1 files changed, 26 insertions, 15 deletions

diff --git a/arch/x86_64/kernel/head64.c b/arch/x86_64/kernel/head64.c
index 5f197b0a330a..213d90e04755 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)
@@ -29,25 +37,24 @@ static void __init clear_bss(void)
 }
 
 #define NEW_CL_POINTER          0x228   /* Relative to real mode data */
-#define OLD_CL_MAGIC_ADDR       0x90020
+#define OLD_CL_MAGIC_ADDR       0x20
 #define OLD_CL_MAGIC            0xA33F
-#define OLD_CL_BASE_ADDR        0x90000
-#define OLD_CL_OFFSET           0x90022
+#define OLD_CL_OFFSET           0x22
 
 static void __init copy_bootdata(char *real_mode_data)
 {
-        int new_data;
+        unsigned long new_data;
         char * command_line;
 
         memcpy(x86_boot_params, real_mode_data, BOOT_PARAM_SIZE);
-        new_data = *(int *) (x86_boot_params + NEW_CL_POINTER);
+        new_data = *(u32 *) (x86_boot_params + NEW_CL_POINTER);
         if (!new_data) {
-                if (OLD_CL_MAGIC != * (u16 *) OLD_CL_MAGIC_ADDR) {
+                if (OLD_CL_MAGIC != *(u16 *)(real_mode_data + OLD_CL_MAGIC_ADDR)) {
                         return;
                 }
-                new_data = OLD_CL_BASE_ADDR + * (u16 *) OLD_CL_OFFSET;
+                new_data = __pa(real_mode_data) + *(u16 *)(real_mode_data + OLD_CL_OFFSET);
         }
-        command_line = (char *) ((u64)(new_data));
+        command_line = __va(new_data);
         memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 }
 
@@ -55,26 +62,30 @@ void __init x86_64_start_kernel(char * real_mode_data)
 {
         int i;
 
+        /*
+         * Make sure kernel is aligned to 2MB address. Catching it at compile
+         * time is better. Change your config file and compile the kernel
+         * for a 2MB aligned address (CONFIG_PHYSICAL_START)
+         */
+        BUILD_BUG_ON(CONFIG_PHYSICAL_START & (__KERNEL_ALIGN - 1));
+
         /* 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];
 
         pda_init(0);
-        copy_bootdata(real_mode_data);
+        copy_bootdata(__va(real_mode_data));
 #ifdef CONFIG_SMP
         cpu_set(0, cpu_online_map);
 #endif