Commit 654abc69 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/vdso32: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 



This is copied and adapted from commit 5c929885 ("powerpc/vdso64:
Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE")
from Santosh Sivaraj <santosh@fossix.org>

Benchmark from vdsotest-all:
clock-gettime-realtime: syscall: 3601 nsec/call
clock-gettime-realtime:    libc: 1072 nsec/call
clock-gettime-realtime:    vdso: 931 nsec/call
clock-gettime-monotonic: syscall: 4034 nsec/call
clock-gettime-monotonic:    libc: 1213 nsec/call
clock-gettime-monotonic:    vdso: 1076 nsec/call
clock-gettime-realtime-coarse: syscall: 2722 nsec/call
clock-gettime-realtime-coarse:    libc: 805 nsec/call
clock-gettime-realtime-coarse:    vdso: 668 nsec/call
clock-gettime-monotonic-coarse: syscall: 2949 nsec/call
clock-gettime-monotonic-coarse:    libc: 882 nsec/call
clock-gettime-monotonic-coarse:    vdso: 745 nsec/call

Additional test passed with:
	vdsotest -d 30 clock-gettime-monotonic-coarse verify

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/linuxppc/issues/issues/41
Link: https://lore.kernel.org/r/d1d24a376e396540194eeb85a2efe481e92ade24.1575273217.git.christophe.leroy@c-s.fr
parent 902137ba

arch/powerpc/kernel/vdso32/gettimeofday.S

+57 −7
Original line number Diff line number Diff line
@@ -69,7 +69,13 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 
	cmpli	cr0,r3,CLOCK_REALTIME

	cmpli	cr1,r3,CLOCK_MONOTONIC

	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq

	bne	cr0,99f



	cmpli	cr5,r3,CLOCK_REALTIME_COARSE

	cmpli	cr6,r3,CLOCK_MONOTONIC_COARSE

	cror	cr5*4+eq,cr5*4+eq,cr6*4+eq



	cror	cr0*4+eq,cr0*4+eq,cr5*4+eq

	bne	cr0, .Lgettime_fallback



	mflr	r12			/* r12 saves lr */

  .cfi_register lr,r12
@@ -78,8 +84,10 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 
	mr	r9,r3			/* datapage ptr in r9 */

	lis	r7,NSEC_PER_SEC@h	/* want nanoseconds */

	ori	r7,r7,NSEC_PER_SEC@l

50:	bl	__do_get_tspec@local	/* get sec/nsec from tb & kernel */

	bne	cr1,80f			/* not monotonic -> all done */

	beq	cr5, .Lcoarse_clocks

.Lprecise_clocks:

	bl	__do_get_tspec@local	/* get sec/nsec from tb & kernel */

	bne	cr1, .Lfinish		/* not monotonic -> all done */



	/*

	 * CLOCK_MONOTONIC
@@ -103,12 +111,53 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 
	add	r9,r9,r0

	lwz	r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)

        cmpl    cr0,r8,r0		/* check if updated */

	bne-	50b

	bne-	.Lprecise_clocks

	b	.Lfinish_monotonic



	/*

	 * For coarse clocks we get data directly from the vdso data page, so

	 * we don't need to call __do_get_tspec, but we still need to do the

	 * counter trick.

	 */

.Lcoarse_clocks:

	lwz	r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)

	andi.	r0,r8,1                 /* pending update ? loop */

	bne-	.Lcoarse_clocks

	add	r9,r9,r0		/* r0 is already 0 */



	/*

	 * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE

	 * too

	 */

	lwz	r3,STAMP_XTIME_SEC+LOPART(r9)

	lwz	r4,STAMP_XTIME_NSEC+LOPART(r9)

	bne	cr6,1f



	/* CLOCK_MONOTONIC_COARSE */

	lwz	r5,(WTOM_CLOCK_SEC+LOPART)(r9)

	lwz	r6,WTOM_CLOCK_NSEC(r9)



	/* check if counter has updated */

	or	r0,r6,r5

1:	or	r0,r0,r3

	or	r0,r0,r4

	xor	r0,r0,r0

	add	r3,r3,r0

	lwz	r0,CFG_TB_UPDATE_COUNT+LOPART(r9)

	cmpl	cr0,r0,r8               /* check if updated */

	bne-	.Lcoarse_clocks



	/* Counter has not updated, so continue calculating proper values for

	 * sec and nsec if monotonic coarse, or just return with the proper

	 * values for realtime.

	 */

	bne	cr6, .Lfinish



	/* Calculate and store result. Note that this mimics the C code,

	 * which may cause funny results if nsec goes negative... is that

	 * possible at all ?

	 */

.Lfinish_monotonic:

	add	r3,r3,r5

	add	r4,r4,r6

	cmpw	cr0,r4,r7
@@ -116,11 +165,12 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 
	blt	1f

	subf	r4,r7,r4

	addi	r3,r3,1

1:	bge	cr1,80f

1:	bge	cr1, .Lfinish

	addi	r3,r3,-1

	add	r4,r4,r7



80:	stw	r3,TSPC32_TV_SEC(r11)

.Lfinish:

	stw	r3,TSPC32_TV_SEC(r11)

	stw	r4,TSPC32_TV_NSEC(r11)



	mtlr	r12
@@ -131,7 +181,7 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) 
	/*

	 * syscall fallback

	 */

99:

.Lgettime_fallback:

	li	r0,__NR_clock_gettime

  .cfi_restore lr

	sc

CRA Git | Maintained and supported by SUSTech CRA and CCSE