Make the OpenFirmware functions work with clang.

ofw_stack() was changing its caller's stack frame, but this stops
working when clang inlines the caller into another function.  Move the
stack-switching logic into openfirmware().  Now ofw_stack() becomes
ofw_msr() and only sets the msr.

ok deraadt@ kettenis@

sys/arch/macppc/macppc/ofw_machdep.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ofw_machdep.h,v 1.9 2015/04/07 14:36:34 mpi Exp $	*/
+/*	$OpenBSD: ofw_machdep.h,v 1.10 2020/04/02 19:27:51 gkoehler Exp $	*/
 
 /*
  * Copyright (c) 2002, Miodrag Vallat.
@@ -26,6 +26,9 @@
  *
  */
 
+#include <machine/cpu.h>
+#include <machine/psl.h>
+
 extern int cons_backlight_available;
 
 void ofwconprobe(void);
@@ -49,3 +52,12 @@ void of_setbrightness(int);
 void of_setcolors(const uint8_t *, unsigned int, unsigned int);
 
 void OF_quiesce(void);
+
+static inline uint32_t
+ofw_msr(void)
+{
+	uint32_t s = ppc_mfmsr();
+
+	ppc_mtmsr(s & ~(PSL_EE|PSL_RI)); /* turn off interrupts */
+	return s;
+}

sys/arch/macppc/macppc/ofwreal.S

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ofwreal.S,v 1.5 2019/09/03 14:37:22 deraadt Exp $	*/
+/*	$OpenBSD: ofwreal.S,v 1.6 2020/04/02 19:27:51 gkoehler Exp $	*/
 /*	$NetBSD: ofwreal.S,v 1.1 1996/09/30 16:34:51 ws Exp $	*/
 
 /*
@@ -355,96 +355,32 @@ _ENTRY(_C_LABEL(fwentry))
 	addi	%r1,%r1,16
 	blr
 
+.lcomm	firmstk,NBPG,16
+.comm	_C_LABEL(OF_buf),NBPG
+
 /*
  * OpenFirmware entry point
+ *
+ * Note: caller has to set the machine state register (msr)
+ * to be correct for OpenFirmware.
  */
 _ENTRY(_C_LABEL(openfirmware))
-	stwu	%r1,-16(%r1)
-	mflr	%r0			/* save return address */
-	stw	%r0,20(%r1)
+	mflr	%r0
+	stw	%r0,4(%r1)		/* save return address */
+
+	/* switch to OpenFirmware real mode stack */
+	lis	%r7,firmstk+NBPG-16@ha
+	addi	%r7,%r7,firmstk+NBPG-16@l
+	stw	%r1,0(%r7)
+	mr	%r1,%r7
 
 	lis	%r4,fwcall@ha
 	lwz	%r4,fwcall@l(%r4)
 
-	mtlr	%r4
-	blrl
+	mtctr	%r4
+	bctrl
 
-	lwz	%r0,20(%r1)
-	mtlr	%r0
-	lwz	%r1,0(%r1)
-	blr
-
-/*
- * Switch to/from OpenFirmware real mode stack
- *
- * Note: has to be called as the very first thing in OpenFirmware interface routines.
- * E.g.:
- * int
- * OF_xxx(arg1, arg2)
- * type arg1, arg2;
- * {
- *	static struct {
- *		char *name;
- *		int nargs;
- *		int nreturns;
- *		char *method;
- *		int arg1;
- *		int arg2;
- *		int ret;
- *	} args = {
- *		"xxx",
- *		2,
- *		1,
- *	};
- *
- *	ofw_stack();
- *	args.arg1 = arg1;
- *	args.arg2 = arg2;
- *	if (openfirmware(&args) < 0)
- *		return -1;
- *	return args.ret;
- * }
- */
-.lcomm	firmstk,NBPG,16
-.comm	_C_LABEL(OF_buf),NBPG
-
-_ENTRY(_C_LABEL(ofw_stack))
-	mfmsr	%r8			/* turn off interrupts */
-	andi.	%r0,%r8,~(PSL_EE|PSL_RI)@l
-	mtmsr	%r0
-	stw	%r8,4(%r1)		/* abuse return address slot */
-
-	lwz	%r5,0(%r1)		/* get length of stack frame */
-	subf	%r5,%r1,%r5
-
-	lis	%r7,firmstk+NBPG-8@ha
-	addi	%r7,%r7,firmstk+NBPG-8@l
-	li	%r6,0xf
-	andc	%r7,%r7,%r6
-	lis	%r6,ofw_back@ha
-	addi	%r6,%r6,ofw_back@l
-	subf	%r4,%r5,%r7		/* make room for stack frame on new stack */
-	stwu	%r1,-16(%r7)
-	stw	%r6,4(%r7)		/* setup return pointer */
-
-	stw	%r7,-16(%r4)
-
-	addi	%r3,%r1,%r8
-	addi	%r1,%r4,-16
-	subi	%r5,%r5,%r8
-	subi	%r4,%r4,%r8
-
-	b	_C_LABEL(ofbcopy)	/* and copy it */
-
-	.type ofw_back,@function
-ofw_back:
 	lwz	%r1,0(%r1)		/* get callers original stack pointer */
-
-	lwz	%r0,4(%r1)		/* get saved msr from abused slot */
-	mtmsr	%r0
-
-	lwz	%r1,0(%r1)		/* return */
 	lwz	%r0,4(%r1)
 	mtlr	%r0
 	blr
-

