x86, extable: Add early_fixup_exception()

Add a restricted version of fixup_exception() to be used during early
boot only.  In particular, this doesn't support the try..catch variant
since we may not have a thread_info set up yet.

This relies on the exception table being sorted already at build time.

Link: http://lkml.kernel.org/r/1334794610-5546-1-git-send-email-hpa@zytor.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 1fb85dbe390ab7a1810c88ff5e60ee4f380bb93a..5555675dadb6d4a2fd02b42c0cd5ffb97206da71 100644 (file)
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -35,3 +35,20 @@ int fixup_exception(struct pt_regs *regs)
 
        return 0;
 }
+
+/* Restricted version used during very early boot */
+int __init early_fixup_exception(unsigned long *ip)
+{
+       const struct exception_table_entry *fixup;
+
+       fixup = search_exception_tables(*ip);
+       if (fixup) {
+               if (fixup->fixup < 16)
+                       return 0; /* Not supported during early boot */
+
+               *ip = fixup->fixup;
+               return 1;
+       }
+
+       return 0;
+}