kernel: get rid of Proc.kstack

The kernel stack is now above the Proc structure,
so the explicit kstack pointer can be eliminated.

31 files changed, 87 insertions, 97 deletions

diff --git a/sys/src/9/bcm/arch.c b/sys/src/9/bcm/arch.c
index fb97a3ea9..a025fe371 100644
--- a/sys/src/9/bcm/arch.c
+++ b/sys/src/9/bcm/arch.c
@@ -68,7 +68,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr)entry;
-	p->sched.sp = (uintptr)p->kstack+KSTACK;
+	p->sched.sp = (uintptr)p;
 }
 
 /*
diff --git a/sys/src/9/bcm/trap.c b/sys/src/9/bcm/trap.c
index 4aa44fdbe..01008650b 100644
--- a/sys/src/9/bcm/trap.c
+++ b/sys/src/9/bcm/trap.c
@@ -138,7 +138,7 @@ trap(Ureg *ureg)
 
 	assert(!islo());
 	if(up != nil)
-		rem = ((char*)ureg)-up->kstack;
+		rem = ((char*)ureg)-((char*)up - KSTACK);
 	else
 		rem = ((char*)ureg)-((char*)m+sizeof(Mach));
 	if(rem < 256) {
@@ -343,14 +343,14 @@ dumpstackwithureg(Ureg *ureg)
 		ureg->pc, ureg->sp, ureg->r14);
 	delay(2000);
 	i = 0;
-	if(up != nil && (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	if(up != nil && (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	     && (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
 	else{
 		if(up != nil)
-			iprint("&up->kstack %#p &l %#p\n", up->kstack, &l);
+			iprint("&up %#p &l %#p\n", up, &l);
 		else
 			iprint("&m %#p &l %#p\n", m, &l);
 		return;
@@ -420,10 +420,9 @@ dumpregs(Ureg* ureg)
 	iprint("pc %#lux link %#lux\n", ureg->pc, ureg->link);
 
 	if(up)
-		iprint("user stack: %#p-%#p\n", up->kstack, up->kstack+KSTACK-4);
+		iprint("user stack: %#p-%#p\n", (char*)up - KSTACK, up);
 	else
-		iprint("kernel stack: %8.8lux-%8.8lux\n",
-			(ulong)(m+1), (ulong)m+BY2PG-4);
+		iprint("kernel stack: %8.8lux-%8.8lux\n", (ulong)(m+1), (ulong)m+BY2PG);
 	dumplongs("stack", (ulong *)(ureg + 1), 16);
 	delay(2000);
 	dumpstack();
diff --git a/sys/src/9/bcm64/trap.c b/sys/src/9/bcm64/trap.c
index d3dedb8f9..60f7d1937 100644
--- a/sys/src/9/bcm64/trap.c
+++ b/sys/src/9/bcm64/trap.c
@@ -566,7 +566,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr) entry;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - 16;
+	p->sched.sp = (uintptr) p - 16;
 	*(void**)p->sched.sp = kprocchild;	/* fake */
 }
 
@@ -576,7 +576,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 	p->sched.pc = (uintptr) forkret;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - TRAPFRAMESIZE;
+	p->sched.sp = (uintptr) p - TRAPFRAMESIZE;
 
 	cureg = (Ureg*) (p->sched.sp + 16);
 	memmove(cureg, ureg, sizeof(Ureg));
@@ -661,12 +661,12 @@ dumpstackwithureg(Ureg *ureg)
 		sp = (uintptr)&ureg;
 
 	estack = (uintptr)m+MACHSIZE;
-	if(up != nil && sp <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	if(up != nil && sp <= (uintptr)up)
+		estack = (uintptr)up;
 
