From c742b31c03f37c5c499178f09f57381aa6c70131 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 31 Dec 2008 15:11:42 +0100 Subject: [PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID The extract cpu time instruction (ectg) instruction allows the user process to get the current thread cputime without calling into the kernel. The code that uses the instruction needs to switch to the access registers mode to get access to the per-cpu info page that contains the two base values that are needed to calculate the current cputime from the CPU timer with the ectg instruction. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/vdso64/clock_getres.S | 5 +++++ arch/s390/kernel/vdso64/clock_gettime.S | 39 ++++++++++++++++++++++++++++----- 2 files changed, 39 insertions(+), 5 deletions(-) (limited to 'arch/s390/kernel/vdso64') diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S index 488e31a3c0e7..9ce8caafdb4e 100644 --- a/arch/s390/kernel/vdso64/clock_getres.S +++ b/arch/s390/kernel/vdso64/clock_getres.S @@ -22,7 +22,12 @@ __kernel_clock_getres: cghi %r2,CLOCK_REALTIME je 0f cghi %r2,CLOCK_MONOTONIC + je 0f + cghi %r2,-2 /* CLOCK_THREAD_CPUTIME_ID for this thread */ jne 2f + larl %r5,_vdso_data + icm %r0,15,__LC_ECTG_OK(%r5) + jz 2f 0: ltgr %r3,%r3 jz 1f /* res == NULL */ larl %r1,3f diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S index 738a410b7eb2..79dbfee831ec 100644 --- a/arch/s390/kernel/vdso64/clock_gettime.S +++ b/arch/s390/kernel/vdso64/clock_gettime.S @@ -22,8 +22,10 @@ __kernel_clock_gettime: larl %r5,_vdso_data cghi %r2,CLOCK_REALTIME je 4f + cghi %r2,-2 /* CLOCK_THREAD_CPUTIME_ID for this thread */ + je 9f cghi %r2,CLOCK_MONOTONIC - jne 9f + jne 12f /* CLOCK_MONOTONIC */ ltgr %r3,%r3 @@ -42,7 +44,7 @@ __kernel_clock_gettime: alg %r0,__VDSO_WTOM_SEC(%r5) clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */ jne 0b - larl %r5,10f + larl %r5,13f 1: clg %r1,0(%r5) jl 2f slg %r1,0(%r5) @@ -68,7 +70,7 @@ __kernel_clock_gettime: lg %r0,__VDSO_XTIME_SEC(%r5) clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */ jne 5b - larl %r5,10f + larl %r5,13f 6: clg %r1,0(%r5) jl 7f slg %r1,0(%r5) @@ -79,11 +81,38 @@ __kernel_clock_gettime: 8: lghi %r2,0 br %r14 + /* CLOCK_THREAD_CPUTIME_ID for this thread */ +9: icm %r0,15,__VDSO_ECTG_OK(%r5) + jz 12f + ear %r2,%a4 + llilh %r4,0x0100 + sar %a4,%r4 + lghi %r4,0 + sacf 512 /* Magic ectg instruction */ + .insn ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4 + sacf 0 + sar %a4,%r2 + algr %r1,%r0 /* r1 = cputime as TOD value */ + mghi %r1,1000 /* convert to nanoseconds */ + srlg %r1,%r1,12 /* r1 = cputime in nanosec */ + lgr %r4,%r1 + larl %r5,13f + srlg %r1,%r1,9 /* divide by 1000000000 */ + mlg %r0,8(%r5) + srlg %r0,%r0,11 /* r0 = tv_sec */ + stg %r0,0(%r3) + msg %r0,0(%r5) /* calculate tv_nsec */ + slgr %r4,%r0 /* r4 = tv_nsec */ + stg %r4,8(%r3) + lghi %r2,0 + br %r14 + /* Fallback to system call */ -9: lghi %r1,__NR_clock_gettime +12: lghi %r1,__NR_clock_gettime svc 0 br %r14 -10: .quad 1000000000 +13: .quad 1000000000 +14: .quad 19342813113834067 .cfi_endproc .size __kernel_clock_gettime,.-__kernel_clock_gettime -- cgit v1.2.3