[xtensa-cvscommit] linux/arch/xtensa/kernel handlers.S,1.4,1.5

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

Update of /cvsroot/xtensa/linux/arch/xtensa/kernel
In directory usw-pr-cvs1:/tmp/cvs-serv11036/arch/xtensa/kernel

Modified Files:
	handlers.S 
Log Message:


The 2nd-level miss handlers overlooked a rare case where current->mm might be NULL and they should use current->active_mm instead.  See the inline comments for details.

This fixes the board crash manifested by 'apachectl stop'.


Index: handlers.S
===================================================================
RCS file: /cvsroot/xtensa/linux/arch/xtensa/kernel/handlers.S,v
retrieving revision 1.4
retrieving revision 1.5
diff -C2 -d -r1.4 -r1.5
*** handlers.S	22 Sep 2002 21:18:02 -0000	1.4
--- handlers.S	22 Oct 2002 17:59:43 -0000	1.5
***************
*** 1996,1999 ****
--- 1996,2000 ----
  	   {
  	   	struct task_struct *tsk = current;
+ 		struct mm_struct *mm = tsk->mm;
  	   	unsigned long vpnval;
  	   	pgd_t *pgd;
***************
*** 2012,2033 ****
  	movi	a2, kernelsp
  	s32i	a3, a0, MISS_SAVE_A3
- 	l32i	a2, a2, 0		// a2 <-- kernel sp
  	s32i	a4, a0, MISS_SAVE_A4
  	s32i	a5, a0, MISS_SAVE_A5
  
! 	/* We need to map the page of PTEs for the user task.  Find
!          * the pointer to that page.
  
! 	   pgd = pgd_offset (tsk->mm, regs->excvaddr);
  	   pmd = pmd_offset (pgd, regs->excvaddr);
- 	*/
  
! 	srli  a2, a2, _CURRENT_SHIFT
! 	slli  a2, a2, _CURRENT_SHIFT	// a2 <-- 'current' or 'tsk'
! 	rsr	a3, EXCVADDR
! 	l32i	a2, a2, TASK_MM
  	_PGD_OFFSET   a2, a3
  	_PMD_OFFSET   a2, addr	// empty macro, 2nd parm is optimized away
! 	
  	/* We want to map the page of PTEs into the Page Table, but if
           * the task doesn't yet have a mapping for the region, just
--- 2013,2045 ----
  	movi	a2, kernelsp
  	s32i	a3, a0, MISS_SAVE_A3
  	s32i	a4, a0, MISS_SAVE_A4
+ 	l32i	a4, a2, 0		// a4 <-- kernel sp
  	s32i	a5, a0, MISS_SAVE_A5
  
! 	/*  We need to map the page of PTEs for the user task.  Find *
! 	 * the pointer to that page.  Also, it's possible for tsk->mm
! 	 * to be NULL while tsk->active_mm is nonzero if we faulted on
! 	 * a vmalloc address.  In that rare case, we must use
! 	 * active_mm instead to avoid a fault in this handler.  See
! 	 *
! 	 * http://mail.nl.linux.org/linux-mm/2002-08/msg00258.html
! 	 *   (or search Internet on "mm vs. active_mm")
  
! 	   if (!mm)
! 		   mm = tsk->active_mm;
! 	   pgd = pgd_offset (mm, regs->excvaddr);
  	   pmd = pmd_offset (pgd, regs->excvaddr);
  
! 	 */
! 
! 	srli	a4, a4, _CURRENT_SHIFT
! 	slli	a4, a4, _CURRENT_SHIFT	// a4 <-- 'current' or 'tsk'
! 	rsr	a3, EXCVADDR		// a3 <-- fault address
! 	l32i	a2, a4, TASK_MM		// a2 <-- tsk->mm
! 	beqz	a2, vmalloc_case	// branch on rare vmalloc case
! 4:
  	_PGD_OFFSET   a2, a3
  	_PMD_OFFSET   a2, addr	// empty macro, 2nd parm is optimized away
! 
  	/* We want to map the page of PTEs into the Page Table, but if
           * the task doesn't yet have a mapping for the region, just
***************
*** 2106,2109 ****
--- 2118,2125 ----
  	xsr	a1, EXCSAVE_1
  	rfde
+ 
+ vmalloc_case:
+ 	l32i	a2, a4, TASK_ACTIVE_MM	// a2 <-- tsk->active_mm
+ 	j	4b