 	if(sp > estack){
 		if(up != nil)
-			iprint("&up->kstack %#p sp %#p\n", up->kstack, sp);
+			iprint("&up %#p sp %#p\n", up, sp);
 		else
 			iprint("&m %#p sp %#p\n", m, sp);
 		return;
diff --git a/sys/src/9/cycv/trap.c b/sys/src/9/cycv/trap.c
index a47238cc3..98fb56715 100644
--- a/sys/src/9/cycv/trap.c
+++ b/sys/src/9/cycv/trap.c
@@ -26,9 +26,9 @@ _dumpstack(Ureg *ureg)
 	x += iprint("ktrace /arm/9cycv %.8lux %.8lux %.8lux <<EOF\n", ureg->pc, ureg->sp, ureg->r14);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
@@ -522,7 +522,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr) entry;
-	p->sched.sp = (uintptr) p->kstack + KSTACK;
+	p->sched.sp = (uintptr) p;
 }
 
 void
@@ -531,7 +531,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 	p->sched.pc = (uintptr) forkret;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - sizeof(Ureg);
+	p->sched.sp = (uintptr) p - sizeof(Ureg);
 
 	cureg = (Ureg*) p->sched.sp;
 	memmove(cureg, ureg, sizeof(Ureg));
diff --git a/sys/src/9/imx8/trap.c b/sys/src/9/imx8/trap.c
index d3dedb8f9..60f7d1937 100644
--- a/sys/src/9/imx8/trap.c
+++ b/sys/src/9/imx8/trap.c
@@ -566,7 +566,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr) entry;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - 16;
+	p->sched.sp = (uintptr) p - 16;
 	*(void**)p->sched.sp = kprocchild;	/* fake */
 }
 
@@ -576,7 +576,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 	p->sched.pc = (uintptr) forkret;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - TRAPFRAMESIZE;
+	p->sched.sp = (uintptr) p - TRAPFRAMESIZE;
 
 	cureg = (Ureg*) (p->sched.sp + 16);
 	memmove(cureg, ureg, sizeof(Ureg));
@@ -661,12 +661,12 @@ dumpstackwithureg(Ureg *ureg)
 		sp = (uintptr)&ureg;
 
 	estack = (uintptr)m+MACHSIZE;
-	if(up != nil && sp <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	if(up != nil && sp <= (uintptr)up)
+		estack = (uintptr)up;
 
 	if(sp > estack){
 		if(up != nil)
-			iprint("&up->kstack %#p sp %#p\n", up->kstack, sp);
+			iprint("&up %#p sp %#p\n", up, sp);
 		else
 			iprint("&m %#p sp %#p\n", m, sp);
 		return;
diff --git a/sys/src/9/kw/arch.c b/sys/src/9/kw/arch.c
index 8f73da606..2395c74ea 100644
--- a/sys/src/9/kw/arch.c
+++ b/sys/src/9/kw/arch.c
@@ -68,7 +68,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr)entry;
-	p->sched.sp = (uintptr)p->kstack+KSTACK;
+	p->sched.sp = (uintptr)p;
 }
 
 /*
diff --git a/sys/src/9/kw/syscall.c b/sys/src/9/kw/syscall.c
index 067c4a48b..521f519c1 100644
--- a/sys/src/9/kw/syscall.c
+++ b/sys/src/9/kw/syscall.c
@@ -314,7 +314,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 //print("%lud setting up for forking child %lud\n", up->pid, p->pid);
-	p->sched.sp = (ulong)p->kstack+KSTACK-sizeof(Ureg);
+	p->sched.sp = (ulong)p-sizeof(Ureg);
 	p->sched.pc = (ulong)forkret;
 
 	cureg = (Ureg*)(p->sched.sp);
diff --git a/sys/src/9/kw/trap.c b/sys/src/9/kw/trap.c
index 1b0705b05..dafc8fc42 100644
--- a/sys/src/9/kw/trap.c
+++ b/sys/src/9/kw/trap.c
@@ -367,7 +367,7 @@ trap(Ureg *ureg)
 	char buf[ERRMAX];
 
