s390: convert to GENERIC_VDSO

Convert s390 to generic vDSO. There are a few special things on s390:

- vDSO can be called without a stack frame - glibc did this in the past.
  So we need to allocate a stackframe on our own.

- The former assembly code used stcke to get the TOD clock and applied
  time steering to it. We need to do the same in the new code. This is done
  in the architecture specific __arch_get_hw_counter function. The steering
  information is stored in an architecure specific area in the vDSO data.

- CPUCLOCK_VIRT is now handled with a syscall fallback, which might
  be slower/less accurate than the old implementation.

The getcpu() function stays as an assembly function because there is no
generic implementation and the code is just a few lines.

Performance number from my system do 100 mio gettimeofday() calls:

Plain syscall: 8.6s
Generic VDSO:  1.3s
old ASM VDSO:  1s

So it's a bit slower but still much faster than syscalls.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 0 insertions, 50 deletions

diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S
deleted file mode 100644
index 0c79caa32b59..000000000000
--- a/arch/s390/kernel/vdso64/clock_getres.S
+++ /dev/null
@@ -1,50 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Userland implementation of clock_getres() 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)
- */
-#include <asm/vdso.h>
-#include <asm/asm-offsets.h>
-#include <asm/unistd.h>
-#include <asm/dwarf.h>
-
-	.text
-	.align 4
-	.globl __kernel_clock_getres
-	.type  __kernel_clock_getres,@function
-__kernel_clock_getres:
-	CFI_STARTPROC
-	larl	%r1,3f
-	lg	%r0,0(%r1)
-	cghi	%r2,__CLOCK_REALTIME_COARSE
-	je	0f
-	cghi	%r2,__CLOCK_MONOTONIC_COARSE
-	je	0f
-	larl	%r1,_vdso_data
-	llgf	%r0,__VDSO_CLOCK_REALTIME_RES(%r1)
-	cghi	%r2,__CLOCK_REALTIME
-	je	0f
-	cghi	%r2,__CLOCK_MONOTONIC
-	je	0f
-	cghi	%r2,__CLOCK_THREAD_CPUTIME_ID
-	je	0f
-	cghi	%r2,-2		/* Per-thread CPUCLOCK with PID=0, VIRT=1 */
-	jne	2f
-	larl	%r5,_vdso_data
-	icm	%r0,15,__LC_ECTG_OK(%r5)
-	jz	2f
-0:	ltgr	%r3,%r3
-	jz	1f				/* res == NULL */
-	xc	0(8,%r3),0(%r3)			/* set tp->tv_sec to zero */
-	stg	%r0,8(%r3)			/* store tp->tv_usec */
-1:	lghi	%r2,0
-	br	%r14
-2:	lghi	%r1,__NR_clock_getres		/* fallback to svc */
-	svc	0
-	br	%r14
-	CFI_ENDPROC
-3:	.quad	__CLOCK_COARSE_RES
-	.size	__kernel_clock_getres,.-__kernel_clock_getres