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>

1 files changed, 62 insertions, 0 deletions

diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
new file mode 100644
index 000000000000..7e8db53528a7
--- /dev/null
+++ b/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