 	if(up != nil)
-		rem = (char*)ureg - up->kstack;
+		rem = (char*)ureg - ((char*)up - KSTACK);
 	else
 		rem = (char*)ureg - ((char*)m + sizeof(Mach));
 	if(rem < 256) {
@@ -540,14 +540,14 @@ dumpstackwithureg(Ureg *ureg)
 		ureg->pc, ureg->sp, ureg->r14);
 	delay(2000);
 	i = 0;
-	if(up != nil && (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	if(up != nil && (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	     && (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
 	else{
 		if(up != nil)
-			iprint("&up->kstack %#p &l %#p\n", up->kstack, &l);
+			iprint("&up %#p &l %#p\n", up, &l);
 		else
 			iprint("&m %#p &l %#p\n", m, &l);
 		return;
@@ -617,10 +617,9 @@ dumpregs(Ureg* ureg)
 	iprint("pc %#lux link %#lux\n", ureg->pc, ureg->link);
 
 	if(up)
-		iprint("user stack: %#p-%#p\n", up->kstack, up->kstack+KSTACK-4);
+		iprint("user stack: %#p-%#p\n", (char*)up - KSTACK, up);
 	else
-		iprint("kernel stack: %8.8lux-%8.8lux\n",
-			(ulong)(m+1), (ulong)m+BY2PG-4);
+		iprint("kernel stack: %8.8lux-%8.8lux\n", (ulong)(m+1), (ulong)m+BY2PG);
 	dumplongs("stack", (ulong *)(ureg + 1), 16);
 	delay(2000);
 	dumpstack();
diff --git a/sys/src/9/mtx/l.s b/sys/src/9/mtx/l.s
index 25e8b4b50..1c07553ee 100644
--- a/sys/src/9/mtx/l.s
+++ b/sys/src/9/mtx/l.s
@@ -412,9 +412,7 @@ TEXT	trapvec(SB), $-4
 	RLWNM	$0, R1, $~KZERO, R1		/* PADDR(m->) */
 	MOVW	8(R1), R1				/* m->proc  */
 	RLWNM	$0, R1, $~KZERO, R1		/* PADDR(m->proc) */
-	MOVW	8(R1), R1				/* m->proc->kstack */
-	RLWNM	$0, R1, $~KZERO, R1		/* PADDR(m->proc->kstack) */
-	ADD	$(KSTACK-UREGSIZE), R1
+	SUB	$UREGSIZE, R1			/* make room on stack */
 	MOVW	R0, R2
 	BL	saveureg(SB)
 	BL	trap(SB)
diff --git a/sys/src/9/mtx/trap.c b/sys/src/9/mtx/trap.c
index d82b802c4..962401dd4 100644
--- a/sys/src/9/mtx/trap.c
+++ b/sys/src/9/mtx/trap.c
@@ -450,8 +450,8 @@ _dumpstack(Ureg *ureg)
 		sl = el-KSTACK;
 	}
 	else{
-		sl = (ulong)up->kstack;
-		el = sl + KSTACK;
+		el = (ulong)up;
+		sl = el-KSTACK;
 	}
 	if(l > el || l < sl){
 		el = (ulong)m+BY2PG;
@@ -488,7 +488,7 @@ dumpregs(Ureg *ur)
 	if(up) {
 		print("registers for %s %ld\n", up->text, up->pid);
 		if((ur->srr1 & MSR_PR) == 0)
-		if(ur->usp < (ulong)up->kstack || ur->usp > (ulong)up->kstack+KSTACK)
+		if(ur->usp < (ulong)up - KSTACK || ur->usp > (ulong)up)
 			print("invalid stack ptr\n");
 	}
 	else
@@ -504,7 +504,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (ulong)entry;
-	p->sched.sp = (ulong)p->kstack+KSTACK;
+	p->sched.sp = (ulong)p;
 }
 
 /*
@@ -540,7 +540,7 @@ forkchild(Proc *p, Ureg *ur)
 {
 	Ureg *cur;
 
-	p->sched.sp = (ulong)p->kstack+KSTACK-UREGSIZE;
+	p->sched.sp = (ulong)p - UREGSIZE;
 	p->sched.pc = (ulong)forkret;
 
 	cur = (Ureg*)(p->sched.sp+2*BY2WD);
diff --git a/sys/src/9/omap/arch.c b/sys/src/9/omap/arch.c
index c0bf9c605..95f875c93 100644
--- a/sys/src/9/omap/arch.c
+++ b/sys/src/9/omap/arch.c
@@ -68,7 +68,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr)entry;
-	p->sched.sp = (uintptr)p->kstack+KSTACK;
+	p->sched.sp = (uintptr)p;
 }
 