sys/arch/macppc/macppc/opendev.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: opendev.c,v 1.9 2006/03/09 23:06:19 miod Exp $	*/
+/*	$OpenBSD: opendev.c,v 1.10 2020/04/02 19:27:51 gkoehler Exp $	*/
 /*	$NetBSD: openfirm.c,v 1.1 1996/09/30 16:34:52 ws Exp $	*/
 
 /*
@@ -34,11 +34,12 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/stdarg.h>
+#include <machine/cpu.h>
 #include <machine/psl.h>
 
 #include <dev/ofw/openfirm.h>
+#include "ofw_machdep.h"
 
-extern void ofw_stack(void);
 extern void ofbcopy(const void *, void *, size_t);
 
 int
@@ -55,12 +56,17 @@ OF_instance_to_package(int ihandle)
 		1,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.ihandle = ihandle;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.phandle;
+		ret = -1;
+	else
+		ret = args.phandle;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -79,18 +85,24 @@ OF_package_to_path(int phandle, char *buf, int buflen)
 		3,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
 	if (buflen > PAGE_SIZE)
 		return -1;
+	s = ofw_msr();
 	args.phandle = phandle;
 	args.buf = OF_buf;
 	args.buflen = buflen;
 	if (openfirmware(&args) < 0)
-		return -1;
-	if (args.length > 0)
-		ofbcopy(OF_buf, buf, args.length);
-	return args.length;
+		ret = -1;
+	else {
+		if (args.length > 0)
+			ofbcopy(OF_buf, buf, args.length);
+		ret = args.length;
+	}
+	ppc_mtmsr(s);
+	return ret;
 }
 
 
@@ -110,10 +122,12 @@ OF_call_method(char *method, int ihandle, int nargs, int nreturns, ...)
 		2,
 		1,
 	};
-	int *ip, n;
+	uint32_t s;
+	int *ip, n, ret;
 
 	if (nargs > 6)
 		return -1;
+	s = ofw_msr();
 	args.nargs = nargs + 2;
 	args.nreturns = nreturns + 1;
 	args.method = method;
@@ -121,19 +135,19 @@ OF_call_method(char *method, int ihandle, int nargs, int nreturns, ...)
 	va_start(ap, nreturns);
 	for (ip = args.args_n_results + (n = nargs); --n >= 0;)
 		*--ip = va_arg(ap, int);
-	ofw_stack();
-	if (openfirmware(&args) == -1) {
-		va_end(ap);
-		return -1;
+	if (openfirmware(&args) == -1)
+		ret = -1;
+	else if (args.args_n_results[nargs])
+		ret = args.args_n_results[nargs];
+	else {
+		for (ip = args.args_n_results + nargs + (n = args.nreturns);
+		    --n > 0;)
+			*va_arg(ap, int *) = *--ip;
+		ret = 0;
 	}
-	if (args.args_n_results[nargs]) {
-		va_end(ap);
-		return args.args_n_results[nargs];
-	}
-	for (ip = args.args_n_results + nargs + (n = args.nreturns); --n > 0;)
-		*va_arg(ap, int *) = *--ip;
 	va_end(ap);
-	return 0;
+	ppc_mtmsr(s);
+	return ret;
 }
 int
 OF_call_method_1(char *method, int ihandle, int nargs, ...)
@@ -151,10 +165,12 @@ OF_call_method_1(char *method, int ihandle, int nargs, ...)
 		2,
 		2,
 	};
-	int *ip, n;
+	uint32_t s;
+	int *ip, n, ret;
 
 	if (nargs > 6)
 		return -1;
+	s = ofw_msr();
 	args.nargs = nargs + 2;
 	args.method = method;
 	args.ihandle = ihandle;
@@ -162,12 +178,14 @@ OF_call_method_1(char *method, int ihandle, int nargs, ...)
 	for (ip = args.args_n_results + (n = nargs); --n >= 0;)
 		*--ip = va_arg(ap, int);
 	va_end(ap);
-	ofw_stack();
 	if (openfirmware(&args) == -1)
-		return -1;
-	if (args.args_n_results[nargs])
-		return -1;
-	return args.args_n_results[nargs + 1];
+		ret = -1;
+	else if (args.args_n_results[nargs])
+		ret = -1;
+	else
+		ret = args.args_n_results[nargs + 1];
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -184,16 +202,20 @@ OF_open(char *dname)
 		1,
 		1,
 	};
-	int l;
+	uint32_t s;
+	int l, ret;
 
