[IA64] fix nested_dtlb_miss handler for hugetlb address
The nested_dtlb_miss handler currently does not handle fault from
hugetlb address correctly. It walks the page table assuming PAGE_SIZE.
Thus when taking a fault triggered from hugetlb address, it would not
calculate the pgd/pmd/pte address correctly and thus result an incorrect
invocation of ia64_do_page_fault(). In there, kernel will signal SIGBUS
and application dies (The faulting address is perfectly legal and we
have a valid pte for the corresponding user hugetlb address as well).
This patch fix the described kernel bug. Since nested_dtlb_miss is a
rare event and a slow path anyway, I'm making the change without #ifdef
CONFIG_HUGETLB_PAGE for code readability. Tony, please apply.
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/ivt.S b/arch/ia64/kernel/ivt.S
index d9c05d5..2bc085a 100644
--- a/arch/ia64/kernel/ivt.S
+++ b/arch/ia64/kernel/ivt.S
@@ -405,17 +405,22 @@
* r30: continuation address
* r31: saved pr
*
- * Clobbered: b0, r18, r19, r21, psr.dt (cleared)
+ * Clobbered: b0, r18, r19, r21, r22, psr.dt (cleared)
*/
rsm psr.dt // switch to using physical data addressing
mov r19=IA64_KR(PT_BASE) // get the page table base address
shl r21=r16,3 // shift bit 60 into sign bit
+ mov r18=cr.itir
;;
shr.u r17=r16,61 // get the region number into r17
+ extr.u r18=r18,2,6 // get the faulting page size
;;
cmp.eq p6,p7=5,r17 // is faulting address in region 5?
- shr.u r18=r16,PGDIR_SHIFT // get bits 33-63 of faulting address
+ add r22=-PAGE_SHIFT,r18 // adjustment for hugetlb address
+ add r18=PGDIR_SHIFT-PAGE_SHIFT,r18
;;
+ shr.u r22=r16,r22
+ shr.u r18=r16,r18
(p7) dep r17=r17,r19,(PAGE_SHIFT-3),3 // put region number bits in place
srlz.d
@@ -428,7 +433,7 @@
(p6) dep r17=r18,r19,3,(PAGE_SHIFT-3) // r17=PTA + IFA(33,42)*8
(p7) dep r17=r18,r17,3,(PAGE_SHIFT-6) // r17=PTA + (((IFA(61,63) << 7) | IFA(33,39))*8)
cmp.eq p7,p6=0,r21 // unused address bits all zeroes?
- shr.u r18=r16,PMD_SHIFT // shift L2 index into position
+ shr.u r18=r22,PMD_SHIFT // shift L2 index into position
;;
ld8 r17=[r17] // fetch the L1 entry (may be 0)
;;
@@ -436,7 +441,7 @@
dep r17=r18,r17,3,(PAGE_SHIFT-3) // compute address of L2 page table entry
;;
(p7) ld8 r17=[r17] // fetch the L2 entry (may be 0)
- shr.u r19=r16,PAGE_SHIFT // shift L3 index into position
+ shr.u r19=r22,PAGE_SHIFT // shift L3 index into position
;;
(p7) cmp.eq.or.andcm p6,p7=r17,r0 // was L2 entry NULL?
dep r17=r19,r17,3,(PAGE_SHIFT-3) // compute address of L3 page table entry