 /*
diff --git a/sys/src/9/omap/syscall.c b/sys/src/9/omap/syscall.c
index c89bfa66a..c97ce591c 100644
--- a/sys/src/9/omap/syscall.c
+++ b/sys/src/9/omap/syscall.c
@@ -311,7 +311,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 //print("%lud setting up for forking child %lud\n", up->pid, p->pid);
-	p->sched.sp = (ulong)p->kstack+KSTACK-sizeof(Ureg);
+	p->sched.sp = (ulong)p-sizeof(Ureg);
 	p->sched.pc = (ulong)forkret;
 
 	cureg = (Ureg*)(p->sched.sp);
diff --git a/sys/src/9/omap/trap.c b/sys/src/9/omap/trap.c
index 6c8021f02..72cc504bd 100644
--- a/sys/src/9/omap/trap.c
+++ b/sys/src/9/omap/trap.c
@@ -453,7 +453,7 @@ trap(Ureg *ureg)
 
 	splhi();			/* paranoia */
 	if(up != nil)
-		rem = ((char*)ureg)-up->kstack;
+		rem = ((char*)ureg)-((char*)up-KSTACK);
 	else
 		rem = ((char*)ureg)-((char*)m+sizeof(Mach));
 	if(rem < 1024) {
@@ -663,9 +663,9 @@ dumpstackwithureg(Ureg *ureg)
 	delay(20);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
diff --git a/sys/src/9/pc/mmu.c b/sys/src/9/pc/mmu.c
index be5b9fd25..80701b82d 100644
--- a/sys/src/9/pc/mmu.c
+++ b/sys/src/9/pc/mmu.c
@@ -298,9 +298,9 @@ mmuswitch(Proc* proc)
 		pdb = tmpmap(proc->mmupdb);
 		pdb[PDX(MACHADDR)] = m->pdb[PDX(MACHADDR)];
 		tmpunmap(pdb);
-		taskswitch(proc->mmupdb->pa, (ulong)(proc->kstack+KSTACK));
+		taskswitch(proc->mmupdb->pa, (ulong)proc);
 	}else
-		taskswitch(PADDR(m->pdb), (ulong)(proc->kstack+KSTACK));
+		taskswitch(PADDR(m->pdb), (ulong)proc);
 
 	memmove(&m->gdt[PROCSEG0], proc->gdt, sizeof(proc->gdt));
 	if((x = (ulong)proc->ldt) && (n = proc->nldt) > 0){
diff --git a/sys/src/9/pc/trap.c b/sys/src/9/pc/trap.c
index 584c25309..eb1e8c5fe 100644
--- a/sys/src/9/pc/trap.c
+++ b/sys/src/9/pc/trap.c
@@ -293,9 +293,9 @@ _dumpstack(Ureg *ureg)
 	x += iprint("ktrace /kernel/path %.8lux %.8lux <<EOF\n", ureg->pc, ureg->sp);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
@@ -775,7 +775,7 @@ kprocchild(Proc *p, void (*entry)(void))
 	 * to linkproc().
 	 */
 	p->sched.pc = (ulong)entry;
-	p->sched.sp = (ulong)p->kstack+KSTACK-BY2WD;
+	p->sched.sp = (ulong)p - BY2WD;
 }
 
 void
@@ -788,7 +788,7 @@ forkchild(Proc *p, Ureg *ureg)
 	 *  - the return PC
 	 *  - trap's argument (ur)
 	 */
-	p->sched.sp = (ulong)p->kstack+KSTACK-(sizeof(Ureg)+2*BY2WD);
+	p->sched.sp = (ulong)p - (sizeof(Ureg)+2*BY2WD);
 	p->sched.pc = (ulong)forkret;
 
