From 2f31ea1c82614f1fb2eadae2b21a873d9849a859 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 13 Aug 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-08-13

---
 pc/dat.h       |  1 +
 pc/main.c      | 17 ++++++++---------
 pc/mem.h       |  4 ++++
 pc/trap.c      | 32 +++++++++++++++++++++++++++++++-
 port/chan.c    |  2 +-
 port/devcons.c |  3 +++
 6 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/pc/dat.h b/pc/dat.h
index 0ccf03e826f138c9a438fd3f7165e14386f03ef3..7c18da9cd489f8f750343770fa3c1e57b229bd02 100644
--- a/pc/dat.h
+++ b/pc/dat.h
@@ -195,3 +195,4 @@ extern int	cpuflag;		/* true if this is a CPU */
 extern Mach	*m;
 extern Proc	*up;
 extern char	filaddr[];
+extern ulong	crasharea;
diff --git a/pc/main.c b/pc/main.c
index 711728e7f6576947886c420fce9fd7401b77c8ce..adf43b795de4321f879d011bb605e9e2177c6579 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -31,6 +31,7 @@ char filaddr[NAMELEN];
 char *confname[MAXCONF];
 char *confval[MAXCONF];
 int nconf;
+ulong crasharea;
 
 /* memory map */
 #define MAXMEG 64
@@ -63,6 +64,7 @@ main(void)
 	chandevreset();
 	swapinit();
 	userinit();
+conf.npage0 += CRASHSIZE;
 	schedinit();
 }
 
@@ -353,7 +355,6 @@ confinit(void)
 			/*
 			 *  zero memory to set ECC but skip over the kernel
 			 *  do a quick memory test also
-			 */
 			if(i != 1){
 				for(j = 0; j < MB/BY2PG; j += BY2PG){
 					lp = mapaddr(KZERO|(i*MB+j));
@@ -376,6 +377,7 @@ confinit(void)
 					memset(lp, 0, BY2PG);
 				}
 			}
+			 */
 		}
 		x += 0x3141526;
 	}
@@ -387,16 +389,17 @@ confinit(void)
 	conf.base0 = ktop;
 	for(i = 1; mmap[i] == 'x'; i++)
 		;
-	conf.npage0 = (i*MB - ktop)/BY2PG;
+	conf.npage0 = (i*MB - ktop - CRASHSIZE)/BY2PG;
+	crasharea = KZERO|(conf.base0 + conf.npage0*BY2PG);
 	conf.topofmem = i*MB;
 
 	/*
-	 *  bank1 usually goes from the end of BOOTARGS to 640k
+	 *  bank1 usually goes from the end of BOOTARGS to 640k - crash space
 	 */
-	conf.base1 = (ulong)(BOOTARGS+BOOTARGSLEN);
+	conf.base1 = (ulong)(BOOTARGS + BOOTARGSLEN);
 	conf.base1 = PGROUND(conf.base1);
 	conf.base1 = PADDR(conf.base1);
-	conf.npage1 = (640*1024-conf.base1)/BY2PG;
+	conf.npage1 = (640*1024 - conf.base1)/BY2PG;
 
 	/*
 	 *  if there is a hole in memory (due to a shadow BIOS) make the
@@ -568,15 +571,11 @@ procrestore(Proc *p)
 	USED(p);
 }
 
-
 /*
  *  the following functions all are slightly different from
  *  PC to PC.
  */
 
-/*
- *  reset the i387 chip
- */
 void
 exit(int ispanic)
 {
diff --git a/pc/mem.h b/pc/mem.h
index bceb1403bf2682f341549907b0fde717d42c44e7..4e9680c2bc343390eb60768641c71c4ab2422ad8 100644
--- a/pc/mem.h
+++ b/pc/mem.h
@@ -55,6 +55,10 @@
 
 #define	MACHSIZE	4096
 
+/*
+ *  an area for storing crash info to be picked up later
+ */
+#define CRASHSIZE	(KSTACK+BY2PG)
 
 /*
  *  known 80386 segments (in GDT) and their selectors
diff --git a/pc/trap.c b/pc/trap.c
index 7f4e066d463e615aa3753b2f623919d5df448f6e..14bd520c4df44e25d0e28fb6c45350e6df685a95 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -61,6 +61,19 @@ struct
 	int	free;
 } halloc;
 
+/*
+ *  somewhere to drop crash info
+ */
+typedef struct
+{
+	ulong	magic;
+	void	*kbot;
+	void	*ksp;
+	char	text[NAMELEN];
+	Ureg	ureg;
+	uchar	kstack[KSTACK];
+} Crashstate;
+
 void
 sethvec(int v, void (*r)(void), int type, int pri)
 {
@@ -340,12 +353,20 @@ dumpregs2(Ureg *ur)
 void
 dumpregs(Ureg *ur)
 {
+	Crashstate *cs;
+	extern ulong etext;
 	ulong *x;
 
+
 	x = (ulong*)(ur+1);
 	dumpregs2(ur);
 	print("  magic %lux %lux %lux\n", x[0], x[1], x[2]);
 	print("  ur %lux up %lux\n", ur, up);
+
+	/* save crash info */
+	print("crasharea 0x%lux\n", crasharea);
+	cs = (Crashstate*)crasharea;
+	memmove(&cs->ureg, ur, sizeof(Ureg));
 }
 
 void
@@ -354,13 +375,14 @@ dumpstack(void)
 	ulong l, v, i;
 	extern ulong etext;
 	int lim;
+	Crashstate *cs;
 
 	if(up == 0)
 		return;
 
 	i = 0;
 	lim = 6;
-	for(l=(ulong)&l; l<(ulong)(up->kstack+BY2PG) && lim; l+=4){
+	for(l=(ulong)&l; l<(ulong)(up->kstack+KSTACK) && lim; l+=4){
 		v = *(ulong*)l;
 		if(KTZERO < v && v < (ulong)&etext){
 			print("%lux ", v);
@@ -373,6 +395,14 @@ dumpstack(void)
 		}
 	}
 
+	/* save crash info */
+	print("crasharea 0x%lux\n", crasharea);
+	cs = (Crashstate*)crasharea;
+	memmove(cs->kstack, up->kstack, KSTACK);
+	cs->kbot = up->kstack;
+	memmove(cs->text, up->text, NAMELEN);
+	cs->magic = 0xdeaddead;
+	cs->ksp = &l;
 }
 
 /*
diff --git a/port/chan.c b/port/chan.c
index a0eb28c639a143983ea35918785023c0ac5ee473..419047e7813d2943decbafe057960ecad79eba78 100644
--- a/port/chan.c
+++ b/port/chan.c
@@ -130,7 +130,7 @@ chanfree(Chan *c)
 void
 close(Chan *c)
 {
-	if(c == 0 || (c->flag&CFREE))
+	if(c->flag&CFREE)
 		panic("close");
 
 	if(decref(c))
diff --git a/port/devcons.c b/port/devcons.c
index 070cdf90ca591ea1fdb4c2d9327f82cc273e40b5..fd01cc28c67eba6691d983766ce3f085f1fdbd9e 100644
--- a/port/devcons.c
+++ b/port/devcons.c
@@ -214,6 +214,9 @@ echo(Rune r, char *buf, int n)
 		switch(r){
 		case 0x14:
 			break;	/* pass it on */
+		case 's':
+			dumpstack();
+			break;
 		case 'x':
 			xsummary();
 			ixsummary();