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| author | Eduardo Habkost <ehabkost@redhat.com> | 2008-06-25 00:19:16 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-08 13:11:04 +0200 |
| commit | a6523748bddd38bcec11431f57502090b6014a96 (patch) | |
| tree | 1aa906ba270628323fcdfb26a0ae0f7cfba80ae6 | |
| parent | 491eccb721c2ee67250273a96e4515fb5b423337 (diff) | |
| download | linux-3.10-a6523748bddd38bcec11431f57502090b6014a96.tar.gz linux-3.10-a6523748bddd38bcec11431f57502090b6014a96.tar.bz2 linux-3.10-a6523748bddd38bcec11431f57502090b6014a96.zip | |
paravirt/x86, 64-bit: move __PAGE_OFFSET to leave a space for hypervisor
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>
| -rw-r--r-- | arch/x86/kernel/head_64.S | 17 | ||||
| -rw-r--r-- | include/asm-x86/page_64.h | 8 |
2 files changed, 19 insertions, 6 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 32f5a114d1a..38279fab093 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -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 .section .text.head .code64 @@ -77,8 +84,8 @@ startup_64: /* Fixup the physical addresses in the page table */ addq %rbp, init_level4_pgt + 0(%rip) - addq %rbp, init_level4_pgt + (258*8)(%rip) - addq %rbp, init_level4_pgt + (511*8)(%rip) + addq %rbp, init_level4_pgt + (L4_PAGE_OFFSET*8)(%rip) + addq %rbp, init_level4_pgt + (L4_START_KERNEL*8)(%rip) addq %rbp, level3_ident_pgt + 0(%rip) @@ -338,9 +345,9 @@ ENTRY(name) */ NEXT_PAGE(init_level4_pgt) .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 - .fill 252,8,0 + .org init_level4_pgt + L4_START_KERNEL*8, 0 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */ .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE @@ -349,7 +356,7 @@ NEXT_PAGE(level3_ident_pgt) .fill 511,8,0 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 */ .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE .quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE diff --git a/include/asm-x86/page_64.h b/include/asm-x86/page_64.h index cac5b9e7826..010d12db80d 100644 --- a/include/asm-x86/page_64.h +++ b/include/asm-x86/page_64.h @@ -26,7 +26,13 @@ #define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT) #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 __KERNEL_ALIGN 0x200000 |