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paravirt/x86, 64-bit: move __PAGE_OFFSET to leave a space for hypervisor

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Set __PAGE_OFFSET to the most negative possible address +
16*PGDIR_SIZE.  The gap is to allow a space for a hypervisor to fit.
The gap is more or less arbitrary, but it's what Xen needs.

When booting native, kernel/head_64.S has a set of compile-time
generated pagetables used at boot time.  This patch removes their
absolutely hard-coded layout, and makes it parameterised on
__PAGE_OFFSET (and __START_KERNEL_map).

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Eduardo Habkost 2008-06-25 00:19:16 -04:00 committed by Ingo Molnar
parent 491eccb721
commit a6523748bd
2 changed files with 19 additions and 6 deletions
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17
arch/x86/kernel/head_64.S
View file

@ -32,6 +32,13 @@
* *
*/ */
#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
L4_PAGE_OFFSET = pgd_index(__PAGE_OFFSET)
L3_PAGE_OFFSET = pud_index(__PAGE_OFFSET)
L4_START_KERNEL = pgd_index(__START_KERNEL_map)
L3_START_KERNEL = pud_index(__START_KERNEL_map)
.text .text
.section .text.head .section .text.head
.code64 .code64
@ -77,8 +84,8 @@ startup_64:
/* Fixup the physical addresses in the page table /* Fixup the physical addresses in the page table
*/ */
addq %rbp, init_level4_pgt + 0(%rip) addq %rbp, init_level4_pgt + 0(%rip)
addq %rbp, init_level4_pgt + (258*8)(%rip) addq %rbp, init_level4_pgt + (L4_PAGE_OFFSET*8)(%rip)
addq %rbp, init_level4_pgt + (511*8)(%rip) addq %rbp, init_level4_pgt + (L4_START_KERNEL*8)(%rip)
addq %rbp, level3_ident_pgt + 0(%rip) addq %rbp, level3_ident_pgt + 0(%rip)
@ -338,9 +345,9 @@ ENTRY(name)
*/ */
NEXT_PAGE(init_level4_pgt) NEXT_PAGE(init_level4_pgt)
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 257,8,0 .org init_level4_pgt + L4_PAGE_OFFSET*8, 0
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 252,8,0 .org init_level4_pgt + L4_START_KERNEL*8, 0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
@ -349,7 +356,7 @@ NEXT_PAGE(level3_ident_pgt)
.fill 511,8,0 .fill 511,8,0
NEXT_PAGE(level3_kernel_pgt) NEXT_PAGE(level3_kernel_pgt)
.fill 510,8,0 .fill L3_START_KERNEL,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */ /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
.quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE

8
include/asm-x86/page_64.h
View file

@ -26,7 +26,13 @@
#define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT) #define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT)
#define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1)) #define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1))
#define __PAGE_OFFSET _AC(0xffff810000000000, UL) /*
* Set __PAGE_OFFSET to the most negative possible address +
* PGDIR_SIZE*16 (pgd slot 272). The gap is to allow a space for a
* hypervisor to fit. Choosing 16 slots here is arbitrary, but it's
* what Xen requires.
*/
#define __PAGE_OFFSET _AC(0xffff880000000000, UL)
#define __PHYSICAL_START CONFIG_PHYSICAL_START #define __PHYSICAL_START CONFIG_PHYSICAL_START
#define __KERNEL_ALIGN 0x200000 #define __KERNEL_ALIGN 0x200000