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authorEduardo Habkost <ehabkost@redhat.com>2008-06-25 00:19:16 -0400
committerIngo Molnar <mingo@elte.hu>2008-07-08 13:11:04 +0200
commita6523748bddd38bcec11431f57502090b6014a96 (patch)
tree1aa906ba270628323fcdfb26a0ae0f7cfba80ae6
parent491eccb721c2ee67250273a96e4515fb5b423337 (diff)
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.S17
-rw-r--r--include/asm-x86/page_64.h8
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