[xtensa-cvscommit] linux/include/asm-xtensa uaccess.h,1.3,1.4

[<joe...@us...>]

Update of /cvsroot/xtensa/linux/include/asm-xtensa
In directory sc8-pr-cvs1:/tmp/cvs-serv22563/include/asm-xtensa

Modified Files:
	uaccess.h 
Log Message:
Check for user unaligned addresses before trying to access user space.


Index: uaccess.h
===================================================================
RCS file: /cvsroot/xtensa/linux/include/asm-xtensa/uaccess.h,v
retrieving revision 1.3
retrieving revision 1.4
diff -C2 -d -r1.3 -r1.4
*** uaccess.h	12 Jun 2003 23:43:54 -0000	1.3
--- uaccess.h	7 Jul 2003 22:41:59 -0000	1.4
***************
*** 255,277 ****
  	retval = 0;						\
  	switch (size) {						\
! 	  case 1: __put_user_asm(x,ptr,retval,"s8i"); break;	\
! 	  case 2: __put_user_asm(x,ptr,retval,"s16i"); break;	\
! 	  case 4: __put_user_asm(x,ptr,retval,"s32i"); break;	\
! 	  case 8: {						\
  		     __typeof__(*ptr) __v64 = x;		\
  		     retval = __copy_to_user(ptr,&__v64,8);	\
  		     break;					\
! 		  }						\
! 	  default: __put_user_bad();				\
  	}							\
  } while (0)
  
  /*
   * We don't tell gcc that we are accessing memory, but this is OK
   * because we do not write to any memory gcc knows about, so there
   * are no aliasing issues.
   */
! #define __put_user_asm(x, addr, err, insn)	\
     __asm__ __volatile__(			\
  	"1: "insn"  %1, %2, 0		\n"	\
  	"2:				\n"	\
--- 255,315 ----
  	retval = 0;						\
  	switch (size) {						\
!         case 1: __put_user_asm(x,ptr,retval,1,"s8i");  break;	\
!         case 2: __put_user_asm(x,ptr,retval,2,"s16i"); break;   \
!         case 4: __put_user_asm(x,ptr,retval,4,"s32i"); break;   \
!         case 8: {						\
  		     __typeof__(*ptr) __v64 = x;		\
  		     retval = __copy_to_user(ptr,&__v64,8);	\
  		     break;					\
! 	        }						\
! 	default: __put_user_bad();				\
  	}							\
  } while (0)
  
+ 
+ /* Consider a case of a user single load/store would cause both an
+  * unaligned exception and an MMU-related exception (unaligned
+  * exceptions happen first):
+  *
+  * User code passes a bad variable ptr to a system call.
+  * Kernel tries to access the variable.
+  * Unaligned exception occurs.
+  * Unaligned exception handler tries to make aligned accesses.
+  * Double exception occurs for MMU-related cause (e.g., page not mapped).
+  * do_page_fault() thinks the fault address belongs to the kernel, not the user, and panics.
+  *
+  * The kernel currently prohibits user unaligned accesses.  We use the
+  * __check_align_* macros to check for unaligned addresses before
+  * accessing user space so we don't crash the kernel.  Both
+  * __put_user_asm and __get_user_asm use these alignment macros, so
+  * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
+  * sync.
+  */
+ 
+ #define __check_align_1  ""
+ 
+ #define __check_align_2				\
+ 	"   _bbci.l %2,  0, 1f		\n"	\
+ 	"   movi    %0, %3		\n"	\
+ 	"   _j      2f			\n"
+ 
+ #define __check_align_4				\
+ 	"   _bbsi.l %2,  0, 0f		\n"	\
+ 	"   _bbci.l %2,  1, 1f		\n"	\
+ 	"0: movi    %0, %3		\n"	\
+ 	"   _j      2f			\n"
+ 
+ 
  /*
   * We don't tell gcc that we are accessing memory, but this is OK
   * because we do not write to any memory gcc knows about, so there
   * are no aliasing issues.
+  *
+  * WARNING: If you modify this macro at all, verify that the
+  * __check_align_* macros still work.
   */
! #define __put_user_asm(x, addr, err, align, insn) \
     __asm__ __volatile__(			\
+ 	__check_align_##align			\
  	"1: "insn"  %1, %2, 0		\n"	\
  	"2:				\n"	\
***************
*** 291,295 ****
  	:"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
  
- 
  #define __get_user_nocheck(x,ptr,size)				\
  ({								\
--- 329,332 ----
***************
*** 312,329 ****
  extern long __get_user_bad(void);
  
! #define __get_user_size(x,ptr,size,retval)			\
! do {								\
! 	retval = 0;						\
! 	switch (size) {						\
! 	  case 1: __get_user_asm(x,ptr,retval,"l8ui"); break;	\
! 	  case 2: __get_user_asm(x,ptr,retval,"l16ui"); break;	\
! 	  case 4: __get_user_asm(x,ptr,retval,"l32i"); break;	\
! 	  case 8: retval = __copy_from_user(&x,ptr,8); break;	\
! 	  default: (x) = __get_user_bad();			\
! 	}							\
  } while (0)
  
! #define __get_user_asm(x, addr, err, insn)	\
     __asm__ __volatile__(			\
  	"1: "insn"  %1, %2, 0		\n"	\
  	"2:				\n"	\
--- 349,372 ----
  extern long __get_user_bad(void);
  
! #define __get_user_size(x,ptr,size,retval)				\
! do {									\
! 	retval = 0;							\
!         switch (size) {							\
!           case 1: __get_user_asm(x,ptr,retval,1,"l8ui");  break;	\
!           case 2: __get_user_asm(x,ptr,retval,2,"l16ui"); break;	\
!           case 4: __get_user_asm(x,ptr,retval,4,"l32i");  break;	\
!           case 8: retval = __copy_from_user(&x,ptr,8);    break;	\
!           default: (x) = __get_user_bad();				\
!         }								\
  } while (0)
  
! 
! /*
!  * WARNING: If you modify this macro at all, verify that the
!  * __check_align_* macros still work.
!  */
! #define __get_user_asm(x, addr, err, align, insn) \
     __asm__ __volatile__(			\
+ 	__check_align_##align			\
  	"1: "insn"  %1, %2, 0		\n"	\
  	"2:				\n"	\