i386/exception.s,

	Keep track of interrupt nesting level.  It is normally 0
	for syscalls and traps, but is fudged to 1 for their exit
	processing in case they metamorphose into an interrupt
	handler.

i386/genassym.c;
	Remove support for the obsolete pcb_iml and pcb_cmap2.

	Add support for pcb_inl.

i386/swtch.s:
	Fudge the interrupt nesting level across context switches and in
	the idle loop so that the work for preemptive context switches
	gets counted as interrupt time, the work for voluntary context
	switches gets counted mostly as system time (the part when
	curproc == 0 gets counted as interrupt time), and only truly idle
	time gets counted as idle time.

	Remove obsolete support (commented out and otherwise) for pcb_iml.

	Load curpcb just before curproc instead of just after so that
	curpcb is always valid if curproc is.  A few more changes like
	this may fix tracing through context switches.

	Remove obsolete function swtch_to_inactive().

include/cpu.h:
	Use the new interrupt nesting level variable to implement a
	non-fake CLF_INTR() so that accounting for the interrupt state
	works.

	You can use top, iostat or (best) an up to date systat to see
	interrupt overheads.  I see the expected huge interrupt overheads
	for ISA devices (on a 486DX/33, about 55% for an IDE drive
	transferring 1250K/sec and the same for a WD8013EBT network card
	transferring 1100K/sec).  The huge interrupt overheads for serial
	devices are unfortunately normally invisible.

include/pcb.h:
	Remove the obsolete pcb_iml and pcb_cmap2.  Replace them by
	padding to preserve binary compatibility.

	Use part of the new padding for pcb_inl.

isa/icu.s:
isa/vector.s:
	Keep track of interrupt nesting level.

16 files changed, 122 insertions, 172 deletions

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 571d9c9dbc8b..62a970296c26 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.16 1994/10/25 07:25:56 davidg Exp $
+ *	$Id: swtch.s,v 1.17 1994/10/30 20:09:13 bde Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -250,13 +250,19 @@ _idle:
 	ALIGN_TEXT
 idle_loop:
 	cli
+	movb	$1,_intr_nesting_level		/* charge Intr if we leave */
 	cmpl	$0,_whichrtqs			/* real-time queue */
 	jne	sw1a
 	cmpl	$0,_whichqs			/* normal queue */
 	jne	nortqr
 	cmpl	$0,_whichidqs			/* 'idle' queue */
 	jne	idqr
+	movb	$0,_intr_nesting_level		/* charge Idle for this loop */
 #ifdef APM
+	/*
+	 * XXX it breaks the rules to call a function while interrupts are
+	 * disabled.  How long before apm enables them?
+	 */
 	call	_apm_cpu_idle
 	call	_apm_cpu_busy
 #else
@@ -294,24 +300,24 @@ ENTRY(cpu_switch)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
 
+	movb	_intr_nesting_level,%al
+	movb	%al,PCB_INL(%ecx)
+
 #if NNPX > 0
 	/* have we used fp, and need a save? */
 	mov	_curproc,%eax
 	cmp	%eax,_npxproc
 	jne	1f
-	pushl	%ecx				/* h/w bugs make saving complicated */
-	leal	PCB_SAVEFPU(%ecx),%eax
-	pushl	%eax
+	addl	$PCB_SAVEFPU,%ecx		/* h/w bugs make saving complicated */
+	pushl	%ecx
 	call	_npxsave			/* do it in a big C function */
 	popl	%eax
-	popl	%ecx
 1:
 #endif	/* NNPX > 0 */
 
-	movl	$0,_curproc			/*  out of process */
+	movb	$1,_intr_nesting_level		/* charge Intr, not Sys/Idle */
 
-#	movw	_cpl,%ax
-#	movw	%ax,PCB_IML(%ecx)		/* save ipl */
+	movl	$0,_curproc			/* out of process */
 
 	/* save is done, now choose a new process or idle */
 sw1:
@@ -436,8 +442,11 @@ swtch_com:
 	movl	PCB_EIP(%edx),%eax
 	movl	%eax,(%esp)
 
-	movl	%ecx,_curproc			/* into next process */
 	movl	%edx,_curpcb
+	movl	%ecx,_curproc			/* into next process */
+
+	movb	PCB_INL(%edx),%al
+	movb	%al,_intr_nesting_level
 
 #ifdef	USER_LDT
 	cmpl	$0, PCB_USERLDT(%edx)
@@ -454,46 +463,12 @@ swtch_com:
 2:
 #endif
 
