Commit f0a18819 authored by John David Anglin's avatar John David Anglin Committed by Helge Deller
Browse files

parisc: fix SMP races when updating PTE and TLB entries in entry.S 



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: default avatarJohn David Anglin <dave.anglin@bell.net>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 416821d3

arch/parisc/kernel/entry.S

+83 −72
Original line number Diff line number Diff line
@@ -452,9 +452,41 @@ 
	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
@@ -463,7 +495,11 @@ 


	/* 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)
@@ -1111,11 +1147,13 @@ 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
@@ -1135,11 +1173,13 @@ 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
@@ -1161,7 +1201,8 @@ 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
@@ -1172,6 +1213,7 @@ dtlb_miss_11: 
	idtlbp		prot,(%sr1,va)



	mtsp		t0, %sr1	/* Restore sr1 */

	dbit_unlock1	spc,t0



	rfir

	nop
@@ -1192,7 +1234,8 @@ 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
@@ -1204,6 +1247,7 @@ nadtlb_miss_11: 
	idtlbp		prot,(%sr1,va)



	mtsp		t0, %sr1	/* Restore sr1 */

	dbit_unlock1	spc,t0



	rfir

	nop
@@ -1224,13 +1268,15 @@ 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
@@ -1250,13 +1296,15 @@ 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
@@ -1357,11 +1405,13 @@ 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
@@ -1379,11 +1429,13 @@ 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
@@ -1405,7 +1457,8 @@ 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
@@ -1416,6 +1469,7 @@ itlb_miss_11: 
	iitlbp		prot,(%sr1,va)



	mtsp		t0, %sr1	/* Restore sr1 */

	dbit_unlock1	spc,t0



	rfir

	nop
@@ -1427,7 +1481,8 @@ 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
@@ -1438,6 +1493,7 @@ naitlb_miss_11: 
	iitlbp		prot,(%sr1,va)



	mtsp		t0, %sr1	/* Restore sr1 */

	dbit_unlock1	spc,t0



	rfir

	nop
@@ -1459,13 +1515,15 @@ 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
@@ -1477,13 +1535,15 @@ 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
@@ -1507,29 +1567,13 @@ 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
@@ -1543,18 +1587,8 @@ 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
@@ -1565,13 +1599,7 @@ 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
@@ -1583,32 +1611,15 @@ 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

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