 	cureg = (Ureg*)(p->sched.sp+2*BY2WD);
diff --git a/sys/src/9/pc64/l.s b/sys/src/9/pc64/l.s
index 76aa2e241..423fad623 100644
--- a/sys/src/9/pc64/l.s
+++ b/sys/src/9/pc64/l.s
@@ -918,10 +918,9 @@ TEXT touser(SB), 1, $-4
 TEXT syscallentry(SB), 1, $-4
 	SWAPGS
 	BYTE $0x65; MOVQ 0, AX			/* m-> (MOVQ GS:0x0, AX) */
-	MOVQ	16(AX), BX			/* m->proc */
+	MOVQ	16(AX), BX
 	MOVQ	SP, R13
-	MOVQ	16(BX), SP			/* m->proc->kstack */
-	ADDQ	$KSTACK, SP
+	MOVQ	BX, SP
 
 	PUSHQ	$UDSEL				/* old stack segment */
 	PUSHQ	R13				/* old sp */
diff --git a/sys/src/9/pc64/mmu.c b/sys/src/9/pc64/mmu.c
index 7f33ccc5a..d2b8b2d04 100644
--- a/sys/src/9/pc64/mmu.c
+++ b/sys/src/9/pc64/mmu.c
@@ -471,7 +471,7 @@ mmuswitch(Proc *proc)
 		m->mmumap[p->index/MAPBITS] |= 1ull<<(p->index%MAPBITS);
 		m->pml4[p->index] = PADDR(p->page) | PTEUSER|PTEWRITE|PTEVALID;
 	}
-	taskswitch((uintptr)proc->kstack+KSTACK);
+	taskswitch((uintptr)proc);
 }
 
 void
diff --git a/sys/src/9/pc64/trap.c b/sys/src/9/pc64/trap.c
index b39c7a082..e18790c33 100644
--- a/sys/src/9/pc64/trap.c
+++ b/sys/src/9/pc64/trap.c
@@ -255,9 +255,9 @@ _dumpstack(Ureg *ureg)
 	x += iprint("ktrace /kernel/path %#p %#p <<EOF\n", ureg->pc, ureg->sp);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
@@ -762,7 +762,7 @@ kprocchild(Proc *p, void (*entry)(void))
 	 * to linkproc().
 	 */
 	p->sched.pc = (uintptr)entry;
-	p->sched.sp = (uintptr)p->kstack+KSTACK-BY2WD;
+	p->sched.sp = (uintptr)p - BY2WD;
 }
 
 void
@@ -775,7 +775,7 @@ forkchild(Proc *p, Ureg *ureg)
 	 *  - the return PC
 	 *  - trap's argument (ur)
 	 */
-	p->sched.sp = (uintptr)p->kstack+KSTACK-(sizeof(Ureg)+2*BY2WD);
+	p->sched.sp = (uintptr)p - (sizeof(Ureg)+2*BY2WD);
 	p->sched.pc = (uintptr)forkret;
 
 	cureg = (Ureg*)(p->sched.sp+2*BY2WD);
diff --git a/sys/src/9/port/portdat.h b/sys/src/9/port/portdat.h
index 8f3904441..5aaad9ada 100644
--- a/sys/src/9/port/portdat.h
+++ b/sys/src/9/port/portdat.h
@@ -653,7 +653,7 @@ struct Schedq
 struct Proc
 {
 	Label	sched;		/* known to l.s */
-	char	*kstack;	/* known to l.s */
+
 	Mach	*mach;		/* machine running this proc */
 	char	*text;
 	char	*user;
diff --git a/sys/src/9/port/proc.c b/sys/src/9/port/proc.c
index 9e0a530d9..1fad45853 100644
--- a/sys/src/9/port/proc.c
+++ b/sys/src/9/port/proc.c
@@ -648,7 +648,6 @@ newproc(void)
 		}
 		p = (Proc*)(b + KSTACK);
 		p->index = procalloc.nextindex++;
-		p->kstack = b;
 		procalloc.tab[p->index] = p;
 	}
 	procalloc.free = p->qnext;
diff --git a/sys/src/9/ppc/l.s b/sys/src/9/ppc/l.s
index 96b166f9e..6fd8f3ab4 100644
--- a/sys/src/9/ppc/l.s
+++ b/sys/src/9/ppc/l.s
@@ -523,9 +523,7 @@ TEXT trapvec(SB), $-4
 	MOVW	$MACHPADDR, R1		/* PADDR(m->) */
 	MOVW	8(R1), R1		/* m->proc */
 	RLWNM	$0, R1, $~KZERO, R1	/* PADDR(m->proc) */
-	MOVW	8(R1), R1		/* m->proc->kstack */
-	RLWNM	$0, R1, $~KZERO, R1	/* PADDR(m->proc->kstack) */
-	ADD	$(KSTACK-UREGSIZE), R1	/* make room on stack */
+	SUB	$UREGSIZE, R1		/* make room on stack */
 
