[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>

1 files changed, 315 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
new file mode 100644
index 000000000000..aeb5fc9b87b3
--- /dev/null
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -0,0 +1,315 @@
+/*
+ * Userland implementation of gettimeofday() for 32 bits processes in a
+ * ppc64 kernel for use in the vDSO
+ *
+ * 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/vdso.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+	.text
+/*
+ * Exact prototype of gettimeofday
+ *
+ * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_gettimeofday)
+  .cfi_startproc
+	mflr	r12
+  .cfi_register lr,r12
+
+	mr	r10,r3			/* r10 saves tv */
+	mr	r11,r4			/* r11 saves tz */
+	bl	__get_datapage@local	/* get data page */
+	mr	r9, r3			/* datapage ptr in r9 */
+	bl	__do_get_xsec@local	/* get xsec from tb & kernel */
+	bne-	2f			/* out of line -> do syscall */
+
+	/* seconds are xsec >> 20 */
+	rlwinm	r5,r4,12,20,31
+	rlwimi	r5,r3,12,0,19
+	stw	r5,TVAL32_TV_SEC(r10)
+
+	/* get remaining xsec and convert to usec. we scale
+	 * up remaining xsec by 12 bits and get the top 32 bits
+	 * of the multiplication
+	 */
+	rlwinm	r5,r4,12,0,19
+	lis	r6,1000000@h
+	ori	r6,r6,1000000@l
+	mulhwu	r5,r5,r6
+	stw	r5,TVAL32_TV_USEC(r10)
+
+	cmpli	cr0,r11,0		/* check if tz is NULL */
+	beq	1f
+	lwz	r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
+	lwz	r5,CFG_TZ_DSTTIME(r9)
+	stw	r4,TZONE_TZ_MINWEST(r11)
+	stw	r5,TZONE_TZ_DSTTIME(r11)
+
+1:	mtlr	r12
+	li	r3,0
+	blr
+
+2:
+	mtlr	r12
+	mr	r3,r10
+	mr	r4,r11
+	li	r0,__NR_gettimeofday
+	sc
+	blr
+  .cfi_endproc
+V_FUNCTION_END(__kernel_gettimeofday)
+
+/*
+ * Exact prototype of clock_gettime()
+ *
+ * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_clock_gettime)
+  .cfi_startproc
+	/* Check for supported clock IDs */
+	cmpli	cr0,r3,CLOCK_REALTIME
+	cmpli	cr1,r3,CLOCK_MONOTONIC
+	cror	cr0,cr0,cr1
+	bne	cr0,99f
+
+	mflr	r12			/* r12 saves lr */
+  .cfi_register lr,r12
+	mr	r10,r3			/* r10 saves id */
+	mr	r11,r4			/* r11 saves tp */
+	bl	__get_datapage@local	/* get data page */
+	mr	r9, r3			/* datapage ptr in r9 */
+	beq	cr1,50f			/* if monotonic -> jump there */
+
+	/*
+	 * CLOCK_REALTIME
+	 */
+
+	bl	__do_get_xsec@local	/* get xsec from tb & kernel */
+	bne-	98f			/* out of line -> do syscall */
+
+	/* seconds are xsec >> 20 */
+	rlwinm	r5,r4,12,20,31
+	rlwimi	r5,r3,12,0,19
+	stw	r5,TSPC32_TV_SEC(r11)
+
+	/* get remaining xsec and convert to nsec. we scale
+	 * up remaining xsec by 12 bits and get the top 32 bits
+	 * of the multiplication, then we multiply by 1000
+	 */
+	rlwinm	r5,r4,12,0,19
+	lis	r6,1000000@h
+	ori	r6,r6,1000000@l
+	mulhwu	r5,r5,r6
+	mulli	r5,r5,1000
+	stw	r5,TSPC32_TV_NSEC(r11)
+	mtlr	r12
+	li	r3,0
+	blr
+
+	/*
+	 * CLOCK_MONOTONIC
+	 */
+
+50:	bl	__do_get_xsec@local	/* get xsec from tb & kernel */
+	bne-	98f			/* out of line -> do syscall */
+
+	/* seconds are xsec >> 20 */
+	rlwinm	r6,r4,12,20,31
+	rlwimi	r6,r3,12,0,19
+
+	/* get remaining xsec and convert to nsec. we scale
+	 * up remaining xsec by 12 bits and get the top 32 bits
+	 * of the multiplication, then we multiply by 1000
+	 */
+	rlwinm	r7,r4,12,0,19
+	lis	r5,1000000@h
+	ori	r5,r5,1000000@l
+	mulhwu	r7,r7,r5
+	mulli	r7,r7,1000
+
+	/* now we must fixup using wall to monotonic. We need to snapshot
+	 * that value and do the counter trick again. Fortunately, we still
+	 * have the counter value in r8 that was returned by __do_get_xsec.
+	 * At this point, r6,r7 contain our sec/nsec values, r3,r4 and r5
+	 * can be used
+	 */
+
+	lwz	r3,WTOM_CLOCK_SEC(r9)
+	lwz	r4,WTOM_CLOCK_NSEC(r9)
+
+	/* We now have our result in r3,r4. We create a fake dependency
+	 * on that result and re-check the counter
+	 */
+	or	r5,r4,r3
+	xor	r0,r5,r5
+	add	r9,r9,r0
+#ifdef CONFIG_PPC64
+	lwz	r0,(CFG_TB_UPDATE_COUNT+4)(r9)
+#else
+	lwz	r0,(CFG_TB_UPDATE_COUNT)(r9)
+#endif
+        cmpl    cr0,r8,r0		/* check if updated */
+	bne-	50b
+
+	/* Calculate and store result. Note that this mimmics the C code,
+	 * which may cause funny results if nsec goes negative... is that
+	 * possible at all ?
