[57/65] parisc: fix SMP races when updating PTE and TLB entries in entry.S

From: Steven Rostedt
Date: Mon Jun 03 2013 - 18:32:34 EST

3.6.11.5 stable review patch.
If anyone has any objections, please let me know.

------------------

From: John David Anglin <dave.anglin@xxxxxxxx>

[ Upstream commit f0a18819e261afc5fdbd8c5c6f9943123c5461ba ]

Currently, race conditions exist in the handling of TLB interruptions in
entry.S. In particular, dirty bit updates can be lost if an accessed
interruption occurs just after the dirty bit interruption on a different
cpu. Lost dirty bit updates result in user pages not being flushed and
general system instability. This change adds lock and unlock macros to
synchronize all PTE and TLB updates done in entry.S. As a result,
userspace stability is significantly improved.

Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
arch/parisc/kernel/entry.S | 155 ++++++++++++++++++++++++--------------------
1 file changed, 83 insertions(+), 72 deletions(-)

diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index 38a4998..1818c65 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -444,9 +444,41 @@
L2_ptep \pgd,\pte,\index,\va,\fault
.endm

+ /* Acquire pa_dbit_lock lock. */
+ .macro dbit_lock spc,tmp,tmp1
+#ifdef CONFIG_SMP
+ cmpib,COND(=),n 0,\spc,2f
+ load32 PA(pa_dbit_lock),\tmp
+1: LDCW 0(\tmp),\tmp1
+ cmpib,COND(=) 0,\tmp1,1b
+ nop
+2:
+#endif
+ .endm
+
+ /* Release pa_dbit_lock lock without reloading lock address. */
+ .macro dbit_unlock0 spc,tmp
+#ifdef CONFIG_SMP
+ or,COND(=) %r0,\spc,%r0
+ stw \spc,0(\tmp)
+#endif
+ .endm
+
+ /* Release pa_dbit_lock lock. */
+ .macro dbit_unlock1 spc,tmp
+#ifdef CONFIG_SMP
+ load32 PA(pa_dbit_lock),\tmp
+ dbit_unlock0 \spc,\tmp
+#endif
+ .endm
+
/* Set the _PAGE_ACCESSED bit of the PTE. Be clever and
* don't needlessly dirty the cache line if it was already set */
- .macro update_ptep ptep,pte,tmp,tmp1
+ .macro update_ptep spc,ptep,pte,tmp,tmp1
+#ifdef CONFIG_SMP
+ or,COND(=) %r0,\spc,%r0
+ LDREG 0(\ptep),\pte
+#endif
ldi _PAGE_ACCESSED,\tmp1
or \tmp1,\pte,\tmp
and,COND(<>) \tmp1,\pte,%r0
@@ -455,7 +487,11 @@

/* Set the dirty bit (and accessed bit). No need to be
* clever, this is only used from the dirty fault */
- .macro update_dirty ptep,pte,tmp
+ .macro update_dirty spc,ptep,pte,tmp
+#ifdef CONFIG_SMP
+ or,COND(=) %r0,\spc,%r0
+ LDREG 0(\ptep),\pte
+#endif
ldi _PAGE_ACCESSED|_PAGE_DIRTY,\tmp
or \tmp,\pte,\pte
STREG \pte,0(\ptep)
@@ -1187,11 +1223,13 @@ dtlb_miss_20w:

L3_ptep ptp,pte,t0,va,dtlb_check_alias_20w

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

idtlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1211,11 +1249,13 @@ nadtlb_miss_20w:

L3_ptep ptp,pte,t0,va,nadtlb_check_alias_20w

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

idtlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1237,7 +1277,8 @@ dtlb_miss_11:

L2_ptep ptp,pte,t0,va,dtlb_check_alias_11

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb_11 spc,pte,prot

@@ -1248,6 +1289,7 @@ dtlb_miss_11:
idtlbp prot,(%sr1,va)

mtsp t0, %sr1 /* Restore sr1 */
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1268,7 +1310,8 @@ nadtlb_miss_11:

L2_ptep ptp,pte,t0,va,nadtlb_check_alias_11

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb_11 spc,pte,prot

@@ -1280,6 +1323,7 @@ nadtlb_miss_11:
idtlbp prot,(%sr1,va)

mtsp t0, %sr1 /* Restore sr1 */
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1300,13 +1344,15 @@ dtlb_miss_20:

L2_ptep ptp,pte,t0,va,dtlb_check_alias_20

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

f_extend pte,t0

idtlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1326,13 +1372,15 @@ nadtlb_miss_20:

