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

[Tsutomu OWA <tsutomu.owa@toshiba.co.jp>]

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 */

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