-	pushl	%edx				/* save p to return */
-/*
- * XXX - 0.0 forgot to save it - is that why this was commented out in 0.1?
- * I think restoring the cpl is unnecessary, but we must turn off the cli
- * now that spl*() don't do it as a side affect.
- */
-	pushl	PCB_IML(%edx)
 	sti
-#if 0
-	call	_splx
-#endif
-	addl	$4,%esp
-/*
- * XXX - 0.0 gets here via swtch_to_inactive().  I think 0.1 gets here in the
- * same way.  Better return a value.
- */
-	popl	%eax				/* return(p); */
 	ret
 
 ENTRY(mvesp)
 	movl	%esp,%eax
 	ret
-/*
- * struct proc *swtch_to_inactive(struct proc *p);
- *
- * At exit of a process, move off the address space of the
- * process and onto a "safe" one. Then, on a temporary stack
- * return and run code that disposes of the old state.
- * Since this code requires a parameter from the "old" stack,
- * pass it back as a return value.
- */
-ENTRY(swtch_to_inactive)
-	popl	%edx				/* old pc */
-	popl	%eax				/* arg, our return value */
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3			/* good bye address space */
- #write buffer?
-	movl	$tmpstk,%esp			/* temporary stack, compensated for call */
-	MEXITCOUNT
-	jmp	%edx				/* return, execute remainder of cleanup */
 
 /*
  * savectx(pcb, altreturn)
@@ -502,8 +477,6 @@ ENTRY(swtch_to_inactive)
  */
 ENTRY(savectx)
 	movl	4(%esp),%ecx
-	movw	_cpl,%ax
-	movw	%ax,PCB_IML(%ecx)
 	movl	(%esp),%eax
 	movl	%eax,PCB_EIP(%ecx)
 	movl	%ebx,PCB_EBX(%ecx)
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S
index d746f12d5fad..e14934b3d7f7 100644
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: exception.s,v 1.4 1994/08/13 03:49:38 wollman Exp $
+ *	$Id: exception.s,v 1.5 1994/09/28 03:37:49 bde Exp $
  */
 
 #include "npx.h"				/* NNPX */
@@ -130,9 +130,11 @@ IDTVEC(rsvd)
 IDTVEC(fpu)
 #if NNPX > 0
 	/*
-	 * Handle like an interrupt so that we can call npxintr to clear the
-	 * error.  It would be better to handle npx interrupts as traps but
-	 * this is difficult for nested interrupts.
+	 * Handle like an interrupt (except for accounting) so that we can
+	 * call npxintr to clear the error.  It would be better to handle
+	 * npx interrupts as traps.  This used to be difficult for nested
+	 * interrupts, but now it is fairly easy - mask nested ones the
+	 * same as SWI_AST's.
 	 */
 	pushl	$0				/* dumby error code */
 	pushl	$0				/* dumby trap type */
@@ -150,6 +152,7 @@ IDTVEC(fpu)
 	orl	$SWI_AST_MASK,%eax
 	movl	%eax,_cpl
 	call	_npxintr
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 #else	/* NNPX > 0 */
@@ -217,6 +220,7 @@ calltrap:
 	 */
 	pushl	%eax
 	subl	$4,%esp
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
@@ -265,6 +269,7 @@ IDTVEC(syscall)
 	 */
 	pushl	$0				/* cpl to restore */
 	subl	$4,%esp
+	movb	$1,_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
diff --git a/sys/amd64/amd64/exception.s b/sys/amd64/amd64/exception.s
index d746f12d5fad..e14934b3d7f7 100644
--- a/sys/amd64/amd64/exception.s
+++ b/sys/amd64/amd64/exception.s
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: exception.s,v 1.4 1994/08/13 03:49:38 wollman Exp $
+ *	$Id: exception.s,v 1.5 1994/09/28 03:37:49 bde Exp $
  */
 
