7 files changed, 25 insertions, 61 deletions

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 926aa2197aaa..c211e52f1333 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -71,7 +71,7 @@ startup_32:
         movl    %eax, %cr4
 
         /* Setup early boot stage 4 level pagetables */
-        movl    $(boot_level4_pgt - __START_KERNEL_map), %eax
+        movl    $(init_level4_pgt - __START_KERNEL_map), %eax
         movl    %eax, %cr3
 
         /* Setup EFER (Extended Feature Enable Register) */
@@ -115,7 +115,7 @@ ENTRY(secondary_startup_64)
         movq    %rax, %cr4
 
         /* Setup early boot stage 4 level pagetables. */
-        movq    $(boot_level4_pgt - __START_KERNEL_map), %rax
+        movq    $(init_level4_pgt - __START_KERNEL_map), %rax
         movq    %rax, %cr3
 
         /* Check if nx is implemented */
@@ -274,9 +274,19 @@ ENTRY(name)
         i = i + 1 ;                             \
         .endr
 
+        /*
+         * This default setting generates an ident mapping at address 0x100000
+         * and a mapping for the kernel that precisely maps virtual address
+         * 0xffffffff80000000 to physical address 0x000000. (always using
+         * 2Mbyte large pages provided by PAE mode)
+         */
 NEXT_PAGE(init_level4_pgt)
-        /* This gets initialized in x86_64_start_kernel */
-        .fill   512,8,0
+        .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   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
 
 NEXT_PAGE(level3_ident_pgt)
         .quad   level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
@@ -307,27 +317,6 @@ NEXT_PAGE(level2_kernel_pgt)
 #undef NEXT_PAGE
 
         .data
-
-#ifndef CONFIG_HOTPLUG_CPU
-        __INITDATA
-#endif
-        /*
-         * This default setting generates an ident mapping at address 0x100000
-         * and a mapping for the kernel that precisely maps virtual address
-         * 0xffffffff80000000 to physical address 0x000000. (always using
-         * 2Mbyte large pages provided by PAE mode)
-         */
-        .align PAGE_SIZE
-ENTRY(boot_level4_pgt)
-        .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   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
-
-        .data
-
         .align 16
         .globl cpu_gdt_descr
 cpu_gdt_descr:
diff --git a/arch/x86_64/kernel/head64.c b/arch/x86_64/kernel/head64.c
index 5c529c1e3d6c..6c34bdd22e26 100644
--- a/arch/x86_64/kernel/head64.c
+++ b/arch/x86_64/kernel/head64.c
@@ -18,8 +18,16 @@
 #include <asm/setup.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
+#include <asm/tlbflush.h>
 #include <asm/sections.h>
 
+static void __init zap_identity_mappings(void)
+{
+        pgd_t *pgd = pgd_offset_k(0UL);
+        pgd_clear(pgd);
+        __flush_tlb();
+}
+
 /* Don't add a printk in there. printk relies on the PDA which is not initialized 
    yet. */
 static void __init clear_bss(void)
@@ -57,18 +65,15 @@ void __init x86_64_start_kernel(char * real_mode_data)
         /* clear bss before set_intr_gate with early_idt_handler */
         clear_bss();
 
+        /* Make NULL pointers segfault */
+        zap_identity_mappings();
+
         for (i = 0; i < IDT_ENTRIES; i++)
                 set_intr_gate(i, early_idt_handler);
         asm volatile("lidt %0" :: "m" (idt_descr));
 
         early_printk("Kernel alive\n");
 
-        /*
-         * switch to init_level4_pgt from boot_level4_pgt
-         */
-        memcpy(init_level4_pgt, boot_level4_pgt, PTRS_PER_PGD*sizeof(pgd_t));
-        asm volatile("movq %0,%%cr3" :: "r" (__pa_symbol(&init_level4_pgt)));
-
         for (i = 0; i < NR_CPUS; i++)
                 cpu_pda(i) = &boot_cpu_pda[i];
 
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 65e2bc551a2b..0e2b8df0ea64 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -274,8 +274,6 @@ void __init setup_arch(char **cmdline_p)
 
         dmi_scan_machine();
 
-        zap_low_mappings(0);
-
 #ifdef CONFIG_ACPI
         /*
          * Initialize the ACPI boot-time table parser (gets the RSDP and SDT).
diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c
index 6a70b55f719d..53064a9a365f 100644
--- a/arch/x86_64/kernel/setup64.c
+++ b/arch/x86_64/kernel/setup64.c
@@ -201,7 +201,6 @@ void __cpuinit cpu_init (void)
         /* CPU 0 is initialised in head64.c */
         if (cpu != 0) {
                 pda_init(cpu);
-                zap_low_mappings(cpu);
         } else 
                 estacks = boot_exception_stacks; 
 
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 4ab3d40aac90..b0a607892183 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -378,21 +378,6 @@ void __meminit init_memory_mapping(unsigned long start, unsigned long end)
         __flush_tlb_all();
 }
 
-void __cpuinit zap_low_mappings(int cpu)
-{
-        if (cpu == 0) {
-                pgd_t *pgd = pgd_offset_k(0UL);
-                pgd_clear(pgd);
-        } else {
-                /*
-                 * For AP's, zap the low identity mappings by changing the cr3
-                 * to init_level4_pgt and doing local flush tlb all
-                 */
-                asm volatile("movq %0,%%cr3" :: "r" (__pa_symbol(&init_level4_pgt)));
-        }
-        __flush_tlb_all();
-}
-
 #ifndef CONFIG_NUMA
 void __init paging_init(void)
 {
@@ -569,15 +554,6 @@ void __init mem_init(void)
                 reservedpages << (PAGE_SHIFT-10),
                 datasize >> 10,
                 initsize >> 10);
-
-#ifdef CONFIG_SMP
-        /*
-         * Sync boot_level4_pgt mappings with the init_level4_pgt
-         * except for the low identity mappings which are already zapped
-         * in init_level4_pgt. This sync-up is essential for AP's bringup
-         */
-        memcpy(boot_level4_pgt+1, init_level4_pgt+1, (PTRS_PER_PGD-1)*sizeof(pgd_t));
-#endif
 }
 
 void free_init_pages(char *what, unsigned long begin, unsigned long end)
diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 5a5d43b3ef5d..703f0243f27a 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -17,7 +17,6 @@ extern pud_t level3_kernel_pgt[512];
 extern pud_t level3_ident_pgt[512];
 extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
-extern pgd_t boot_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
 #define swapper_pg_dir init_level4_pgt
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index 78427021d94a..3f8f285138d2 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -11,8 +11,6 @@ struct pt_regs;
 extern void start_kernel(void);
 extern void pda_init(int); 
 
-extern void zap_low_mappings(int cpu);
-
 extern void early_idt_handler(void);
 
 extern void mcheck_init(struct cpuinfo_x86 *c);