 	BL	saveureg(SB)
 	BL	trap(SB)
diff --git a/sys/src/9/ppc/trap.c b/sys/src/9/ppc/trap.c
index 533f252b4..1aa5862d3 100644
--- a/sys/src/9/ppc/trap.c
+++ b/sys/src/9/ppc/trap.c
@@ -424,8 +424,8 @@ _dumpstack(Ureg *ureg)
 		sl = el-KSTACK;
 	}
 	else{
-		sl = (ulong)up->kstack;
-		el = sl + KSTACK;
+		el = (ulong)up;
+		sl = el-KSTACK;
 	}
 	if(l > el || l < sl){
 		el = (ulong)m+BY2PG;
@@ -462,7 +462,7 @@ dumpregs(Ureg *ur)
 	if(up) {
 		print("registers for %s %ld\n", up->text, up->pid);
 		if((ur->srr1 & MSR_PR) == 0)
-		if(ur->usp < (ulong)up->kstack || ur->usp > (ulong)up->kstack+KSTACK)
+		if(ur->usp < (ulong)up - KSTACK || ur->usp > (ulong)up)
 			print("invalid stack ptr\n");
 	}
 	else
@@ -480,7 +480,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (ulong)entry;
-	p->sched.sp = (ulong)p->kstack+KSTACK;
+	p->sched.sp = (ulong)p;
 }
 
 /*
@@ -517,7 +517,7 @@ forkchild(Proc *p, Ureg *ur)
 {
 	Ureg *cur;
 
-	p->sched.sp = (ulong)p->kstack+KSTACK-UREGSIZE;
+	p->sched.sp = (ulong)p - UREGSIZE;
 	p->sched.pc = (ulong)forkret;
 
 	cur = (Ureg*)(p->sched.sp+2*BY2WD);
diff --git a/sys/src/9/sgi/l.s b/sys/src/9/sgi/l.s
index d3fe25d2b..f52276d6f 100644
--- a/sys/src/9/sgi/l.s
+++ b/sys/src/9/sgi/l.s
@@ -442,8 +442,6 @@ waskernel:
 wasuser:				/* get kernel stack for this user process */
 	GETMACH	(SP)
 	MOVW	8(SP), SP		/*  m->proc */
-	MOVW	8(SP), SP		/*  m->proc->kstack */
-	ADDU	$(KSTACK-UREGSIZE), SP
 
 dosave:
 	MOVW	R31, 0x28(SP)
diff --git a/sys/src/9/sgi/main.c b/sys/src/9/sgi/main.c
index 31d120068..4e0aa75ba 100644
--- a/sys/src/9/sgi/main.c
+++ b/sys/src/9/sgi/main.c
@@ -321,7 +321,7 @@ procsave(Proc *p)
 }
 
 void
-procrestore(Proc *p)
+procrestore(Proc *)
 {
 }
 
diff --git a/sys/src/9/sgi/trap.c b/sys/src/9/sgi/trap.c
index 2bea55c34..c97ee7d08 100644
--- a/sys/src/9/sgi/trap.c
+++ b/sys/src/9/sgi/trap.c
@@ -160,7 +160,7 @@ trap(Ureg *ur)
 	char buf[2*ERRMAX], buf1[ERRMAX], *fpexcep;
 	static int dumps;
 
