Push a switchframe in dumpsys and cpu_switchto, but as dumpsys calls

other funcs a switchframe needs to be a multiple of 8 bytes. Stash sp as
well in the switchframe to bump it to 24bytes.

Setup the switchframe appropriately in cpu_lwp_fork.

Remove savectx - nothing uses it.

All of this make gdb's life much easier when dealing with crash dumps and
live kernels.

Reviewd by chris.

sys/arch/arm/arm32/cpuswitch.S

@@ -1,4 +1,4 @@
-/*	$NetBSD: cpuswitch.S,v 1.50 2007/10/17 19:53:30 garbled Exp $	*/
+/*	$NetBSD: cpuswitch.S,v 1.51 2008/01/12 20:50:23 skrll Exp $	*/
 
 /*
  * Copyright 2003 Wasabi Systems, Inc.
@@ -171,7 +171,8 @@ _C_LABEL(curpcb):
  *	r1	'struct lwp *' of the LWP to switch to
  */
 ENTRY(cpu_switchto)
-	stmfd	sp!, {r4-r7, lr}
+	mov	ip, sp
+	stmfd	sp!, {r4-r7, ip, lr}
 
 	mov	r6, r1		/* save new lwp */
 	mov	r4, r0		/* save old lwp, it's the return value */
@@ -347,10 +348,10 @@ ENTRY(cpu_switchto)
 	mov	r1, r6
 
 	/*
-	 * Pull the registers that got pushed when either savectx() or
+	 * Pull the registers that got pushed when cpu_switchto() was called,
-	 * cpu_switchto() was called and return.
+	 * and return.
 	 */
-	ldmfd	sp!, {r4-r7, pc}
+	ldmfd	sp, {r4-r7, sp, pc}
 
 .Lswitch_do_ras:
 	ldr	r1, [r1, #(TF_PC)]	/* second ras_lookup() arg */
@@ -361,29 +362,6 @@ ENTRY(cpu_switchto)
 	strne	r0, [r1, #(TF_PC)]
 	b	.Lswitch_return
 
-
-/* LINTSTUB: Func: void savectx(struct pcb *pcb) */
-ENTRY(savectx)
-	/*
-	 * r0 = pcb
-	 */
-
-	/* Push registers.*/
-	stmfd	sp!, {r4-r7, lr}
-
-	/* Store all the registers in the process's pcb */
-#ifndef __XSCALE__
-	add	r2, r0, #(PCB_R8)
-	stmia	r2, {r8-r13}
-#else
-	strd	r8, [r0, #(PCB_R8)]
-	strd	r10, [r0, #(PCB_R10)]
-	strd	r12, [r0, #(PCB_R12)]
-#endif
-
-	/* Pull the regs of the stack */
-	ldmfd	sp!, {r4-r7, pc}
-
 ENTRY(lwp_trampoline)
 	bl	_C_LABEL(lwp_startup)
 

sys/arch/arm/arm32/locore.S

@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.S,v 1.19 2008/01/01 14:06:42 chris Exp $	*/
+/*	$NetBSD: locore.S,v 1.20 2008/01/12 20:50:24 skrll Exp $	*/
 
 /*
  * Copyright (C) 1994-1997 Mark Brinicombe
@@ -218,11 +218,8 @@ ENTRY_NP(abort)
  */
 ENTRY(dumpsys)
 	/* push registers onto stack */
-	stmfd	sp!, {r0-r7, lr}
+	mov	ip, sp
-	
+	stmfd	sp!, {r4-r7, ip, lr}
-	/* push the status bits onto the stack */
-	mrs	r0, cpsr_all
-	stmfd	sp!, {r0}
 
 	/* fill in dumppcb */
 	ldr	r0, .Ldumppcb
@@ -239,9 +236,7 @@ ENTRY(dumpsys)
 	bl	_C_LABEL(dodumpsys)
 
 	/* unwind the stack */
-	ldmfd	sp!, {r0}
+	ldmfd	sp, {r4-r7, sp, pc}
-	nop
-	ldmfd	sp!, {r0-r7, pc}
 
 .Ldumppcb:
 	.word	_C_LABEL(dumppcb)

sys/arch/arm/arm32/vm_machdep.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: vm_machdep.c,v 1.40 2007/10/17 19:53:31 garbled Exp $	*/
+/*	$NetBSD: vm_machdep.c,v 1.41 2008/01/12 20:50:24 skrll Exp $	*/
 
 /*
  * Copyright (c) 1994-1998 Mark Brinicombe.
@@ -44,7 +44,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vm_machdep.c,v 1.40 2007/10/17 19:53:31 garbled Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vm_machdep.c,v 1.41 2008/01/12 20:50:24 skrll Exp $");
 
 #include "opt_armfpe.h"
 #include "opt_pmap_debug.h"
@@ -190,6 +190,7 @@ cpu_lwp_fork(struct lwp *l1, struct lwp *l2, void *stack, size_t stacksize,
 	sf = (struct switchframe *)tf - 1;
 	sf->sf_r4 = (u_int)func;
 	sf->sf_r5 = (u_int)arg;
+	sf->sf_sp = (u_int)tf;
 	sf->sf_pc = (u_int)lwp_trampoline;
 	pcb->pcb_un.un_32.pcb32_sp = (u_int)sf;
 }

sys/arch/arm/include/arm32/frame.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: frame.h,v 1.15 2007/03/09 19:21:58 thorpej Exp $	*/
+/*	$NetBSD: frame.h,v 1.16 2008/01/12 20:50:24 skrll Exp $	*/
 
 /*
  * Copyright (c) 1994-1997 Mark Brinicombe.
@@ -81,7 +81,9 @@ struct clockframe {
 };
 
 /*
- * Switch frame
+ * Switch frame.
+ *
+ * Should be a multiple of 8 bytes for dumpsys.
  */
 
 struct switchframe {
@@ -89,6 +91,7 @@ struct switchframe {
 	u_int	sf_r5;
 	u_int	sf_r6;
 	u_int	sf_r7;
+	u_int	sf_sp;
 	u_int	sf_pc;
 };