x86: add is_errata100 helper to fault_32|64.c

Further towards unifying these files, add another helper
in same spirit as is_errata93.

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, 19 insertions, 0 deletions

diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
index 75ae8c498d67..0bd241729aa3 100644
--- a/arch/x86/mm/fault_32.c
+++ b/arch/x86/mm/fault_32.c
@@ -286,6 +286,22 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
         return 0;
 }
 
+/*
+ * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
+ * addresses >4GB.  We catch this in the page fault handler because these
+ * addresses are not reachable. Just detect this case and return.  Any code
+ * segment in LDT is compatibility mode.
+ */
+static int is_errata100(struct pt_regs *regs, unsigned long address)
+{
+#ifdef CONFIG_X86_64
+        if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
+            (address >> 32))
+                return 1;
+#endif
+        return 0;
+}
+
 void do_invalid_op(struct pt_regs *, unsigned long);
 
 static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
@@ -566,6 +582,9 @@ bad_area_nosemaphore:
                 if (is_prefetch(regs, address, error_code))
                         return;
 
+                if (is_errata100(regs, address))
+                        return;
+
                 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
                     printk_ratelimit()) {
                         printk(