-	if (up && (char *)(ur) - up->kstack < 1024 && dumps++ == 0) {
+	if (up && (char *)(ur) - ((char *)up - KSTACK) < 1024 && dumps++ == 0) {
 		iprint("trap: proc %ld kernel stack getting full\n", up->pid);
 		dumpregs(ur);
 		dumpstack();
@@ -421,7 +421,7 @@ _dumpstack(Ureg *ureg)
 	if(up == nil)
 		top = (ulong)MACHADDR + MACHSIZE;
 	else
-		top = (ulong)up->kstack + KSTACK;
+		top = (ulong)up;
 	i = 0;
 	for(l=ureg->sp; l < top; l += BY2WD) {
 		v = *(ulong*)l;
@@ -764,7 +764,7 @@ forkchild(Proc *p, Ureg *ur)
 {
 	Ureg *cur;
 
-	p->sched.sp = (ulong)p->kstack+KSTACK-UREGSIZE;
+	p->sched.sp = (ulong)p - UREGSIZE;
 	p->sched.pc = (ulong)forkret;
 
 	cur = (Ureg*)(p->sched.sp+2*BY2WD);
@@ -780,7 +780,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (ulong)entry;
-	p->sched.sp = (ulong)p->kstack+KSTACK;
+	p->sched.sp = (ulong)p;
 }
 
 /* set up user registers before return from exec() */
diff --git a/sys/src/9/teg2/arch.c b/sys/src/9/teg2/arch.c
index d60944a50..565884608 100644
--- a/sys/src/9/teg2/arch.c
+++ b/sys/src/9/teg2/arch.c
@@ -68,7 +68,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr)entry;
-	p->sched.sp = (uintptr)p->kstack+KSTACK;
+	p->sched.sp = (uintptr)p;
 }
 
 /*
diff --git a/sys/src/9/teg2/syscall.c b/sys/src/9/teg2/syscall.c
index d444e7971..6d5c6ba1f 100644
--- a/sys/src/9/teg2/syscall.c
+++ b/sys/src/9/teg2/syscall.c
@@ -342,7 +342,7 @@ forkchild(Proc *p, Ureg *ureg)
 {
 	Ureg *cureg;
 
-	p->sched.sp = (ulong)p->kstack+KSTACK-sizeof(Ureg);
+	p->sched.sp = (ulong)p - sizeof(Ureg);
 	p->sched.pc = (ulong)forkret;
 
 	cureg = (Ureg*)(p->sched.sp);
diff --git a/sys/src/9/teg2/trap.c b/sys/src/9/teg2/trap.c
index 697a5ae3a..af134f8ce 100644
--- a/sys/src/9/teg2/trap.c
+++ b/sys/src/9/teg2/trap.c
@@ -819,7 +819,7 @@ trap(Ureg *ureg)
 
 	splhi();			/* paranoia */
 	if(up != nil)
-		rem = ((char*)ureg)-up->kstack;
+		rem = ((char*)ureg)-((char*)up-KSTACK);
 	else
 		rem = ((char*)ureg)-((char*)m+sizeof(Mach));
 	if(rem < 1024) {
@@ -957,9 +957,9 @@ dumpstackwithureg(Ureg *ureg)
 	delay(20);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
diff --git a/sys/src/9/xen/mmu.c b/sys/src/9/xen/mmu.c
index 250d08371..03017e88d 100644
--- a/sys/src/9/xen/mmu.c
+++ b/sys/src/9/xen/mmu.c
@@ -237,10 +237,10 @@ mmuswitch(Proc* proc)
 		//XXX doesn't work for some reason, but it's not needed for uniprocessor
 		//pdb = (ulong*)proc->mmupdb->va;
 		//xenupdate(&pdb[PDX(MACHADDR)], m->pdb[PDX(MACHADDR)]);
-		taskswitch(proc->mmupdb, (ulong)(proc->kstack+KSTACK));
+		taskswitch(proc->mmupdb, (ulong)proc);
 	}
 	else
-		taskswitch(0, (ulong)(proc->kstack+KSTACK));
+		taskswitch(0, (ulong)proc);
 }
 
