[patch 0/5] powerpc 2.6.21-rt1] latency trace support for powerpc

[patch 0/5] powerpc 2.6.21-rt1] latency trace support for powerpc

[Tsutomu OWA]

Hi Ingo,

  Please consider for inclusion.

  This series of patches adds very basic latency trace support for powerpc.

  Compile, boot and trace tested (a little) on Celleb.

  Thanks in advance.

-- owa
TOSHIBA, Corprate Software Engineering Center.

Re: [patch 1/5] powerpc 2.6.21-rt1: add mcount() and _mcount()

[Tsutomu OWA]

add mcount() and _mcount() for latency trace support.

Signed-off-by: Tsutomu OWA <tsutomu.owa@toshiba.co.jp>
-- owa

diff -rup linux-2.6.21-rt1/arch/powerpc/kernel/entry_64.S rt/arch/powerpc/kernel/entry_64.S
--- linux-2.6.21-rt1/arch/powerpc/kernel/entry_64.S	2007-05-07 14:08:12.000000000 +0900
+++ rt/arch/powerpc/kernel/entry_64.S	2007-05-08 18:54:07.000000000 +0900
@@ -832,3 +832,63 @@ _GLOBAL(enter_prom)
 	ld	r0,16(r1)
 	mtlr    r0
         blr
+
+#ifdef CONFIG_MCOUNT
+/*
+ * code almost taken from entry_32.S
+ */
+#define MCOUNT_FRAME_SIZE 32
+_GLOBAL(mcount)
+	stdu	r1,-MCOUNT_FRAME_SIZE(r1)
+	mflr	r3
+
+	LOAD_REG_ADDR(r5,mcount_enabled)
+	lwz	r5,0(r5)
+	std	r3,MCOUNT_FRAME_SIZE+16(r1)
+	cmpwi	r5,0
+	beq	1f
+
+	/* r3 contains lr (eip), put parent lr (parent_eip) in r4 */
+	ld	r4,MCOUNT_FRAME_SIZE(r1)
+	ld	r4,16(r4)
+	bl	.__trace
+	nop
+1:
+	ld	r0,MCOUNT_FRAME_SIZE+16(r1)
+	mtlr	r0
+	addi	r1,r1,MCOUNT_FRAME_SIZE
+	blr
+
+/*
+ * Based on glibc-2.4/sysdeps/powerpc/powerpc64/ppc-mcount.S
+ *
+ * We don't need to save the parameter-passing registers as gcc takes
+ * care of that for us.  Thus this function looks fairly normal.
+ * In fact, the generic code would work for us.
+ */
+_GLOBAL(_mcount)
+	/* return if we're in real mode. */
+	mfmsr	r3
+	andi.	r0,r3,MSR_IR|MSR_DR		/* see if relocation is on? */
+	beqlr					/* if not, do nothing. */
+	/* we're in translation mode. keep going. */
+	mflr	r3
+	ld	r11,0(r1)			/* load back chain ptr */
+	stdu	r1,-STACK_FRAME_OVERHEAD(r1)
+	std	r3,STACK_FRAME_OVERHEAD+16(r1)
+	ld	r4,16(r11)			/* LR in back chain */
+	LOAD_REG_ADDR(r5,mcount_enabled)
+	lwz	r5,0(r5)
+	cmpwi	r5,0				/* see if mcount_enabled? */
+	beq	1f				/* if disabled, then skip */
+
+	/* r3 contains lr (eip), put parent lr (parent_eip) in r4 */
+	bl	 .__trace
+	nop
+1:
+	ld	r0,STACK_FRAME_OVERHEAD+16(r1)	/* restore saved LR */
+	mtlr	r0
+	addi	r1,r1,STACK_FRAME_OVERHEAD
+	blr
+
+#endif /* CONFIG_MCOUNT */

Re: [patch 2/5] powerpc 2.6.21-rt1: dummy functions and export _mcount to compile

[Tsutomu OWA]

add dummy functions save_stack_trace(), early_printk() for now and
export _mcount to compile.

Signed-off-by: Tsutomu OWA <tsutomu.owa@toshiba.co.jp>
-- owa

diff -rup linux-2.6.21-rt1/arch/powerpc/kernel/setup_64.c rt/arch/powerpc/kernel/setup_64.c
--- linux-2.6.21-rt1/arch/powerpc/kernel/setup_64.c	2007-04-26 12:08:32.000000000 +0900
+++ rt/arch/powerpc/kernel/setup_64.c	2007-05-08 18:50:46.000000000 +0900
@@ -606,3 +606,22 @@ struct ppc_pci_io ppc_pci_io;
 EXPORT_SYMBOL(ppc_pci_io);
 #endif /* CONFIG_PPC_INDIRECT_IO */
 
+#ifdef CONFIG_STACKTRACE
+#include <linux/stacktrace.h>
+void notrace save_stack_trace(struct stack_trace *trace,
+		      struct task_struct *task)
+{
+}
+#endif /* CONFIG_STACKTRACE */
+
+#ifdef CONFIG_EARLY_PRINTK
+void notrace early_printk(const char *fmt, ...)
+{
+	BUG();
+}
+#endif /* CONFIG_EARLY_PRINTK */
+
+#ifdef CONFIG_MCOUNT
+extern void _mcount(void);
+EXPORT_SYMBOL(_mcount);
+#endif /* CONFIG_MCOUNT */

Re: [patch 3/5] powerpc 2.6.21-rt1: mark raw_local_irq_restore() and timebase_read() as notrace

[Tsutomu OWA]

mark raw_local_irq_restore() and timebase_read() as notrace since
these are called from __trace().

