x86: unify extable_{32|64}.c

Introduce fixup_exception() on 64-bit and use it in kprobes to
eliminate an #ifdef.

Only 64-bit needs search_extable() due to a stepping bug.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/kprobes.c

@@ -904,19 +904,9 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 		 * In case the user-specified fault handler returned
 		 * zero, try to fix up.
 		 */
-#ifdef CONFIG_X86_64
-		{
-			const struct exception_table_entry *fixup;
-			fixup = search_exception_tables(regs->ip);
-			if (fixup) {
-				regs->ip = fixup->fixup;
-				return 1;
-			}
-		}
-#else
 		if (fixup_exception(regs))
 			return 1;
-#endif
+
 		/*
 		 * fixup routine could not handle it,
 		 * Let do_page_fault() fix it.

arch/x86/mm/Makefile_32

@@ -2,7 +2,7 @@
 # Makefile for the linux i386-specific parts of the memory manager.
 #
 
-obj-y	:= init_32.o pgtable_32.o fault_32.o ioremap_32.o extable_32.o pageattr_32.o mmap.o
+obj-y	:= init_32.o pgtable_32.o fault_32.o ioremap_32.o extable.o pageattr_32.o mmap.o
 
 obj-$(CONFIG_NUMA) += discontig_32.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o

arch/x86/mm/Makefile_64

@@ -2,7 +2,7 @@
 # Makefile for the linux x86_64-specific parts of the memory manager.
 #
 
-obj-y	 := init_64.o fault_64.o ioremap_64.o extable_64.o pageattr_64.o mmap.o
+obj-y	 := init_64.o fault_64.o ioremap_64.o extable.o pageattr_64.o mmap.o
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_NUMA) += numa_64.o
 obj-$(CONFIG_K8_NUMA) += k8topology_64.o

arch/x86/mm/extable.c

@@ -0,0 +1,62 @@
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <asm/uaccess.h>
+
+
+int fixup_exception(struct pt_regs *regs)
+{
+	const struct exception_table_entry *fixup;
+
+#ifdef CONFIG_PNPBIOS
+	if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
+		extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
+		extern u32 pnp_bios_is_utter_crap;
+		pnp_bios_is_utter_crap = 1;
+		printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
+		__asm__ volatile(
+			"movl %0, %%esp\n\t"
+			"jmp *%1\n\t"
+			: : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
+		panic("do_trap: can't hit this");
+	}
+#endif
+
+	fixup = search_exception_tables(regs->ip);
+	if (fixup) {
+		regs->ip = fixup->fixup;
+		return 1;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * Need to defined our own search_extable on X86_64 to work around
+ * a B stepping K8 bug.
+ */
+const struct exception_table_entry *
+search_extable(const struct exception_table_entry *first,
+	       const struct exception_table_entry *last,
+	       unsigned long value)
+{
+	/* B stepping K8 bug */
+	if ((value >> 32) == 0)
+		value |= 0xffffffffUL << 32;
+
+	while (first <= last) {
+		const struct exception_table_entry *mid;
+		long diff;
+
+		mid = (last - first) / 2 + first;
+		diff = mid->insn - value;
+		if (diff == 0)
+			return mid;
+		else if (diff < 0)
+			first = mid+1;
+		else
+			last = mid-1;
+	}
+	return NULL;
+}
+#endif