From 8a033334d6ecd2a26a0020298eacff755a48678c Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 15 Nov 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-11-15

---
 pc/mmu.c    |  4 ++++
 pc/trap.c   | 26 +++++++++++++-------------
 port/chan.c | 20 ++++++++++++++++----
 port/pgrp.c |  1 -
 4 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/pc/mmu.c b/pc/mmu.c
index 21b62782402bd52c460f98b4f40371b57ec70b5a..80caa5dfc323c3f7ca28695f8f91ebe44a35d13a 100644
--- a/pc/mmu.c
+++ b/pc/mmu.c
@@ -106,6 +106,10 @@ taskswitch(ulong pagetbl, ulong stack)
 {
 	tss.ss0 = KDSEL;
 	tss.sp0 = stack;
+tss.ss1 = KDSEL;
+tss.sp1 = stack;
+tss.ss2 = KDSEL;
+tss.sp2 = stack;
 	tss.cr3 = pagetbl;
 	putcr3(pagetbl);
 }
diff --git a/pc/trap.c b/pc/trap.c
index b614ea310ebf9148d66fa9c155c23ef42143ac27..c7c4ac94ccfd73d050e6470cc432ada4a3985e1e 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -136,9 +136,9 @@ trapinit(void)
 	sethvec(11, intr11, SEGIG, 0);
 	sethvec(12, intr12, SEGIG, 0);
 	sethvec(13, intr13, SEGIG, 0);
-	sethvec(14, intr14, SEGIG, 0);	/* page fault, interrupts off */
+	sethvec(14, intr14, SEGIG, 0);	/* page fault */
 	sethvec(15, intr15, SEGIG, 0);
-	sethvec(16, intr16, SEGIG, 0);	/* math coprocessor, interrupts off */
+	sethvec(16, intr16, SEGIG, 0);	/* math coprocessor */
 
 	/*
 	 *  device interrupts
@@ -223,7 +223,9 @@ Proc *lastup;
 
 
 /*
- *  All traps
+ *  All trapscome here.  It is slower to have all traps call trap() rather than
+ *  directly vectoring the handler.  However, this avoids a lot of code duplication
+ *  and possible bugs.
  */
 void
 trap(Ureg *ur)
@@ -239,13 +241,6 @@ trap(Ureg *ur)
 	if(user)
 		up->dbgreg = ur;
 
-ur->cs &= 0xffff;
-ur->ds &= 0xffff;
-ur->es &= 0xffff;
-ur->fs &= 0xffff;
-ur->gs &= 0xffff;
-if(user) ur->ss &= 0xffff;
-
 	/*
 	 *  tell the 8259 that we're done with the
 	 *  highest level interrupt (interrupts are still
@@ -313,20 +308,25 @@ lastur = ur;
 void
 dumpregs2(Ureg *ur)
 {
+	ur->cs &= 0xffff;
+	ur->ds &= 0xffff;
+	ur->es &= 0xffff;
+	ur->fs &= 0xffff;
+	ur->gs &= 0xffff;
+
 	if(up)
 		print("registers for %s %d\n", up->text, up->pid);
 	else
 		print("registers for kernel\n");
-	print("FLAGS=%lux TRAP=%lux ECODE=%lux CS=%lux PC=%lux", ur->flags, ur->trap,
+	print("FLAGS=%lux TRAP=%lux ECODE=%lux CS=%4.4lux PC=%lux", ur->flags, ur->trap,
 		ur->ecode, ur->cs, ur->pc);
-	print(" SS=%lux USP=%lux\n", ur->ss, ur->usp);
+	print(" SS=%4.4lux USP=%lux\n", ur->ss&0xffff, ur->usp);
 	print("  AX %8.8lux  BX %8.8lux  CX %8.8lux  DX %8.8lux\n",
 		ur->ax, ur->bx, ur->cx, ur->dx);
 	print("  SI %8.8lux  DI %8.8lux  BP %8.8lux\n",
 		ur->si, ur->di, ur->bp);
 	print("  DS %4.4lux  ES %4.4lux  FS %4.4lux  GS %4.4lux\n",
 		ur->ds, ur->es, ur->fs, ur->gs);
-
 }
 
 void
diff --git a/port/chan.c b/port/chan.c
index b90bddd682a721d1cfefacb0dcfd383580d96d60..3ce7e2a2db43a8b29595ffaab53483a72aa6ca89 100644
--- a/port/chan.c
+++ b/port/chan.c
@@ -168,9 +168,9 @@ int
 mount(Chan *new, Chan *old, int flag, char *spec)
 {
 	Pgrp *pg;
-	int order;
-	Mount *nm, *f;
+	int order, flg;
 	Mhead *m, **l;
+	Mount *nm, *f, *um, **h;
 
 	if(CHDIR & (old->qid.path^new->qid.path))
 		error(Emount);
@@ -210,7 +210,17 @@ mount(Chan *new, Chan *old, int flag, char *spec)
 	}
 
 	nm = newmount(m, new, flag, spec);
-
+	if(new->mnt != 0) {
+		h = &nm->next;
+		for(um = new->mnt->next; um; um = um->next) {
+			flg = um->flag;
+			if(flg == 0)
+				flg = MAFTER;
+			f = newmount(m, um->to, flg, um->spec);
+			*h = f;
+			h = &f->next;
+		}
+	}
 
 	if(flag & MCREATE)
 		new->flag |= CCREATE;
@@ -221,7 +231,9 @@ mount(Chan *new, Chan *old, int flag, char *spec)
 		f->next = nm;
 	}
 	else {
-		nm->next = m->mount;
+		for(f = nm; f->next; f = f->next)
+			;
+		f->next = m->mount;
 		m->mount = nm;
 	}
 
diff --git a/port/pgrp.c b/port/pgrp.c
index 6cef5618fa0f5f85de77c37b7a2f79b5c40e1bbc..a4a518507550b72880e6aabe033613880927b9c1 100644
--- a/port/pgrp.c
+++ b/port/pgrp.c
@@ -140,7 +140,6 @@ closefgrp(Fgrp *f)
 	}
 }
 
-
 Mount*
 newmount(Mhead *mh, Chan *to, int flag, char *spec)
 {