[PATCH] Cleanup F00F bug code

This changes the F00F bug workaround code to use the fixmap facilities
instead of touching the page tables directly.  It also removes the
assumption that only 686's don't have the bug.  I have confirmation that
the patch works on buggy pentiums. 

arch/i386/config.in

@@ -41,6 +41,7 @@ if [ "$CONFIG_M386" = "y" ]; then
    define_bool CONFIG_RWSEM_GENERIC_SPINLOCK y
    define_bool CONFIG_RWSEM_XCHGADD_ALGORITHM n
    define_bool CONFIG_X86_PPRO_FENCE y
+   define_bool CONFIG_X86_F00F_BUG y
 else
    define_bool CONFIG_X86_WP_WORKS_OK y
    define_bool CONFIG_X86_INVLPG y
@@ -56,12 +57,14 @@ if [ "$CONFIG_M486" = "y" ]; then
    define_bool CONFIG_X86_USE_STRING_486 y
    define_bool CONFIG_X86_ALIGNMENT_16 y
    define_bool CONFIG_X86_PPRO_FENCE y
+   define_bool CONFIG_X86_F00F_BUG y
 fi
 if [ "$CONFIG_M586" = "y" ]; then
    define_int  CONFIG_X86_L1_CACHE_SHIFT 5
    define_bool CONFIG_X86_USE_STRING_486 y
    define_bool CONFIG_X86_ALIGNMENT_16 y
    define_bool CONFIG_X86_PPRO_FENCE y
+   define_bool CONFIG_X86_F00F_BUG y
 fi
 if [ "$CONFIG_M586TSC" = "y" ]; then
    define_int  CONFIG_X86_L1_CACHE_SHIFT 5
@@ -69,6 +72,7 @@ if [ "$CONFIG_M586TSC" = "y" ]; then
    define_bool CONFIG_X86_ALIGNMENT_16 y
    define_bool CONFIG_X86_TSC y
    define_bool CONFIG_X86_PPRO_FENCE y
+   define_bool CONFIG_X86_F00F_BUG y
 fi
 if [ "$CONFIG_M586MMX" = "y" ]; then
    define_int  CONFIG_X86_L1_CACHE_SHIFT 5
@@ -77,6 +81,7 @@ if [ "$CONFIG_M586MMX" = "y" ]; then
    define_bool CONFIG_X86_TSC y
    define_bool CONFIG_X86_GOOD_APIC y
    define_bool CONFIG_X86_PPRO_FENCE y
+   define_bool CONFIG_X86_F00F_BUG y
 fi
 if [ "$CONFIG_M686" = "y" ]; then
    define_int  CONFIG_X86_L1_CACHE_SHIFT 5

arch/i386/kernel/setup.c

@@ -1961,13 +1961,10 @@ extern void trap_init_f00f_bug(void);
 
 static void __init init_intel(struct cpuinfo_x86 *c)
 {
-#ifndef CONFIG_M686
-	static int f00f_workaround_enabled = 0;
-#endif
 	char *p = NULL;
 	unsigned int l1i = 0, l1d = 0, l2 = 0, l3 = 0; /* Cache sizes */
 
-#ifndef CONFIG_M686
+#ifdef CONFIG_X86_F00F_BUG
 	/*
 	 * All current models of Pentium and Pentium with MMX technology CPUs
 	 * have the F0 0F bug, which lets nonpriviledged users lock up the system.
@@ -1975,6 +1972,8 @@ static void __init init_intel(struct cpuinfo_x86 *c)
 	 */
 	c->f00f_bug = 0;
 	if ( c->x86 == 5 ) {
+		static int f00f_workaround_enabled = 0;
+
 		c->f00f_bug = 1;
 		if ( !f00f_workaround_enabled ) {
 			trap_init_f00f_bug();

arch/i386/kernel/traps.c

@@ -775,35 +775,17 @@ asmlinkage void math_emulate(long arg)
 
 #endif /* CONFIG_MATH_EMULATION */
 
-#ifndef CONFIG_M686
+#ifdef CONFIG_X86_F00F_BUG
 void __init trap_init_f00f_bug(void)
 {
-	unsigned long page;
-	pgd_t * pgd;
-	pmd_t * pmd;
-	pte_t * pte;
-
-	/*
-	 * Allocate a new page in virtual address space, 
-	 * move the IDT into it and write protect this page.
-	 */
-	page = (unsigned long) vmalloc(PAGE_SIZE);
-	pgd = pgd_offset(&init_mm, page);
-	pmd = pmd_offset(pgd, page);
-	pte = pte_offset_kernel(pmd, page);
-	__free_page(pte_page(*pte));
-	*pte = mk_pte_phys(__pa(&idt_table), PAGE_KERNEL_RO);
-	/*
-	 * Not that any PGE-capable kernel should have the f00f bug ...
-	 */
-	__flush_tlb_all();
+	__set_fixmap(FIX_F00F_IDT, __pa(&idt_table), PAGE_KERNEL_RO);
 
 	/*
 	 * "idt" is magic - it overlaps the idt_descr
 	 * variable so that updating idt will automatically
 	 * update the idt descriptor..
 	 */
-	idt = (struct desc_struct *)page;
+	idt = (struct desc_struct *) fix_to_virt(FIX_F00F_IDT);
 	__asm__ __volatile__("lidt %0": "=m" (idt_descr));
 }
 #endif

arch/i386/mm/fault.c

@@ -282,6 +282,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		return;
 	}
 
+#ifdef CONFIG_X86_F00F_BUG
 	/*
 	 * Pentium F0 0F C7 C8 bug workaround.
 	 */
@@ -295,6 +296,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
 			return;
 		}
 	}
+#endif
 
 no_context:
 	/* Are we prepared to handle this kernel fault?  */

include/asm-i386/fixmap.h

@@ -61,6 +61,9 @@ enum fixed_addresses {
 	FIX_LI_PCIA,	/* Lithium PCI Bridge A */
 	FIX_LI_PCIB,	/* Lithium PCI Bridge B */
 #endif
+#ifdef CONFIG_X86_F00F_BUG
+	FIX_F00F_IDT,	/* Virtual mapping for IDT */
+#endif
 #ifdef CONFIG_HIGHMEM
 	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel mappings */
 	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,