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Diffstat (limited to 'arch/s390/kernel/vdso64/clock_gettime.S')
-rw-r--r--arch/s390/kernel/vdso64/clock_gettime.S89
1 files changed, 89 insertions, 0 deletions
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S
new file mode 100644
index 000000000000..738a410b7eb2
--- /dev/null
+++ b/arch/s390/kernel/vdso64/clock_gettime.S
@@ -0,0 +1,89 @@
+/*
+ * Userland implementation of clock_gettime() for 64 bits processes in a
+ * s390 kernel for use in the vDSO
+ *
+ * Copyright IBM Corp. 2008
+ * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+#include <asm/vdso.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+ .text
+ .align 4
+ .globl __kernel_clock_gettime
+ .type __kernel_clock_gettime,@function
+__kernel_clock_gettime:
+ .cfi_startproc
+ larl %r5,_vdso_data
+ cghi %r2,CLOCK_REALTIME
+ je 4f
+ cghi %r2,CLOCK_MONOTONIC
+ jne 9f
+
+ /* CLOCK_MONOTONIC */
+ ltgr %r3,%r3
+ jz 3f /* tp == NULL */
+0: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
+ tmll %r4,0x0001 /* pending update ? loop */
+ jnz 0b
+ stck 48(%r15) /* Store TOD clock */
+ lg %r1,48(%r15)
+ sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
+ mghi %r1,1000
+ srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
+ alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
+ lg %r0,__VDSO_XTIME_SEC(%r5)
+ alg %r1,__VDSO_WTOM_NSEC(%r5) /* + wall_to_monotonic */
+ alg %r0,__VDSO_WTOM_SEC(%r5)
+ clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
+ jne 0b
+ larl %r5,10f
+1: clg %r1,0(%r5)
+ jl 2f
+ slg %r1,0(%r5)
+ aghi %r0,1
+ j 1b
+2: stg %r0,0(%r3) /* store tp->tv_sec */
+ stg %r1,8(%r3) /* store tp->tv_nsec */
+3: lghi %r2,0
+ br %r14
+
+ /* CLOCK_REALTIME */
+4: ltr %r3,%r3 /* tp == NULL */
+ jz 8f
+5: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
+ tmll %r4,0x0001 /* pending update ? loop */
+ jnz 5b
+ stck 48(%r15) /* Store TOD clock */
+ lg %r1,48(%r15)
+ sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
+ mghi %r1,1000
+ srlg %r1,%r1,12 /* cyc2ns(clock,cycle_delta) */
+ alg %r1,__VDSO_XTIME_NSEC(%r5) /* + xtime */
+ lg %r0,__VDSO_XTIME_SEC(%r5)
+ clg %r4,__VDSO_UPD_COUNT(%r5) /* check update counter */
+ jne 5b
+ larl %r5,10f
+6: clg %r1,0(%r5)
+ jl 7f
+ slg %r1,0(%r5)
+ aghi %r0,1
+ j 6b
+7: stg %r0,0(%r3) /* store tp->tv_sec */
+ stg %r1,8(%r3) /* store tp->tv_nsec */
+8: lghi %r2,0
+ br %r14
+
+ /* Fallback to system call */
+9: lghi %r1,__NR_clock_gettime
+ svc 0
+ br %r14
+
+10: .quad 1000000000
+ .cfi_endproc
+ .size __kernel_clock_gettime,.-__kernel_clock_gettime