, size_t n)
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{
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char *tmp;
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HEAP = (char *)(((size_t)HEAP+(a-1)) & ~(a-1));
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tmp = HEAP;
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HEAP += s*n;
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return tmp;
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}
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#define GET_HEAP(type, n) \
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((type *)__get_heap(sizeof(type),__alignof__(type),(n)))
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static inline bool heap_free(size_t n)
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{
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return (int)(heap_end-HEAP) >= (int)n;
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}
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/* copy.S */
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void copy_to_fs(addr_t dst, void *src, size_t len);
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void *copy_from_fs(void *dst, addr_t src, size_t len);
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void copy_to_gs(addr_t dst, void *src, size_t len);
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void *copy_from_gs(void *dst, addr_t src, size_t len);
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/* a20.c */
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int enable_a20(void);
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/* apm.c */
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int query_apm_bios(void);
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/* bioscall.c */
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struct biosregs {
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union {
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struct {
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u32 edi;
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u32 esi;
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u32 ebp;
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u32 _esp;
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u32 ebx;
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u32 edx;
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u32 ecx;
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u32 eax;
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u32 _fsgs;
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u32 _dses;
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u32 eflags;
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};
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struct {
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u16 di, hdi;
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u16 si, hsi;
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u16 bp, hbp;
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u16 _sp, _hsp;
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u16 bx, hbx;
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u16 dx, hdx;
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u16 cx, hcx;
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u16 ax, hax;
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u16 gs, fs;
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u16 es, ds;
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u16 flags, hflags;
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};
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struct {
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u8 dil, dih, edi2, edi3;
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u8 sil, sih, esi2, esi3;
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u8 bpl, bph, ebp2, ebp3;
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u8 _spl, _sph, _esp2, _esp3;
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u8 bl, bh, ebx2, ebx3;
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u8 dl, dh, edx2, edx3;
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u8 cl, ch, ecx2, ecx3;
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u8 al, ah, eax2, eax3;
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};
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};
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};
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void intcall(u8 int_no, const struct biosregs *ireg, struct biosregs *oreg);
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/* cmdline.c */
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int __cmdline_find_option(unsigned long cmdline_ptr, const char *option, char *buffer, int bufsize);
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int __cmdline_find_option_bool(unsigned long cmdline_ptr, const char *option);
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static inline int cmdline_find_option(const char *option, char *buffer, int bufsize)
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{
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unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
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if (cmd_line_ptr >= 0x100000)
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return -1; /* inaccessible */
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return __cmdline_find_option(cmd_line_ptr, option, buffer, bufsize);
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}
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static inline int cmdline_find_option_bool(const char *option)
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{
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unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
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if (cmd_line_ptr >= 0x100000)
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return -1; /* inaccessible */
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return __cmdline_find_option_bool(cmd_line_ptr, option);
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}
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/* cpu.c, cpucheck.c */
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int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr);
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int check_knl_erratum(void);
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int validate_cpu(void);
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/* early_serial_console.c */
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extern int early_serial_base;
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void console_init(void);
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/* edd.c */
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void query_edd(void);
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/* header.S */
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void __attribute__((noreturn)) die(void);
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/* memory.c */
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int detect_memory(void);
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/* pm.c */
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void __attribute__((noreturn)) go_to_protected_mode(void);
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/* pmjump.S */
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void __attribute__((noreturn))
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protected_mode_jump(u32 entrypoint, u32 bootparams);
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/* printf.c */
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int sprintf(char *buf, const char *fmt, ...);
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int vsprintf(char *buf, const char *fmt, va_list args);
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int printf(const char *fmt, ...);
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/* regs.c */
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void initregs(struct biosregs *regs);
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/* string.c */
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int strcmp(const char *str1, const char *str2);
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int strncmp(const char *cs, const char *ct, size_t count);
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size_t strnlen(const char *s, size_t maxlen);
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unsigned int atou(const char *s);
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unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base);
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size_t strlen(const char *s);
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char *strchr(const char *s, int c);
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/* tty.c */
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void puts(const char *);
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void putchar(int);
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int getchar(void);
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void kbd_flush(void);
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int getchar_timeout(void);
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/* video.c */
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void set_video(void);
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/* video-mode.c */
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int set_mode(u16 mode);
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int mode_defined(u16 mode);
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void probe_cards(int unsafe);
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/* video-vesa.c */
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void vesa_store_edid(void);
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#endif /* __ASSEMBLY__ */
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#endif /* BOOT_BOOT_H */
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