From 972f95aa637ed70a65e0e90d2e589b58a81d8a59 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Tue, 17 Nov 2020 23:30:09 +0100
Subject: pc, pc64: load idt early in trapinit0()

loading the interrupt vector table early allows
us to handle traps during bootup before mmuinit()
which gives better diagnostics for debugging.

we also can handle general protection fault on
rdmsr() and wrmsr() which helps during
cpuidentify() and archinit() when probing for
cpu features.
---
 sys/src/9/pc/main.c   |  4 +---
 sys/src/9/pc/trap.c   | 20 +++++++++-----------
 sys/src/9/pc64/main.c |  2 +-
 sys/src/9/pc64/trap.c | 21 +++++++++------------
 4 files changed, 20 insertions(+), 27 deletions(-)

(limited to 'sys/src')

diff --git a/sys/src/9/pc/main.c b/sys/src/9/pc/main.c
index 231a62ad3..39649d164 100644
--- a/sys/src/9/pc/main.c
+++ b/sys/src/9/pc/main.c
@@ -23,15 +23,13 @@ void
 main(void)
 {
 	mach0init();
+	trapinit0();
 	bootargsinit();
 	ioinit();
 	i8250console();
 	quotefmtinstall();
 	screeninit();
-
 	print("\nPlan 9\n");
-	
-	trapinit0();
 	i8253init();
 	cpuidentify();
 	meminit0();
diff --git a/sys/src/9/pc/trap.c b/sys/src/9/pc/trap.c
index fadb64f42..faaf90101 100644
--- a/sys/src/9/pc/trap.c
+++ b/sys/src/9/pc/trap.c
@@ -9,8 +9,6 @@
 #include	"../port/error.h"
 #include	<trace.h>
 
-static int trapinited;
-
 void	noted(Ureg*, ulong);
 
 static void debugexc(Ureg*, void*);
@@ -197,13 +195,13 @@ trapinit0(void)
 	int d1, v;
 	ulong vaddr;
 	Segdesc *idt;
+	ushort ptr[3];
 
 	idt = (Segdesc*)IDTADDR;
 	vaddr = (ulong)vectortable;
 	for(v = 0; v < 256; v++){
 		d1 = (vaddr & 0xFFFF0000)|SEGP;
 		switch(v){
-
 		case VectorBPT:
 			d1 |= SEGPL(3)|SEGIG;
 			break;
@@ -220,6 +218,10 @@ trapinit0(void)
 		idt[v].d1 = d1;
 		vaddr += 6;
 	}
+	ptr[0] = sizeof(Segdesc)*256-1;
+	ptr[1] = IDTADDR & 0xFFFF;
+	ptr[2] = IDTADDR >> 16;
+	lidt(ptr);
 }
 
 void
@@ -237,7 +239,6 @@ trapinit(void)
 	nmienable();
 
 	addarchfile("irqalloc", 0444, irqallocread, nil);
-	trapinited = 1;
 }
 
 static char* excname[32] = {
@@ -328,13 +329,6 @@ trap(Ureg* ureg)
 	Vctl *ctl, *v;
 	Mach *mach;
 
-	if(!trapinited){
-		/* fault386 can give a better error message */
-		if(ureg->trap == VectorPF)
-			fault386(ureg, nil);
-		panic("trap %lud: not ready", ureg->trap);
-	}
-
 	m->perf.intrts = perfticks();
 	user = userureg(ureg);
 	if(user){
@@ -482,6 +476,10 @@ trap(Ureg* ureg)
 					return;
 				}
 			}
+
+			/* early fault before trapinit() */
+			if(vno == VectorPF)
+				fault386(ureg, 0);
 		}
 
 		dumpregs(ureg);
diff --git a/sys/src/9/pc64/main.c b/sys/src/9/pc64/main.c
index 50649d724..53bcd8887 100644
--- a/sys/src/9/pc64/main.c
+++ b/sys/src/9/pc64/main.c
@@ -175,13 +175,13 @@ void
 main(void)
 {
 	mach0init();
+	trapinit0();
 	bootargsinit();
 	ioinit();
 	i8250console();
 	quotefmtinstall();
 	screeninit();
 	print("\nPlan 9\n");
-	trapinit0();
 	i8253init();
 	cpuidentify();
 	meminit0();
diff --git a/sys/src/9/pc64/trap.c b/sys/src/9/pc64/trap.c
index b1078c560..b7e71a919 100644
--- a/sys/src/9/pc64/trap.c
+++ b/sys/src/9/pc64/trap.c
@@ -9,8 +9,6 @@
 #include	"../port/error.h"
 #include	<trace.h>
 
-static int trapinited;
-
 void	noted(Ureg*, ulong);
 
 static void debugexc(Ureg*, void*);
@@ -194,13 +192,13 @@ trapinit0(void)
 	u32int d1, v;
 	uintptr vaddr;
 	Segdesc *idt;
+	uintptr ptr[2];
 
 	idt = (Segdesc*)IDTADDR;
 	vaddr = (uintptr)vectortable;
 	for(v = 0; v < 256; v++){
 		d1 = (vaddr & 0xFFFF0000)|SEGP;
 		switch(v){
-
 		case VectorBPT:
 			d1 |= SEGPL(3)|SEGIG;
 			break;
@@ -224,6 +222,9 @@ trapinit0(void)
 
 		vaddr += 6;
 	}
+	((ushort*)&ptr[1])[-1] = sizeof(Segdesc)*512-1;
+	ptr[1] = IDTADDR;
+	lidt(&((ushort*)&ptr[1])[-1]);
 }
 
 void
@@ -240,7 +241,6 @@ trapinit(void)
 	trapenable(Vector15, unexpected, 0, "unexpected");
 	nmienable();
 	addarchfile("irqalloc", 0444, irqallocread, nil);
-	trapinited = 1;
 }
 
 static char* excname[32] = {
@@ -324,13 +324,6 @@ trap(Ureg *ureg)
 	Vctl *ctl, *v;
 	Mach *mach;
 
-	if(!trapinited){
-		/* faultamd64 can give a better error message */
-		if(ureg->type == VectorPF)
-			faultamd64(ureg, nil);
-		panic("trap %llud: not ready", ureg->type);
-	}
-
 	m->perf.intrts = perfticks();
 	user = userureg(ureg);
 	if(user){
@@ -447,11 +440,15 @@ trap(Ureg *ureg)
 					return;
 				}
 			} else if(pc == _peekinst){
-				if(vno == VectorGPF){
+				if(vno == VectorGPF || vno == VectorPF){
 					ureg->pc += 2;
 					return;
 				}
 			}
+
+			/* early fault before trapinit() */
+			if(vno == VectorPF)
+				faultamd64(ureg, 0);
 		}
 
 		dumpregs(ureg);
-- 
cgit v1.2.3