From ed5c9fd00a2e34a8a45288c986d52ac499db393b Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Thu, 25 Dec 2014 11:30:29 +0100
Subject: [PATCH] zynq: only tmpmap() while splhi(), remove unneeded
 coherence() after tmpunmap(), splhi() in l2free()

we have to call tmpmap() with interrupts disabled as the map
is a per cpu and a interrupt can preempt us while we where
commited to use a entry but *before* we wrote it!

tmpunmap() already calls coherence() before flushpg() so it
is not needed after tmpunmap().

splhi() in l2free() isnt needed as l2free() is always called
with interrupts disabled from mmuswitch() and mmurelease().
---
 sys/src/9/zynq/mmu.c | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/sys/src/9/zynq/mmu.c b/sys/src/9/zynq/mmu.c
index f2fa6e0f9..d5561fcd0 100644
--- a/sys/src/9/zynq/mmu.c
+++ b/sys/src/9/zynq/mmu.c
@@ -100,13 +100,11 @@ upallocl1(void)
 static void
 l2free(Proc *proc)
 {
-	int s;
 	ulong *t;
 	Page *p, **l;
 
 	if(proc->l1 == nil || proc->mmuused == nil)
 		return;
-	s = splhi();
 	l = &proc->mmuused;
 	for(p = *l; p != nil; p = p->next){
 		t = proc->l1->va + p->daddr;
@@ -116,7 +114,6 @@ l2free(Proc *proc)
 		*t = 0;
 		l = &p->next;
 	}
-	splx(s);
 	*l = proc->mmufree;
 	proc->mmufree = proc->mmuused;
 	proc->mmuused = 0;
@@ -143,6 +140,7 @@ putmmu(uintptr va, uintptr pa, Page *pg)
 	ulong *l2;
 	PTE old;
 	uintptr l2p;
+	int s;
 
 	if(up->l1 == nil)
 		upallocl1();
@@ -150,11 +148,15 @@ putmmu(uintptr va, uintptr pa, Page *pg)
 		pa |= L2CACHED;
 	e = &up->l1->va[L1RX(va)];
 	if((*e & 3) == 0){
-		if(up->mmufree != nil){
-			p = up->mmufree;
+		p = up->mmufree;
+		if(p != nil)
 			up->mmufree = p->next;
-		}else
+		else
 			p = newpage(0, 0, 0);
+		p->daddr = L1RX(va);
+		p->next = up->mmuused;
+		up->mmuused = p;
+		s = splhi();
 		l2p = p->pa;
 		l2 = tmpmap(l2p);
 		memset(l2, 0, BY2PG);
@@ -164,10 +166,8 @@ putmmu(uintptr va, uintptr pa, Page *pg)
 		e[2] = e[1] + L2SZ;
 		e[3] = e[2] + L2SZ;
 		coherence();
-		p->daddr = L1RX(va);
-		p->next = up->mmuused;
-		up->mmuused = p;
 	}else{
+		s = splhi();
 		l2p = *e & ~(BY2PG - 1);
 		l2 = tmpmap(l2p);
 	}
@@ -175,7 +175,7 @@ putmmu(uintptr va, uintptr pa, Page *pg)
 	old = *e;
 	*e = pa | L2VALID | L2USER | L2LOCAL;
 	tmpunmap(l2);
-	coherence();
+	splx(s);
 	if((old & L2VALID) != 0)
 		flushpg((void *) va);
 	if(pg->cachectl[0] == PG_TXTFLUSH){
@@ -274,8 +274,7 @@ KMap *
 kmap(Page *page)
 {
 	ulong *e, *v;
-	int i;
-	ulong s;
+	int i, s;
 
 	if(up == nil)
 		panic("kmap: up=0 pc=%#.8lux", getcallerpc(&page));
@@ -283,23 +282,20 @@ kmap(Page *page)
 		upallocl1();
 	if(up->nkmap < 0)
 		panic("kmap %lud %s: nkmap=%d", up->pid, up->text, up->nkmap);
-	s = splhi();
 	up->nkmap++;
 	e = &up->l1->va[L1X(KMAP)];
 	if((*e & 3) == 0){
 		if(up->kmaptable != nil)
 			panic("kmaptable");
-		spllo();
 		up->kmaptable = newpage(0, 0, 0);
-		splhi();
+		s = splhi();
 		v = tmpmap(up->kmaptable->pa);
 		memset(v, 0, BY2PG);
 		v[0] = page->pa | L2KERRW | L2VALID | L2CACHED | L2LOCAL;
 		v[NKMAP] = up->kmaptable->pa | L2KERRW | L2VALID | L2CACHED | L2LOCAL;
 		tmpunmap(v);
-		coherence();
-		*e = up->kmaptable->pa | L1PT;
 		splx(s);
+		*e = up->kmaptable->pa | L1PT;
 		coherence();
 		return (KMap *) KMAP;
 	}
@@ -309,7 +305,6 @@ kmap(Page *page)
 	for(i = 0; i < NKMAP; i++)
 		if((e[i] & 3) == 0){
 			e[i] = page->pa | L2KERRW | L2VALID | L2CACHED | L2LOCAL;
-			splx(s);
 			coherence();
 			return (KMap *) (KMAP + i * BY2PG);
 		}
@@ -345,6 +340,8 @@ tmpmap(ulong pa)
 	ulong *u, *ub, *ue;
 	void *v;
 
+	if(islo())
+		panic("tmpmap: islow %#p", getcallerpc(&pa));
 	if(cankaddr(pa))
 		return KADDR(pa);
 	ub = (ulong *) TMAPL2(m->machno);