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

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This is copied and adapted from commit 5c929885f1 ("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: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael 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
This commit is contained in:
Christophe Leroy 2019-12-02 07:57:28 +00:00 • committed by Michael Ellerman
parent 902137ba8e
commit 654abc69ef
1 changed files with 57 additions and 7 deletions
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64
arch/powerpc/kernel/vdso32/gettimeofday.S
View file

@ -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