 void
diff --git a/sys/src/9/xen/trap.c b/sys/src/9/xen/trap.c
index 72f7e98eb..7527461fc 100644
--- a/sys/src/9/xen/trap.c
+++ b/sys/src/9/xen/trap.c
@@ -263,9 +263,9 @@ _dumpstack(Ureg *ureg)
 	x += print("ktrace /kernel/path %.8lux %.8lux <<EOF\n", ureg->pc, ureg->sp);
 	i = 0;
 	if(up
-	&& (ulong)&l >= (ulong)up->kstack
-	&& (ulong)&l <= (ulong)up->kstack+KSTACK)
-		estack = (ulong)up->kstack+KSTACK;
+	&& (ulong)&l >= (ulong)up - KSTACK
+	&& (ulong)&l <= (ulong)up)
+		estack = (ulong)up;
 	else if((ulong)&l >= (ulong)m->stack
 	&& (ulong)&l <= (ulong)m+BY2PG)
 		estack = (ulong)m+MACHSIZE;
@@ -710,7 +710,7 @@ kprocchild(Proc *p, void (*entry)(void))
 	 * to linkproc().
 	 */
 	p->sched.pc = (ulong)entry;
-	p->sched.sp = (ulong)p->kstack+KSTACK-BY2WD;
+	p->sched.sp = (ulong)p - BY2WD;
 }
 
 void
@@ -723,7 +723,7 @@ forkchild(Proc *p, Ureg *ureg)
 	 *  - the return PC
 	 *  - trap's argument (ur)
 	 */
-	p->sched.sp = (ulong)p->kstack+KSTACK-(sizeof(Ureg)+2*BY2WD);
+	p->sched.sp = (ulong)p - (sizeof(Ureg)+2*BY2WD);
 	p->sched.pc = (ulong)forkret;
 
 	cureg = (Ureg*)(p->sched.sp+2*BY2WD);
diff --git a/sys/src/9/zynq/trap.c b/sys/src/9/zynq/trap.c
index 92bdd4107..c245be526 100644
--- a/sys/src/9/zynq/trap.c
+++ b/sys/src/9/zynq/trap.c
@@ -26,9 +26,9 @@ _dumpstack(Ureg *ureg)
 	x += iprint("ktrace /arm/9zynq %.8lux %.8lux %.8lux <<EOF\n", ureg->pc, ureg->sp, ureg->r14);
 	i = 0;
 	if(up
-	&& (uintptr)&l >= (uintptr)up->kstack
-	&& (uintptr)&l <= (uintptr)up->kstack+KSTACK)
-		estack = (uintptr)up->kstack+KSTACK;
+	&& (uintptr)&l >= (uintptr)up - KSTACK
+	&& (uintptr)&l <= (uintptr)up)
+		estack = (uintptr)up;
 	else if((uintptr)&l >= (uintptr)m->stack
 	&& (uintptr)&l <= (uintptr)m+MACHSIZE)
 		estack = (uintptr)m+MACHSIZE;
@@ -521,7 +521,7 @@ void
 kprocchild(Proc *p, void (*entry)(void))
 {
 	p->sched.pc = (uintptr) entry;
-	p->sched.sp = (uintptr) p->kstack + KSTACK;
+	p->sched.sp = (uintptr) p;
 }
 
 void
@@ -530,7 +530,7 @@ forkchild(Proc *p, Ureg *ureg)
 	Ureg *cureg;
 
 	p->sched.pc = (uintptr) forkret;
-	p->sched.sp = (uintptr) p->kstack + KSTACK - sizeof(Ureg);
+	p->sched.sp = (uintptr) p - sizeof(Ureg);
 
 	cureg = (Ureg*) p->sched.sp;
 	memmove(cureg, ureg, sizeof(Ureg));