x86, extable: Add _ASM_EXTABLE_EX() macro

Add _ASM_EXTABLE_EX() to generate the special extable entries that are
associated with uaccess_err.  This allows us to change the protocol
associated with these special entries.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/CA%2B55aFyijf43qSu3N9nWHEBwaGbb7T2Oq9A=9EyR=Jtyqfq_cQ@mail.gmail.com

2 files changed, 24 insertions, 12 deletions

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 53dce41f2517..0f15e8a4f565 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -40,16 +40,28 @@
 
 /* Exception table entry */
 #ifdef __ASSEMBLY__
-# define _ASM_EXTABLE(from,to)                  \
-        .pushsection "__ex_table","a" ;         \
-        _ASM_ALIGN ;                            \
-        _ASM_PTR from , to ;                    \
+# define _ASM_EXTABLE(from,to)                                  \
+        .pushsection "__ex_table","a" ;                         \
+        _ASM_ALIGN ;                                            \
+        _ASM_PTR from , to ;                                    \
+        .popsection
+
+# define _ASM_EXTABLE_EX(from,to)                               \
+        .pushsection "__ex_table","a" ;                         \
+        _ASM_ALIGN ;                                            \
+        _ASM_PTR from , (to) - (from) ;                         \
         .popsection
 #else
-# define _ASM_EXTABLE(from,to)                  \
-        " .pushsection \"__ex_table\",\"a\"\n"  \
-        _ASM_ALIGN "\n"                         \
-        _ASM_PTR #from "," #to "\n"             \
+# define _ASM_EXTABLE(from,to)                                  \
+        " .pushsection \"__ex_table\",\"a\"\n"                  \
+        _ASM_ALIGN "\n"                                         \
+        _ASM_PTR #from "," #to "\n"                             \
+        " .popsection\n"
+
+# define _ASM_EXTABLE_EX(from,to)                               \
+        " .pushsection \"__ex_table\",\"a\"\n"                  \
+        _ASM_ALIGN "\n"                                         \
+        _ASM_PTR #from ",(" #to ")-(" #from ")\n"               \
         " .popsection\n"
 #endif
 
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index e0544597cfe7..4ee59dd66f5d 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -202,8 +202,8 @@ extern int __get_user_bad(void);
         asm volatile("1:        movl %%eax,0(%1)\n"                     \
                      "2:        movl %%edx,4(%1)\n"                     \
                      "3:\n"                                             \
-                     _ASM_EXTABLE(1b, 2b - 1b)                          \
-                     _ASM_EXTABLE(2b, 3b - 2b)                          \
+                     _ASM_EXTABLE_EX(1b, 2b)                            \
+                     _ASM_EXTABLE_EX(2b, 3b)                            \
                      : : "A" (x), "r" (addr))
 
 #define __put_user_x8(x, ptr, __ret_pu)                         \
@@ -408,7 +408,7 @@ do {									\
 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
                      "2:\n"                                             \
-                     _ASM_EXTABLE(1b, 2b - 1b)                          \
+                     _ASM_EXTABLE_EX(1b, 2b)                            \
                      : ltype(x) : "m" (__m(addr)))
 
 #define __put_user_nocheck(x, ptr, size)                        \
@@ -450,7 +450,7 @@ struct __large_struct { unsigned long buf[100]; };
 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
                      "2:\n"                                             \
-                     _ASM_EXTABLE(1b, 2b - 1b)                          \
+                     _ASM_EXTABLE_EX(1b, 2b)                            \
                      : : ltype(x), "m" (__m(addr)))
 
 /*