+	 */
+	add	r3,r3,r6
+	add	r4,r4,r7
+	lis	r5,NSEC_PER_SEC@h
+	ori	r5,r5,NSEC_PER_SEC@l
+	cmpli	cr0,r4,r5
+	blt	1f
+	subf	r4,r5,r4
+	addi	r3,r3,1
+1:	stw	r3,TSPC32_TV_SEC(r11)
+	stw	r4,TSPC32_TV_NSEC(r11)
+
+	mtlr	r12
+	li	r3,0
+	blr
+
+	/*
+	 * syscall fallback
+	 */
+98:
+	mtlr	r12
+	mr	r3,r10
+	mr	r4,r11
+99:
+	li	r0,__NR_clock_gettime
+	sc
+	blr
+  .cfi_endproc
+V_FUNCTION_END(__kernel_clock_gettime)
+
+
+/*
+ * Exact prototype of clock_getres()
+ *
+ * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
+ *
+ */
+V_FUNCTION_BEGIN(__kernel_clock_getres)
+  .cfi_startproc
+	/* Check for supported clock IDs */
+	cmpwi	cr0,r3,CLOCK_REALTIME
+	cmpwi	cr1,r3,CLOCK_MONOTONIC
+	cror	cr0,cr0,cr1
+	bne	cr0,99f
+
+	li	r3,0
+	cmpli	cr0,r4,0
+	beqlr
+	lis	r5,CLOCK_REALTIME_RES@h
+	ori	r5,r5,CLOCK_REALTIME_RES@l
+	stw	r3,TSPC32_TV_SEC(r4)
+	stw	r5,TSPC32_TV_NSEC(r4)
+	blr
+
+	/*
+	 * syscall fallback
+	 */
+99:
+	li	r0,__NR_clock_getres
+	sc
+	blr
+  .cfi_endproc
+V_FUNCTION_END(__kernel_clock_getres)
+
+
+/*
+ * This is the core of gettimeofday() & friends, it returns the xsec
+ * value in r3 & r4 and expects the datapage ptr (non clobbered)
+ * in r9. clobbers r0,r4,r5,r6,r7,r8.
+ * When returning, r8 contains the counter value that can be reused
+ * by the monotonic clock implementation
+ */
+__do_get_xsec:
+  .cfi_startproc
+	/* Check for update count & load values. We use the low
+	 * order 32 bits of the update count
+	 */
+#ifdef CONFIG_PPC64
+1:	lwz	r8,(CFG_TB_UPDATE_COUNT+4)(r9)
+#else
+1:	lwz	r8,(CFG_TB_UPDATE_COUNT)(r9)
+#endif
+	andi.	r0,r8,1			/* pending update ? loop */
+	bne-	1b
+	xor	r0,r8,r8		/* create dependency */
+	add	r9,r9,r0
+
+	/* Load orig stamp (offset to TB) */
+	lwz	r5,CFG_TB_ORIG_STAMP(r9)
+	lwz	r6,(CFG_TB_ORIG_STAMP+4)(r9)
+
+	/* Get a stable TB value */
+2:	mftbu	r3
+	mftbl	r4
+	mftbu	r0
+	cmpl	cr0,r3,r0
+	bne-	2b
+
+	/* Substract tb orig stamp. If the high part is non-zero, we jump to
+	 * the slow path which call the syscall.
+	 * If it's ok, then we have our 32 bits tb_ticks value in r7
+	 */
+	subfc	r7,r6,r4
+	subfe.	r0,r5,r3
+	bne-	3f
+
+	/* Load scale factor & do multiplication */
+	lwz	r5,CFG_TB_TO_XS(r9)	/* load values */
+	lwz	r6,(CFG_TB_TO_XS+4)(r9)
+	mulhwu	r4,r7,r5
+	mulhwu	r6,r7,r6
+	mullw	r0,r7,r5
+	addc	r6,r6,r0
+
+	/* At this point, we have the scaled xsec value in r4 + XER:CA
+	 * we load & add the stamp since epoch
+	 */
+	lwz	r5,CFG_STAMP_XSEC(r9)
+	lwz	r6,(CFG_STAMP_XSEC+4)(r9)
+	adde	r4,r4,r6
+	addze	r3,r5
+
+	/* We now have our result in r3,r4. We create a fake dependency
+	 * on that result and re-check the counter
+	 */
+	or	r6,r4,r3
+	xor	r0,r6,r6
+	add	r9,r9,r0
+#ifdef CONFIG_PPC64
+	lwz	r0,(CFG_TB_UPDATE_COUNT+4)(r9)
+#else
+	lwz	r0,(CFG_TB_UPDATE_COUNT)(r9)
+#endif
+        cmpl    cr0,r8,r0		/* check if updated */
+	bne-	1b
+
+	/* Warning ! The caller expects CR:EQ to be set to indicate a
+	 * successful calculation (so it won't fallback to the syscall
+	 * method). We have overriden that CR bit in the counter check,
+	 * but fortunately, the loop exit condition _is_ CR:EQ set, so
+	 * we can exit safely here. If you change this code, be careful
+	 * of that side effect.
+	 */
+3:	blr
+  .cfi_endproc