L2_ptep ptp,pte,t0,va,nadtlb_check_alias_20

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

f_extend pte,t0

idtlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1433,11 +1481,13 @@ itlb_miss_20w:

L3_ptep ptp,pte,t0,va,itlb_fault

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

iitlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1455,11 +1505,13 @@ naitlb_miss_20w:

L3_ptep ptp,pte,t0,va,naitlb_check_alias_20w

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

iitlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1481,7 +1533,8 @@ itlb_miss_11:

L2_ptep ptp,pte,t0,va,itlb_fault

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb_11 spc,pte,prot

@@ -1492,6 +1545,7 @@ itlb_miss_11:
iitlbp prot,(%sr1,va)

mtsp t0, %sr1 /* Restore sr1 */
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1503,7 +1557,8 @@ naitlb_miss_11:

L2_ptep ptp,pte,t0,va,naitlb_check_alias_11

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb_11 spc,pte,prot

@@ -1514,6 +1569,7 @@ naitlb_miss_11:
iitlbp prot,(%sr1,va)

mtsp t0, %sr1 /* Restore sr1 */
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1535,13 +1591,15 @@ itlb_miss_20:

L2_ptep ptp,pte,t0,va,itlb_fault

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

f_extend pte,t0

iitlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1553,13 +1611,15 @@ naitlb_miss_20:

L2_ptep ptp,pte,t0,va,naitlb_check_alias_20

- update_ptep ptp,pte,t0,t1
+ dbit_lock spc,t0,t1
+ update_ptep spc,ptp,pte,t0,t1

make_insert_tlb spc,pte,prot

f_extend pte,t0

iitlbt pte,prot
+ dbit_unlock1 spc,t0

rfir
nop
@@ -1583,29 +1643,13 @@ dbit_trap_20w:

L3_ptep ptp,pte,t0,va,dbit_fault

-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nolock_20w
- load32 PA(pa_dbit_lock),t0
-
-dbit_spin_20w:
- LDCW 0(t0),t1
- cmpib,COND(=) 0,t1,dbit_spin_20w
- nop
-
-dbit_nolock_20w:
-#endif
- update_dirty ptp,pte,t1
+ dbit_lock spc,t0,t1
+ update_dirty spc,ptp,pte,t1

make_insert_tlb spc,pte,prot

idtlbt pte,prot
-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nounlock_20w
- ldi 1,t1
- stw t1,0(t0)
-
-dbit_nounlock_20w:
-#endif
+ dbit_unlock0 spc,t0

rfir
nop
@@ -1619,18 +1663,8 @@ dbit_trap_11:

L2_ptep ptp,pte,t0,va,dbit_fault

-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nolock_11
- load32 PA(pa_dbit_lock),t0
-
-dbit_spin_11:
- LDCW 0(t0),t1
- cmpib,= 0,t1,dbit_spin_11
- nop
-
-dbit_nolock_11:
-#endif
- update_dirty ptp,pte,t1
+ dbit_lock spc,t0,t1
+ update_dirty spc,ptp,pte,t1

make_insert_tlb_11 spc,pte,prot

@@ -1641,13 +1675,7 @@ dbit_nolock_11:
idtlbp prot,(%sr1,va)

mtsp t1, %sr1 /* Restore sr1 */
-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nounlock_11
- ldi 1,t1
- stw t1,0(t0)
-
-dbit_nounlock_11:
-#endif
+ dbit_unlock0 spc,t0

rfir
nop
@@ -1659,32 +1687,15 @@ dbit_trap_20:

L2_ptep ptp,pte,t0,va,dbit_fault

-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nolock_20
- load32 PA(pa_dbit_lock),t0
-
-dbit_spin_20:
- LDCW 0(t0),t1
- cmpib,= 0,t1,dbit_spin_20
- nop
-
-dbit_nolock_20:
-#endif
- update_dirty ptp,pte,t1
+ dbit_lock spc,t0,t1
+ update_dirty spc,ptp,pte,t1

make_insert_tlb spc,pte,prot

f_extend pte,t1

idtlbt pte,prot
-
-#ifdef CONFIG_SMP
- cmpib,COND(=),n 0,spc,dbit_nounlock_20
- ldi 1,t1
- stw t1,0(t0)
-
-dbit_nounlock_20:
-#endif
+ dbit_unlock0 spc,t0

rfir
nop
--
1.7.10.4


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