[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel

This patch moves the vdso's to arch/powerpc, adds support for the 32
bits vdso to the 32 bits kernel, rename systemcfg (finally !), and adds
some new (still untested) routines to both vdso's: clock_gettime() with
support for CLOCK_REALTIME and CLOCK_MONOTONIC, clock_getres() (same
clocks) and get_tbfreq() for glibc to retreive the timebase frequency.

Tom,Steve: The implementation of get_tbfreq() I've done for 32 bits
returns a long long (r3, r4) not a long. This is such that if we ever
add support for >4Ghz timebases on ppc32, the userland interface won't
have to change.

I have tested gettimeofday() using some glibc patches in both ppc32 and
ppc64 kernels using 32 bits userland (I haven't had a chance to test a
64 bits userland yet, but the implementation didn't change and was
tested earlier). I haven't tested yet the new functions.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/vdso64/datapage.S

@@ -0,0 +1,84 @@
+/*
+ * Access to the shared data page by the vDSO & syscall map
+ *
+ * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+#include <asm/vdso.h>
+
+	.text
+V_FUNCTION_BEGIN(__get_datapage)
+  .cfi_startproc
+	/* We don't want that exposed or overridable as we want other objects
+	 * to be able to bl directly to here
+	 */
+	.protected __get_datapage
+	.hidden __get_datapage
+
+	mflr	r0
+  .cfi_register lr,r0
+
+	bcl	20,31,1f
+	.global	__kernel_datapage_offset;
+__kernel_datapage_offset:
+	.long	0
+1:
+	mflr	r3
+	mtlr	r0
+	lwz	r0,0(r3)
+	add	r3,r0,r3
+	blr
+  .cfi_endproc
+V_FUNCTION_END(__get_datapage)
+
+/*
+ * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
+ *
+ * returns a pointer to the syscall map. the map is agnostic to the
+ * size of "long", unlike kernel bitops, it stores bits from top to
+ * bottom so that memory actually contains a linear bitmap
+ * check for syscall N by testing bit (0x80000000 >> (N & 0x1f)) of
+ * 32 bits int at N >> 5.
+ */
+V_FUNCTION_BEGIN(__kernel_get_syscall_map)
+  .cfi_startproc
+	mflr	r12
+  .cfi_register lr,r12
+
+	mr	r4,r3
+	bl	V_LOCAL_FUNC(__get_datapage)
+	mtlr	r12
+	addi	r3,r3,CFG_SYSCALL_MAP64
+	cmpli	cr0,r4,0
+	beqlr
+	li	r0,__NR_syscalls
+	stw	r0,0(r4)
+	blr
+  .cfi_endproc
+V_FUNCTION_END(__kernel_get_syscall_map)
+
+
+/*
+ * void unsigned long  __kernel_get_tbfreq(void);
+ *
+ * returns the timebase frequency in HZ
+ */
+V_FUNCTION_BEGIN(__kernel_get_tbfreq)
+  .cfi_startproc
+	mflr	r12
+  .cfi_register lr,r12
+	bl	V_LOCAL_FUNC(__get_datapage)
+	ld	r3,CFG_TB_TICKS_PER_SEC(r3)
+	mtlr	r12
+  .cfi_endproc
+V_FUNCTION_END(__kernel_get_tbfreq)