[PATCH 19/33] x86_64: Cleanup the early boot page table.

Eric W. Biederman
2006-08-01T11:06:59Z

- Merge physmem_pgt and ident_pgt, removing physmem_pgt. The merge
is broken as soon as mm/init.c:init_memory_mapping is run.
- As physmem_pgt is gone don't export it in pgtable.h.
- Use defines from pgtable.h for page permissions.
- Fix the physical memory identity mapping so it is at the correct
address.
- Remove the physical memory mapping from wakeup_level4_pgt it
is at the wrong address so we can't possibly be usinging it.
- Simply NEXT_PAGE the work to calculate the phys_ alias
of the labels was very cool. Unfortuantely it was a brittle
special purpose hack that makes maitenance more difficult.
Instead just use label - __START_KERNEL_map like we do
everywhere else in assembly.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
arch/x86_64/kernel/head.S | 61 +++++++++++++++++++-----------------------
include/asm-x86_64/pgtable.h | 1 -
2 files changed, 28 insertions(+), 34 deletions(-)

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index ca57a37..a9e34d9 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -15,6 +15,7 @@ #include <linux/threads.h>
#include <linux/init.h>
#include <asm/desc.h>
#include <asm/segment.h>
+#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/msr.h>
#include <asm/cache.h>
@@ -250,52 +251,48 @@ ljumpvector:
ENTRY(stext)
ENTRY(_stext)

- $page = 0
#define NEXT_PAGE(name) \
- $page = $page + 1; \
- .org $page * 0x1000; \
- phys_/**/name = $page * 0x1000 + __PHYSICAL_START; \
+ .balign PAGE_SIZE; \
ENTRY(name)

+/* Automate the creation of 1 to 1 mapping pmd entries */
+#define PMDS(START, PERM, COUNT) \
+ i = 0 ; \
+ .rept (COUNT) ; \
+ .quad (START) + (i << 21) + (PERM) ; \
+ i = i + 1 ; \
+ .endr
+
NEXT_PAGE(init_level4_pgt)
/* This gets initialized in x86_64_start_kernel */
.fill 512,8,0

NEXT_PAGE(level3_ident_pgt)
- .quad phys_level2_ident_pgt | 0x007
+ .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 511,8,0

NEXT_PAGE(level3_kernel_pgt)
.fill 510,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
- .quad phys_level2_kernel_pgt | 0x007
+ .quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
.fill 1,8,0

NEXT_PAGE(level2_ident_pgt)
- /* 40MB for bootup. */
- i = 0
- .rept 20
- .quad i << 21 | 0x083
- i = i + 1
- .endr
- .fill 492,8,0
+ /* Since I easily can, map the first 1G.
+ * Don't set NX because code runs from these pages.
+ */
+ PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD)

NEXT_PAGE(level2_kernel_pgt)
/* 40MB kernel mapping. The kernel code cannot be bigger than that.
When you change this change KERNEL_TEXT_SIZE in page.h too. */
/* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */
- i = 0
- .rept 20
- .quad i << 21 | 0x183
- i = i + 1
- .endr
+ PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL,
+ KERNEL_TEXT_SIZE/PMD_SIZE)
/* Module mapping starts here */
- .fill 492,8,0
-
-NEXT_PAGE(level3_physmem_pgt)
- .quad phys_level2_kernel_pgt | 0x007 /* so that __va works even before pagetable_init */
- .fill 511,8,0
+ .fill (PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0

+#undef PMDS
#undef NEXT_PAGE

.data
@@ -303,12 +300,10 @@ #undef NEXT_PAGE
#ifdef CONFIG_ACPI_SLEEP
.align PAGE_SIZE
ENTRY(wakeup_level4_pgt)
- .quad phys_level3_ident_pgt | 0x007
- .fill 255,8,0
- .quad phys_level3_physmem_pgt | 0x007
- .fill 254,8,0
+ .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+ .fill 510,8,0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
- .quad phys_level3_kernel_pgt | 0x007
+ .quad level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
#endif

#ifndef CONFIG_HOTPLUG_CPU
@@ -322,12 +317,12 @@ #endif
*/
.align PAGE_SIZE
ENTRY(boot_level4_pgt)
- .quad phys_level3_ident_pgt | 0x007
- .fill 255,8,0
- .quad phys_level3_physmem_pgt | 0x007
- .fill 254,8,0
+ .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+ .fill 257,8,0
+ .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+ .fill 252,8,0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
- .quad phys_level3_kernel_pgt | 0x007
+ .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE

.data

diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 211a2ca..5528e8b 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -15,7 +15,6 @@ #include <linux/threads.h>
#include <asm/pda.h>

extern pud_t level3_kernel_pgt[512];
-extern pud_t level3_physmem_pgt[512];
extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
extern pgd_t init_level4_pgt[];
--
1.4.2.rc2.g5209e