[PATCH] x86-64: Clean up the early boot page table

- 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>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 28 insertions, 34 deletions

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 118c6088198a..23b45e79a27c 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -13,6 +13,7 @@
 #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>
@@ -260,52 +261,48 @@ 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
@@ -313,12 +310,10 @@ NEXT_PAGE(level3_physmem_pgt)
 #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
@@ -332,12 +327,12 @@ ENTRY(wakeup_level4_pgt)
          */
         .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 c514deb658a3..5a5d43b3ef5d 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -14,7 +14,6 @@
 #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[];