x86-32, mm: Add an initial page table for core bootstrapping

This patch adds an initial page table with low mappings used exclusively
for booting APs/resuming after ACPI suspend/machine restart. After this,
there's no need to add low mappings to swapper_pg_dir and zap them later
or create own swsusp PGD page solely for ACPI sleep needs - we have
initial_page_table for that.

Signed-off-by: Borislav Petkov <bp@alien8.de>
LKML-Reference: <20101020070526.GA9588@liondog.tnic>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

11 files changed, 56 insertions, 119 deletions

diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pgtable_32.h
index f686f49e8b7b..8abde9ec90bf 100644
--- a/arch/x86/include/asm/pgtable_32.h
+++ b/arch/x86/include/asm/pgtable_32.h
@@ -26,7 +26,7 @@ struct mm_struct;
 struct vm_area_struct;
 
 extern pgd_t swapper_pg_dir[1024];
-extern pgd_t trampoline_pg_dir[1024];
+extern pgd_t initial_page_table[1024];
 
 static inline void pgtable_cache_init(void) { }
 static inline void check_pgt_cache(void) { }
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 7f3eba08e7de..169be8938b96 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -172,6 +172,4 @@ static inline void flush_tlb_kernel_range(unsigned long start,
         flush_tlb_all();
 }
 
-extern void zap_low_mappings(bool early);
-
 #endif /* _ASM_X86_TLBFLUSH_H */
diff --git a/arch/x86/include/asm/trampoline.h b/arch/x86/include/asm/trampoline.h
index 4dde797c0578..f4500fb3b485 100644
--- a/arch/x86/include/asm/trampoline.h
+++ b/arch/x86/include/asm/trampoline.h
@@ -13,16 +13,13 @@ extern unsigned char *trampoline_base;
 
 extern unsigned long init_rsp;
 extern unsigned long initial_code;
-extern unsigned long initial_page_table;
 extern unsigned long initial_gs;
 
 #define TRAMPOLINE_SIZE roundup(trampoline_end - trampoline_data, PAGE_SIZE)
 
 extern unsigned long setup_trampoline(void);
-extern void __init setup_trampoline_page_table(void);
 extern void __init reserve_trampoline_memory(void);
 #else
-static inline void setup_trampoline_page_table(void) {}
 static inline void reserve_trampoline_memory(void) {}
 #endif /* CONFIG_X86_TRAMPOLINE */
 
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 33cec152070d..b35e1ab8ba03 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -12,6 +12,11 @@
 #include <asm/segment.h>
 #include <asm/desc.h>
 
+#ifdef CONFIG_X86_32
+#include <asm/pgtable.h>
+#include <asm/pgtable_32.h>
+#endif
+
 #include "realmode/wakeup.h"
 #include "sleep.h"
 
@@ -90,7 +95,7 @@ int acpi_save_state_mem(void)
 
 #ifndef CONFIG_64BIT
         header->pmode_entry = (u32)&wakeup_pmode_return;
-        header->pmode_cr3 = (u32)(swsusp_pg_dir - __PAGE_OFFSET);
+        header->pmode_cr3 = (u32)__pa(&initial_page_table);
         saved_magic = 0x12345678;
 #else /* CONFIG_64BIT */
         header->trampoline_segment = setup_trampoline() >> 4;
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 784360c0625c..8b9c2019fc0e 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -17,6 +17,7 @@
 #include <asm/apic.h>
 #include <asm/io_apic.h>
 #include <asm/bios_ebda.h>
+#include <asm/tlbflush.h>
 
 static void __init i386_default_early_setup(void)
 {
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index fa8c1b8e09fb..bcece91dd311 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -183,13 +183,12 @@ default_entry:
 #ifdef CONFIG_X86_PAE
 
         /*
-         * In PAE mode swapper_pg_dir is statically defined to contain enough
-         * entries to cover the VMSPLIT option (that is the top 1, 2 or 3
-         * entries). The identity mapping is handled by pointing two PGD
-         * entries to the first kernel PMD.
+         * In PAE mode initial_page_table is statically defined to contain
+         * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
+         * entries). The identity mapping is handled by pointing two PGD entries
+         * to the first kernel PMD.
          *
-         * Note the upper half of each PMD or PTE are always zero at
-         * this stage.
+         * Note the upper half of each PMD or PTE are always zero at this stage.
          */
 
 #define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
@@ -197,7 +196,7 @@ default_entry:
         xorl %ebx,%ebx                          /* %ebx is kept at zero */
 
         movl $pa(__brk_base), %edi
-        movl $pa(swapper_pg_pmd), %edx
+        movl $pa(initial_pg_pmd), %edx
         movl $PTE_IDENT_ATTR, %eax
 10:
         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PMD entry */
@@ -226,14 +225,14 @@ default_entry:
         movl %eax, pa(max_pfn_mapped)
 
         /* Do early initialization of the fixmap area */
-        movl $pa(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
-        movl %eax,pa(swapper_pg_pmd+0x1000*KPMDS-8)
+        movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
+        movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
 #else   /* Not PAE */
 
 page_pde_offset = (__PAGE_OFFSET >> 20);
 
         movl $pa(__brk_base), %edi
-        movl $pa(swapper_pg_dir), %edx
+        movl $pa(initial_page_table), %edx
         movl $PTE_IDENT_ATTR, %eax
 10:
         leal PDE_IDENT_ATTR(%edi),%ecx          /* Create PDE entry */
@@ -257,8 +256,8 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
         movl %eax, pa(max_pfn_mapped)
 
         /* Do early initialization of the fixmap area */
-        movl $pa(swapper_pg_fixmap)+PDE_IDENT_ATTR,%eax
-        movl %eax,pa(swapper_pg_dir+0xffc)
+        movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
+        movl %eax,pa(initial_page_table+0xffc)
 #endif
         jmp 3f
 /*
@@ -334,7 +333,7 @@ ENTRY(startup_32_smp)
 /*
  * Enable paging
  */
-        movl pa(initial_page_table), %eax
+        movl $pa(initial_page_table), %eax
         movl %eax,%cr3          /* set the page table pointer.. */
         movl %cr0,%eax
         orl  $X86_CR0_PG,%eax
@@ -614,8 +613,6 @@ ignore_int:
 .align 4
 ENTRY(initial_code)
         .long i386_start_kernel