Commit f4125cfd authored by John David Anglin's avatar John David Anglin Committed by Helge Deller
Browse files

parisc: Avoid trashing sr2 and sr3 in LWS code 



There is no need to trash sr2 and sr3 in the Light-weight syscall (LWS).  sr2
already points to kernel space (it's zero in userspace, otherwise syscalls
wouldn't work), and since the LWS code is executed in userspace, we can simply
ignore to preload sr3.

Signed-off-by: default avatarJohn David Anglin <dave.anglin@bell.net>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 6f63d0f6

arch/parisc/kernel/syscall.S

+24 −29
Original line number Diff line number Diff line
@@ -474,11 +474,6 @@ lws_start: 
	comiclr,>>	__NR_lws_entries, %r20, %r0

	b,n	lws_exit_nosys



	/* WARNING: Trashing sr2 and sr3 */

	mfsp	%sr7,%r1			/* get userspace into sr3 */

	mtsp	%r1,%sr3

	mtsp	%r0,%sr2			/* get kernel space into sr2 */



	/* Load table start */

	ldil	L%lws_table, %r1

	ldo	R%lws_table(%r1), %r28	/* Scratch use of r28 */
@@ -627,9 +622,9 @@ cas_action: 
	stw	%r1, 4(%sr2,%r20)

#endif

	/* The load and store could fail */

1:	ldw,ma	0(%sr3,%r26), %r28

1:	ldw,ma	0(%r26), %r28

	sub,<>	%r28, %r25, %r0

2:	stw,ma	%r24, 0(%sr3,%r26)

2:	stw,ma	%r24, 0(%r26)

	/* Free lock */

	stw,ma	%r20, 0(%sr2,%r20)

#if ENABLE_LWS_DEBUG
@@ -706,9 +701,9 @@ lws_compare_and_swap_2: 
	nop



	/* 8bit load */

4:	ldb	0(%sr3,%r25), %r25

4:	ldb	0(%r25), %r25

	b	cas2_lock_start

5:	ldb	0(%sr3,%r24), %r24

5:	ldb	0(%r24), %r24

	nop

	nop

	nop
@@ -716,9 +711,9 @@ lws_compare_and_swap_2: 
	nop



	/* 16bit load */

6:	ldh	0(%sr3,%r25), %r25

6:	ldh	0(%r25), %r25

	b	cas2_lock_start

7:	ldh	0(%sr3,%r24), %r24

7:	ldh	0(%r24), %r24

	nop

	nop

	nop
@@ -726,9 +721,9 @@ lws_compare_and_swap_2: 
	nop



	/* 32bit load */

8:	ldw	0(%sr3,%r25), %r25

8:	ldw	0(%r25), %r25

	b	cas2_lock_start

9:	ldw	0(%sr3,%r24), %r24

9:	ldw	0(%r24), %r24

	nop

	nop

	nop
@@ -737,14 +732,14 @@ lws_compare_and_swap_2: 


	/* 64bit load */

#ifdef CONFIG_64BIT

10:	ldd	0(%sr3,%r25), %r25

11:	ldd	0(%sr3,%r24), %r24

10:	ldd	0(%r25), %r25

11:	ldd	0(%r24), %r24

#else

	/* Load new value into r22/r23 - high/low */

10:	ldw	0(%sr3,%r25), %r22

11:	ldw	4(%sr3,%r25), %r23

10:	ldw	0(%r25), %r22

11:	ldw	4(%r25), %r23

	/* Load new value into fr4 for atomic store later */

12:	flddx	0(%sr3,%r24), %fr4

12:	flddx	0(%r24), %fr4

#endif



cas2_lock_start:
@@ -794,30 +789,30 @@ cas2_action: 
	ldo	1(%r0),%r28



	/* 8bit CAS */

13:	ldb,ma	0(%sr3,%r26), %r29

13:	ldb,ma	0(%r26), %r29

	sub,=	%r29, %r25, %r0

	b,n	cas2_end

14:	stb,ma	%r24, 0(%sr3,%r26)

14:	stb,ma	%r24, 0(%r26)

	b	cas2_end

	copy	%r0, %r28

	nop

	nop



	/* 16bit CAS */

15:	ldh,ma	0(%sr3,%r26), %r29

15:	ldh,ma	0(%r26), %r29

	sub,=	%r29, %r25, %r0

	b,n	cas2_end

16:	sth,ma	%r24, 0(%sr3,%r26)

16:	sth,ma	%r24, 0(%r26)

	b	cas2_end

	copy	%r0, %r28

	nop

	nop



	/* 32bit CAS */

17:	ldw,ma	0(%sr3,%r26), %r29

17:	ldw,ma	0(%r26), %r29

	sub,=	%r29, %r25, %r0

	b,n	cas2_end

18:	stw,ma	%r24, 0(%sr3,%r26)

18:	stw,ma	%r24, 0(%r26)

	b	cas2_end

	copy	%r0, %r28

	nop
@@ -825,22 +820,22 @@ cas2_action: 


	/* 64bit CAS */

#ifdef CONFIG_64BIT

19:	ldd,ma	0(%sr3,%r26), %r29

19:	ldd,ma	0(%r26), %r29

	sub,*=	%r29, %r25, %r0

	b,n	cas2_end

20:	std,ma	%r24, 0(%sr3,%r26)

20:	std,ma	%r24, 0(%r26)

	copy	%r0, %r28

#else

	/* Compare first word */

19:	ldw,ma	0(%sr3,%r26), %r29

19:	ldw,ma	0(%r26), %r29

	sub,=	%r29, %r22, %r0

	b,n	cas2_end

	/* Compare second word */

20:	ldw,ma	4(%sr3,%r26), %r29

20:	ldw,ma	4(%r26), %r29

	sub,=	%r29, %r23, %r0

	b,n	cas2_end

	/* Perform the store */

21:	fstdx	%fr4, 0(%sr3,%r26)

21:	fstdx	%fr4, 0(%r26)

	copy	%r0, %r28

#endif

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