-	ofw_stack();
 	if ((l = strlen(dname)) >= PAGE_SIZE)
 		return -1;
+	s = ofw_msr();
 	ofbcopy(dname, OF_buf, l + 1);
 	args.dname = OF_buf;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.handle;
+		ret = -1;
+	else
+		ret = args.handle;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 void
@@ -209,10 +231,12 @@ OF_close(int handle)
 		1,
 		0,
 	};
+	uint32_t s;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.handle = handle;
 	openfirmware(&args);
+	ppc_mtmsr(s);
 }
 
 /*
@@ -234,28 +258,35 @@ OF_read(int handle, void *addr, int len)
 		3,
 		1,
 	};
-	int l, act = 0;
+	uint32_t s;
+	int act = 0, l, ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.ihandle = handle;
 	args.addr = OF_buf;
 	for (; len > 0; len -= l, addr += l) {
 		l = min(PAGE_SIZE, len);
 		args.len = l;
-		if (openfirmware(&args) == -1)
-			return -1;
+		if (openfirmware(&args) == -1) {
+			ret = -1;
+			goto out;
+		}
 		if (args.actual > 0) {
 			ofbcopy(OF_buf, addr, args.actual);
 			act += args.actual;
 		}
 		if (args.actual < l) {
 			if (act)
-				return act;
+				ret = act;
 			else
-				return args.actual;
+				ret = args.actual;
+			goto out;
 		}
 	}
-	return act;
+	ret = act;
+out:
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -274,21 +305,27 @@ OF_write(int handle, void *addr, int len)
 		3,
 		1,
 	};
-	int l, act = 0;
+	uint32_t s;
+	int act = 0, l, ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.ihandle = handle;
 	args.addr = OF_buf;
 	for (; len > 0; len -= l, addr += l) {
 		l = min(PAGE_SIZE, len);
 		ofbcopy(addr, OF_buf, l);
 		args.len = l;
-		if (openfirmware(&args) == -1)
-			return -1;
+		if (openfirmware(&args) == -1) {
+			ret = -1;
+			goto out;
+		}
 		l = args.actual;
 		act += l;
 	}
-	return act;
+	ret = act;
+out:
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -307,12 +344,17 @@ OF_seek(int handle, u_quad_t pos)
 		3,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.handle = handle;
 	args.poshi = (int)(pos >> 32);
 	args.poslo = (int)pos;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.status;
+		ret = -1;
+	else
+		ret = args.status;
+	ppc_mtmsr(s);
+	return ret;
 }

sys/arch/macppc/macppc/openfirm.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: openfirm.c,v 1.12 2019/09/03 17:51:52 deraadt Exp $	*/
+/*	$OpenBSD: openfirm.c,v 1.13 2020/04/02 19:27:51 gkoehler Exp $	*/
 /*	$NetBSD: openfirm.c,v 1.1 1996/09/30 16:34:52 ws Exp $	*/
 
 /*
@@ -34,11 +34,12 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/stdarg.h>
+#include <machine/cpu.h>
 #include <machine/psl.h>
 
 #include <dev/ofw/openfirm.h>
+#include "ofw_machdep.h"
 
-extern void ofw_stack(void);
 extern void ofbcopy(const void *, void *, size_t);
 
