x86/mm: Expand the exception table logic to allow new handling options

[firefly-linux-kernel-4.4.55.git] / arch / x86 / include / asm / uaccess.h

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 09b1b0ab94b7653f7ed7019eb7e35b518582f825..3794c7331cfc72b36343e512a5089b1500984451 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -90,12 +90,11 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
        likely(!__range_not_ok(addr, size, user_addr_max()))
 
 /*
- * The exception table consists of pairs of addresses relative to the
- * exception table enty itself: the first is the address of an
- * instruction that is allowed to fault, and the second is the address
- * at which the program should continue.  No registers are modified,
- * so it is entirely up to the continuation code to figure out what to
- * do.
+ * The exception table consists of triples of addresses relative to the
+ * exception table entry itself. The first address is of an instruction
+ * that is allowed to fault, the second is the target at which the program
+ * should continue. The third is a handler function to deal with the fault
+ * caused by the instruction in the first field.
  *
  * All the routines below use bits of fixup code that are out of line
  * with the main instruction path.  This means when everything is well,
@@ -104,13 +103,14 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
  */
 
 struct exception_table_entry {
-       int insn, fixup;
+       int insn, fixup, handler;
 };
 /* This is not the generic standard exception_table_entry format */
 #define ARCH_HAS_SORT_EXTABLE
 #define ARCH_HAS_SEARCH_EXTABLE
 
-extern int fixup_exception(struct pt_regs *regs);
+extern int fixup_exception(struct pt_regs *regs, int trapnr);
+extern bool ex_has_fault_handler(unsigned long ip);
 extern int early_fixup_exception(unsigned long *ip);
 
 /*
@@ -394,7 +394,11 @@ do {                                                                       \
 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                        \
        asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
                     "2:\n"                                             \
-                    _ASM_EXTABLE_EX(1b, 2b)                            \
+                    ".section .fixup,\"ax\"\n"                         \
+                     "3:xor"itype" %"rtype"0,%"rtype"0\n"              \
+                    "  jmp 2b\n"                                       \
+                    ".previous\n"                                      \
+                    _ASM_EXTABLE_EX(1b, 3b)                            \
                     : ltype(x) : "m" (__m(addr)))
 
 #define __put_user_nocheck(x, ptr, size)                       \