Signed-off-by: Tsutomu OWA <tsutomu.owa@toshiba.co.jp>
-- owa

diff -rup linux-2.6.21-rt1/arch/powerpc/kernel/irq.c rt/arch/powerpc/kernel/irq.c
--- linux-2.6.21-rt1/arch/powerpc/kernel/irq.c	2007-05-07 14:08:12.000000000 +0900
+++ rt/arch/powerpc/kernel/irq.c	2007-05-07 14:05:30.000000000 +0900
@@ -111,7 +111,7 @@ static inline void set_soft_enabled(unsi
 	: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
 }
 
-void raw_local_irq_restore(unsigned long en)
+void notrace raw_local_irq_restore(unsigned long en)
 {
 	/*
 	 * get_paca()->soft_enabled = en;
--- linux-2.6.21-rt1/arch/powerpc/kernel/time.c	2007-05-09 17:52:05.000000000 +0900
+++ rt/arch/powerpc/kernel/time.c	2007-05-09 18:03:39.000000000 +0900
@@ -923,7 +923,7 @@ void div128_by_32(u64 dividend_high, u64
 
 #include <linux/clocksource.h>
 
-static cycle_t timebase_read(void)
+static cycle_t notrace timebase_read(void)
 {
 	return (cycle_t)get_tb();
 }

Re: [patch 4/5] powerpc 2.6.21-rt1: rename mcount variable in xmon to xmon_mcount

[Tsutomu OWA]

Rename variable name "mcount" in xmon to xmon_mcount, since it conflicts 
with mcount() function used by latency trace function.

Signed-off-by: Tsutomu OWA <tsutomu.owa@toshiba.co.jp>
-- owa

diff -rup linux-2.6.21-rt1/arch/powerpc/xmon/xmon.c rt/arch/powerpc/xmon/xmon.c
--- linux-2.6.21-rt1/arch/powerpc/xmon/xmon.c	2007-05-07 14:08:12.000000000 +0900
+++ rt/arch/powerpc/xmon/xmon.c	2007-05-07 14:05:30.000000000 +0900
@@ -2129,7 +2129,7 @@ print_address(unsigned long addr)
 static unsigned long mdest;		/* destination address */
 static unsigned long msrc;		/* source address */
 static unsigned long mval;		/* byte value to set memory to */
-static unsigned long mcount;		/* # bytes to affect */
+static unsigned long xmon_mcount;	/* # bytes to affect */
 static unsigned long mdiffs;		/* max # differences to print */
 
 void
@@ -2141,19 +2141,20 @@ memops(int cmd)
 	scanhex((void *)(cmd == 's'? &mval: &msrc));
 	if( termch != '\n' )
 		termch = 0;
-	scanhex((void *)&mcount);
+	scanhex((void *)&xmon_mcount);
 	switch( cmd ){
 	case 'm':
-		memmove((void *)mdest, (void *)msrc, mcount);
+		memmove((void *)mdest, (void *)msrc, xmon_mcount);
 		break;
 	case 's':
-		memset((void *)mdest, mval, mcount);
+		memset((void *)mdest, mval, xmon_mcount);
 		break;
 	case 'd':
 		if( termch != '\n' )
 			termch = 0;
 		scanhex((void *)&mdiffs);
-		memdiffs((unsigned char *)mdest, (unsigned char *)msrc, mcount, mdiffs);
+		memdiffs((unsigned char *)mdest, (unsigned char *)msrc,
+			 xmon_mcount, mdiffs);
 		break;
 	}
 }

Re: [patch 5/5] powerpc 2.6.21-rt1] fix clocksource_timebase.shift value

[Tsutomu OWA]

Calculate clocksource_timebase.shift from tb_ticks_per_jiffy to get an
accurate translation, though I don't understand why current version of 
clocksource_timebase.shift could be constant...

Signed-off-by: Tsutomu OWA <tsutomu.owa@toshiba.co.jp>
-- owa

--- linux-2.6.21-rt1/arch/powerpc/kernel/time.c	2007-05-09 18:05:57.000000000 +0900
+++ rt/arch/powerpc/kernel/time.c	2007-05-09 18:06:24.000000000 +0900
@@ -945,6 +945,9 @@ static int __init init_timebase_clocksou
 	if (__USE_RTC())
 		return -ENODEV;
 
+#ifdef CONFIG_PPC64
+	clocksource_timebase.shift = tb_ticks_per_jiffy / 1000000;
+#endif
 	clocksource_timebase.mult = clocksource_hz2mult(tb_ticks_per_sec,
 					clocksource_timebase.shift);
 	return clocksource_register(&clocksource_timebase);