Add user-space profiling support. Kernel profiling still todo.

Obtained from:	NetBSD

sys/powerpc/include/profile.h

@@ -32,22 +32,96 @@
 #ifndef _MACHINE_PROFILE_H_
 #define	_MACHINE_PROFILE_H_
 
-#define	_MCOUNT_DECL	void mcount
+#define	_MCOUNT_DECL	void __mcount
 
 #define FUNCTION_ALIGNMENT 16
 
 typedef u_int	fptrdiff_t;
 
+/*
+ * The mcount trampoline macro, expanded in libc/gmon/mcount.c
+ *
+ * For PowerPC SVR4 ABI profiling, the compiler will insert
+ * a data declaration and code sequence at the start of a routine of the form
+ *
+ * .function_mc:       	.data
+ *			.align	2
+ *			.long	0
+ *			.text
+ *
+ * function:		mflr	%r0
+ *			addis	%r11,%r0, .function_mc@ha
+ *			stw	%r0,4(%r1)
+ *			addi	%r0,%r11, .function_mc@l
+ *			bl	_mcount
+ *
+ * The link register is saved in the LR save word in the caller's
+ * stack frame, r0 is set up to point to the allocated longword,
+ * and control is transferred to _mcount.
+ *
+ * On return from _mcount, the routine should function as it would
+ * with no profiling so _mcount must restore register state to that upon
+ * entry. Any routine called by the _mcount trampoline will save
+ * callee-save registers, so _mcount must make sure it saves volatile
+ * registers that may have state after it returns i.e. parameter registers.
+ *
+ * The FreeBSD libc mcount routine ignores the r0 longword pointer, but
+ * instead requires as parameters the current PC and called PC. The current
+ * PC is obtained from the link register, as a result of "bl _mcount" in
+ * the stub, while the caller's PC is obtained from the LR save word.
+ *
+ * On return from libc mcount, the return is done indirectly with the
+ * ctr register rather than the link register, to allow the link register
+ * to be restored to what it was on entry to the profiled routine.
+ */
+
+#ifdef PIC
+#define _PLT "@plt"
+#else
+#define _PLT
+#endif
+
 #define	MCOUNT \
-void \
-_mcount() \
-{ \
-}
+__asm("	.globl	_mcount						\n" \
+"	.type	_mcount,@function				\n" \
+"_mcount:							\n" \
+"	stwu	%r1,-64(%r1)	/* alloca for reg save space */	\n" \
+"	stw	%r3,16(%r1)	/* save parameter registers, */	\n" \
+"	stw	%r4,20(%r1)    	/*  r3-10		     */	\n" \
+"	stw	%r5,24(%r1)	       				\n" \
+"	stw	%r6,28(%r1)	       				\n" \
+"	stw	%r7,32(%r1)	       				\n" \
+"	stw	%r8,36(%r1)	       				\n" \
+"	stw	%r9,40(%r1)	       				\n" \
+"	stw	%r10,44(%r1)					\n" \
+"								\n" \
+"	mflr	%r4		/* link register is 'selfpc' */	\n" \
+"	stw	%r4,48(%r1)    	/* save since bl will scrub  */	\n" \
+"	lwz	%r3,68(%r1)    	/* get 'frompc' from LR-save */	\n" \
+"	bl	__mcount" _PLT "  /* __mcount(frompc, selfpc)*/	\n" \
+"	lwz	%r3,68(%r1)					\n" \
+"	mtlr	%r3		/* restore caller's lr	     */	\n" \
+"	lwz	%r4,48(%r1)     			       	\n" \
+"	mtctr	%r4		/* set up ctr for call back  */	\n" \
+"				/* note that blr is not used!*/	\n" \
+"	lwz	%r3,16(%r1)	/* restore r3-10 parameters  */	\n" \
+"	lwz	%r4,20(%r1)	       				\n" \
+"	lwz	%r5,24(%r1)	       				\n" \
+"	lwz	%r6,28(%r1)	       				\n" \
+"	lwz	%r7,32(%r1)	       				\n" \
+"	lwz	%r8,36(%r1)	       				\n" \
+"	lwz	%r9,40(%r1)	       				\n" \
+"	lwz	%r10,44(%r1)					\n" \
+"	addi	%r1,%r1,64	/* blow away alloca save area */ \n" \
+"	bctr			/* return with indirect call */	\n" \
+"_mcount_end:				\n" \
+"	.size	_mcount,_mcount_end-_mcount");
+
 
 #ifdef _KERNEL
-#define MCOUNT_ENTER(s)
-#define MCOUNT_EXIT(s)
-#define	MCOUNT_DECL(s)
+#define MCOUNT_ENTER(s)		s = intr_disable();
+#define MCOUNT_EXIT(s)		intr_restore(s);
+#define	MCOUNT_DECL(s)		register_t s
 
 void bintr(void);
 void btrap(void);