This is copied and adapted from commit 5c929885f1bb ("powerpc/vdso64:
Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE")
from Santosh Sivaraj <sant...@fossix.org>Benchmark from vdsotest: 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 Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> Cc: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> Cc: Santosh Sivaraj <sant...@fossix.org> Link: https://github.com/linuxppc/issues/issues/41 --- arch/powerpc/kernel/vdso32/gettimeofday.S | 48 ++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index becd9f8767ed..e10098cde89c 100644 --- a/arch/powerpc/kernel/vdso32/gettimeofday.S +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S @@ -71,6 +71,12 @@ 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 + + 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 cr0,99f mflr r12 /* r12 saves lr */ @@ -80,6 +86,7 @@ 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 + beq cr5,70f 50: bl __do_get_tspec@local /* get sec/nsec from tb & kernel */ bne cr1,80f /* not monotonic -> all done */ @@ -106,12 +113,51 @@ V_FUNCTION_BEGIN(__kernel_clock_gettime) lwz r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9) cmpl cr0,r8,r0 /* check if updated */ bne- 50b + b 78f + + /* + * 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. + */ +70: lwz r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9) + andi. r0,r8,1 /* pending update ? loop */ + bne- 70b + add r9,r9,r0 /* r0 is already 0 */ + + /* + * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE + * too + */ + lwz r3,STAMP_XTIME+TSPC32_TV_SEC(r9) + lwz r4,STAMP_XTIME+TSPC32_TV_NSEC(r9) + bne cr6,75f + + /* 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 +75: 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- 70b + + /* 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 cr6,80f /* 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 ? */ - add r3,r3,r5 +78: add r3,r3,r5 add r4,r4,r6 cmpw cr0,r4,r7 cmpwi cr1,r4,0 -- 2.13.3