 int
@@ -55,12 +56,17 @@ OF_peer(int phandle)
 		1,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.phandle = phandle;
 	if (openfirmware(&args) == -1)
-		return 0;
-	return args.sibling;
+		ret = 0;
+	else
+		ret = args.sibling;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -77,12 +83,17 @@ OF_child(int phandle)
 		1,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.phandle = phandle;
 	if (openfirmware(&args) == -1)
-		return 0;
-	return args.child;
+		ret = 0;
+	else
+		ret = args.child;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -99,12 +110,17 @@ OF_parent(int phandle)
 		1,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.phandle = phandle;
 	if (openfirmware(&args) == -1)
-		return 0;
-	return args.parent;
+		ret = 0;
+	else
+		ret = args.parent;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -122,13 +138,18 @@ OF_getproplen(int handle, char *prop)
 		2,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.phandle = handle;
 	args.prop = prop;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.size;
+		ret = -1;
+	else
+		ret = args.size;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -148,19 +169,25 @@ OF_getprop(int handle, char *prop, void *buf, int buflen)
 		4,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
 	if (buflen > NBPG)
 		return -1;
+	s = ofw_msr();
 	args.phandle = handle;
 	args.prop = prop;
 	args.buf = OF_buf;
 	args.buflen = buflen;
 	if (openfirmware(&args) == -1)
-		return -1;
-	if (args.size > 0)
-		ofbcopy(OF_buf, buf, args.size);
-	return args.size;
+		ret = -1;
+	else {
+		if (args.size > 0)
+			ofbcopy(OF_buf, buf, args.size);
+		ret = args.size;
+	}
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -180,18 +207,23 @@ OF_setprop(int handle, char *prop, const void *buf, int buflen)
 		4,
 		1,
 	};
+	uint32_t s;
+	int ret;
 	
-	ofw_stack();
 	if (buflen > NBPG)
 		return -1;
+	s = ofw_msr();
 	args.phandle = handle;
 	args.prop = prop;
 	ofbcopy(buf, OF_buf, buflen);
 	args.buf = OF_buf;
 	args.buflen = buflen;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.size;
+		ret = -1;
+	else
+		ret = args.size;
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
@@ -210,22 +242,27 @@ OF_nextprop(int handle, char *prop, void *nextprop)
 		3,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.phandle = handle;
 	args.prop = prop;
 	args.buf = OF_buf;
 	if (openfirmware(&args) == -1)
-		return -1;
-	strlcpy(nextprop, OF_buf, 32);
-	return args.flag;
+		ret = -1;
+	else {
+		strlcpy(nextprop, OF_buf, 32);
+		ret = args.flag;
+	}
+	ppc_mtmsr(s);
+	return ret;
 }
 
 int
 OF_interpret(char *cmd, int nreturns, ...)
 {
 	va_list ap;
-	int i;
 	static struct {
 		char *name;
 		int nargs;
@@ -238,23 +275,29 @@ OF_interpret(char *cmd, int nreturns, ...)
 		1,
 		2,
 	};
+	uint32_t s;
+	int i, ret;
 
-	ofw_stack();
 	if (nreturns > 8)
 		return -1;
 	if ((i = strlen(cmd)) >= NBPG)
 		return -1;
+	s = ofw_msr();
 	ofbcopy(cmd, OF_buf, i + 1);
 	args.cmd = OF_buf;
 	args.nargs = 1;
 	args.nreturns = nreturns + 1;
 	if (openfirmware(&args) == -1)
-		return -1;
-	va_start(ap, nreturns);
-	for (i = 0; i < nreturns; i++)
-		*va_arg(ap, int *) = args.results[i];
-	va_end(ap);
-	return args.status;
+		ret = -1;
+	else {
+		va_start(ap, nreturns);
+		for (i = 0; i < nreturns; i++)
+			*va_arg(ap, int *) = args.results[i];
+		va_end(ap);
+		ret = args.status;
+	}
+	ppc_mtmsr(s);
+	return ret;
 }
 
 
@@ -272,12 +315,17 @@ OF_finddevice(char *name)
 		1,
 		1,
 	};
+	uint32_t s;
+	int ret;
 
-	ofw_stack();
+	s = ofw_msr();
 	args.device = name;
 	if (openfirmware(&args) == -1)
-		return -1;
-	return args.phandle;
+		ret = -1;
+	else
+		ret = args.phandle;
+	ppc_mtmsr(s);
+	return ret;
 }
 static void OF_rboot(char *bootspec);
 
@@ -293,12 +341,14 @@ OF_rboot(char *bootspec)
 		0,
 		0,
 	};
+	uint32_t s;
 	int l;
 
 	if ((l = strlen(bootspec)) >= NBPG)
 		panic("OF_boot");
-	ofw_stack();
+	s = ofw_msr();
 	openfirmware(&args);
+	ppc_mtmsr(s);
 	/* will attempt exit in OF_boot */
 }
 
@@ -325,7 +375,7 @@ OF_exit(void)
 		0,
 	};
 
-	ofw_stack();
+	ofw_msr();
 	openfirmware(&args);
 	panic ("OF_exit returned!");		/* just in case */
 	while (1);
@@ -343,9 +393,11 @@ OF_quiesce(void)
 		0,
 		0,
 	};
+	uint32_t s;
 
-	ofw_stack();
+	s = ofw_msr();
 	openfirmware(&args);
+	ppc_mtmsr(s);
 }
 
 /* XXX What is the reason to have this instead of bcopy/memcpy? */