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[PATCH] x86: make __FIXADDR_TOP variable to allow it to make space for a hypervisor

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Make __FIXADDR_TOP a variable, so that it can be set to not get in the way of
address space a hypervisor may want to reserve.

Original patch by Gerd Hoffmann <kraxel@suse.de>

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeremy Fitzhardinge 2006-09-25 23:32:25 -07:00 committed by Linus Torvalds
parent 9f093394d7
commit 052e79941a
4 changed files with 75 additions and 1 deletions
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1
arch/i386/Kconfig
View file

@ -794,6 +794,7 @@ config HOTPLUG_CPU
config COMPAT_VDSO
bool "Compat VDSO support"
default y
depends on !PARAVIRT
help
Map the VDSO to the predictable old-style address too.
---help---

42
arch/i386/mm/init.c
View file

@ -629,6 +629,48 @@ void __init mem_init(void)
(unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
);
#if 1 /* double-sanity-check paranoia */
printk("virtual kernel memory layout:\n"
" fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n"
#ifdef CONFIG_HIGHMEM
" pkmap : 0x%08lx - 0x%08lx (%4ld kB)\n"
#endif
" vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n"
" lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n"
" .init : 0x%08lx - 0x%08lx (%4ld kB)\n"
" .data : 0x%08lx - 0x%08lx (%4ld kB)\n"
" .text : 0x%08lx - 0x%08lx (%4ld kB)\n",
FIXADDR_START, FIXADDR_TOP,
(FIXADDR_TOP - FIXADDR_START) >> 10,
#ifdef CONFIG_HIGHMEM
PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
(LAST_PKMAP*PAGE_SIZE) >> 10,
#endif
VMALLOC_START, VMALLOC_END,
(VMALLOC_END - VMALLOC_START) >> 20,
(unsigned long)__va(0), (unsigned long)high_memory,
((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,
(unsigned long)&__init_begin, (unsigned long)&__init_end,
((unsigned long)&__init_end - (unsigned long)&__init_begin) >> 10,
(unsigned long)&_etext, (unsigned long)&_edata,
((unsigned long)&_edata - (unsigned long)&_etext) >> 10,
(unsigned long)&_text, (unsigned long)&_etext,
((unsigned long)&_etext - (unsigned long)&_text) >> 10);
#ifdef CONFIG_HIGHMEM
BUG_ON(PKMAP_BASE+LAST_PKMAP*PAGE_SIZE > FIXADDR_START);
BUG_ON(VMALLOC_END > PKMAP_BASE);
#endif
BUG_ON(VMALLOC_START > VMALLOC_END);
BUG_ON((unsigned long)high_memory > VMALLOC_START);
#endif /* double-sanity-check paranoia */
#ifdef CONFIG_X86_PAE
if (!cpu_has_pae)
panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");

26
arch/i386/mm/pgtable.c
View file

@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/system.h>
#include <asm/pgtable.h>
@ -139,6 +140,12 @@ void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
__flush_tlb_one(vaddr);
}
static int fixmaps;
#ifndef CONFIG_COMPAT_VDSO
unsigned long __FIXADDR_TOP = 0xfffff000;
EXPORT_SYMBOL(__FIXADDR_TOP);
#endif
void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
{
unsigned long address = __fix_to_virt(idx);
@ -148,6 +155,25 @@ void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
return;
}
set_pte_pfn(address, phys >> PAGE_SHIFT, flags);
fixmaps++;
}
/**
* reserve_top_address - reserves a hole in the top of kernel address space
* @reserve - size of hole to reserve
*
* Can be used to relocate the fixmap area and poke a hole in the top
* of kernel address space to make room for a hypervisor.
*/
void reserve_top_address(unsigned long reserve)
{
BUG_ON(fixmaps > 0);
#ifdef CONFIG_COMPAT_VDSO
BUG_ON(reserve != 0);
#else
__FIXADDR_TOP = -reserve - PAGE_SIZE;
__VMALLOC_RESERVE += reserve;
#endif
}
pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)

7
include/asm-i386/fixmap.h
View file

@ -19,7 +19,11 @@
* Leave one empty page between vmalloc'ed areas and
* the start of the fixmap.
*/
#define __FIXADDR_TOP 0xfffff000
#ifndef CONFIG_COMPAT_VDSO
extern unsigned long __FIXADDR_TOP;
#else
#define __FIXADDR_TOP 0xfffff000
#endif
#ifndef __ASSEMBLY__
#include <linux/kernel.h>
@ -93,6 +97,7 @@ enum fixed_addresses {
extern void __set_fixmap (enum fixed_addresses idx,
unsigned long phys, pgprot_t flags);
extern void reserve_top_address(unsigned long reserve);
#define set_fixmap(idx, phys) \
__set_fixmap(idx, phys, PAGE_KERNEL)