PERFORCE change 28595 for review

[Marcel Moolenaar]

http://perforce.freebsd.org/chv.cgi?CH=28595

Change 28595 by marcel at marcel_nfs on 2003/04/08 19:03:47

	Move fork_trampoline from context.s to locore.s and break
	where we used to jump to exception_restore. We cannot go
	to exception_restore, because fork(2) will have a syscall
	frame instead of a trap frame. Hence, we must go to user
	space in a way that works with the EPC syscall path. This
	has to be determined.

Affected files ...

.. //depot/projects/ia64_epc/sys/ia64/ia64/context.s#8 edit
.. //depot/projects/ia64_epc/sys/ia64/ia64/locore.s#6 edit

Differences ...

==== //depot/projects/ia64_epc/sys/ia64/ia64/context.s#8 (text+ko) ====

@@ -302,35 +302,6 @@
 END(swapctx)
 
 /*
- * fork_trampoline()
- *
- * Arrange for a function to be invoked neatly, after a cpu_switch().
- *
- * Invokes fork_exit() passing in three arguments: a callout function, an
- * argument to the callout, and a trapframe pointer.  For child processes
- * returning from fork(2), the argument is a pointer to the child process.
- *
- * The callout function is in r4, the address to return to after executing
- * fork_exit() is in r5, and the argument is in r6.
- */
-ENTRY(fork_trampoline, 0)
-	.prologue
-	.save	rp,r0
-	.body
-	alloc	r14=ar.pfs,0,0,3,0
-	;;
-	mov	b0=r5
-	mov	out0=r4
-	mov	out1=r6
-	add	out2=16,sp
-	;;
-	br.call.sptk.few rp=fork_exit
-	;; 
-	br.cond.sptk.many exception_restore
-	;;
-END(fork_trampoline)
-
-/*
  * _getcontext(ucontext_t *ucp)
  */
 ENTRY(_getcontext, 1)

==== //depot/projects/ia64_epc/sys/ia64/ia64/locore.s#6 (text+ko) ====

@@ -141,6 +141,38 @@
 
 END(mi_startup_trampoline)
 
+/*
+ * fork_trampoline()
+ *
+ * Arrange for a function to be invoked neatly, after a cpu_switch().
+ *
+ * Invokes fork_exit() passing in three arguments: a callout function, an
+ * argument to the callout, and a trapframe pointer.  For child processes
+ * returning from fork(2), the argument is a pointer to the child process.
+ *
+ * The callout function is in r4 and the argument is in r6.
+ */
+ENTRY(fork_trampoline, 0)
+	.prologue
+	.save	rp,r0
+	.body
+{	.mmi
+	alloc		r14=ar.pfs,0,0,3,0
+	mov		out0=r4
+	mov		out1=r6
+	;;
+}
+{	.mfb
+	add		out2=16,sp
+	nop		0
+	br.call.sptk	rp=fork_exit
+	;;
+}
+	// If we get back here, it means we're a user space process that's
+	// the immediate result of fork(2).
+	break		0
+END(fork_trampoline)
+
 #ifdef SMP
 /*
  * AP wake-up entry point. The handoff state is similar as for the BSP,