 #include "npx.h"				/* NNPX */
@@ -130,9 +130,11 @@ IDTVEC(rsvd)
 IDTVEC(fpu)
 #if NNPX > 0
 	/*
-	 * Handle like an interrupt so that we can call npxintr to clear the
-	 * error.  It would be better to handle npx interrupts as traps but
-	 * this is difficult for nested interrupts.
+	 * Handle like an interrupt (except for accounting) so that we can
+	 * call npxintr to clear the error.  It would be better to handle
+	 * npx interrupts as traps.  This used to be difficult for nested
+	 * interrupts, but now it is fairly easy - mask nested ones the
+	 * same as SWI_AST's.
 	 */
 	pushl	$0				/* dumby error code */
 	pushl	$0				/* dumby trap type */
@@ -150,6 +152,7 @@ IDTVEC(fpu)
 	orl	$SWI_AST_MASK,%eax
 	movl	%eax,_cpl
 	call	_npxintr
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 #else	/* NNPX > 0 */
@@ -217,6 +220,7 @@ calltrap:
 	 */
 	pushl	%eax
 	subl	$4,%esp
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
@@ -265,6 +269,7 @@ IDTVEC(syscall)
 	 */
 	pushl	$0				/* cpl to restore */
 	subl	$4,%esp
+	movb	$1,_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c
index d3cd26d665a8..585c3198d2fc 100644
--- a/sys/amd64/amd64/genassym.c
+++ b/sys/amd64/amd64/genassym.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)genassym.c	5.11 (Berkeley) 5/10/91
- *	$Id: genassym.c,v 1.19 1994/10/26 22:01:11 bde Exp $
+ *	$Id: genassym.c,v 1.20 1994/11/18 05:27:32 phk Exp $
  */
 
 #include <stdio.h>
@@ -164,8 +164,7 @@ main()
 	printf("#define\tPCB_SAVEFPU %d\n", &pcb->pcb_savefpu);
 	printf("#define\tFP_USESEMC %d\n", FP_USESEMC);
 	printf("#define\tPCB_SAVEEMC %d\n", &pcb->pcb_saveemc);
-	printf("#define\tPCB_CMAP2 %d\n", &pcb->pcb_cmap2);
-	printf("#define\tPCB_IML %d\n", &pcb->pcb_iml);
+	printf("#define\tPCB_INL %d\n", &pcb->pcb_inl);
 	printf("#define\tPCB_ONFAULT %d\n", &pcb->pcb_onfault);
 
 	printf("#define\tTF_ES %d\n", &tf->tf_es);
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index 571d9c9dbc8b..62a970296c26 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.16 1994/10/25 07:25:56 davidg Exp $
+ *	$Id: swtch.s,v 1.17 1994/10/30 20:09:13 bde Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -250,13 +250,19 @@ _idle:
 	ALIGN_TEXT
 idle_loop:
 	cli
+	movb	$1,_intr_nesting_level		/* charge Intr if we leave */
 	cmpl	$0,_whichrtqs			/* real-time queue */
 	jne	sw1a
 	cmpl	$0,_whichqs			/* normal queue */
 	jne	nortqr
 	cmpl	$0,_whichidqs			/* 'idle' queue */
 	jne	idqr
+	movb	$0,_intr_nesting_level		/* charge Idle for this loop */
 #ifdef APM
+	/*
+	 * XXX it breaks the rules to call a function while interrupts are
+	 * disabled.  How long before apm enables them?
+	 */
 	call	_apm_cpu_idle
 	call	_apm_cpu_busy
 #else
@@ -294,24 +300,24 @@ ENTRY(cpu_switch)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
 
+	movb	_intr_nesting_level,%al
+	movb	%al,PCB_INL(%ecx)
+
 #if NNPX > 0
 	/* have we used fp, and need a save? */
 	mov	_curproc,%eax
 	cmp	%eax,_npxproc
 	jne	1f
-	pushl	%ecx				/* h/w bugs make saving complicated */
-	leal	PCB_SAVEFPU(%ecx),%eax
-	pushl	%eax
+	addl	$PCB_SAVEFPU,%ecx		/* h/w bugs make saving complicated */
+	pushl	%ecx
 	call	_npxsave			/* do it in a big C function */
 	popl	%eax
-	popl	%ecx
 1:
 #endif	/* NNPX > 0 */
 
-	movl	$0,_curproc			/*  out of process */
+	movb	$1,_intr_nesting_level		/* charge Intr, not Sys/Idle */
 
-#	movw	_cpl,%ax
-#	movw	%ax,PCB_IML(%ecx)		/* save ipl */
+	movl	$0,_curproc			/* out of process */
 
 	/* save is done, now choose a new process or idle */
 sw1:
@@ -436,8 +442,11 @@ swtch_com:
 	movl	PCB_EIP(%edx),%eax
 	movl	%eax,(%esp)
 
-	movl	%ecx,_curproc			/* into next process */
 	movl	%edx,_curpcb
+	movl	%ecx,_curproc			/* into next process */
+
+	movb	PCB_INL(%edx),%al
+	movb	%al,_intr_nesting_level
 
 #ifdef	USER_LDT
 	cmpl	$0, PCB_USERLDT(%edx)
@@ -454,46 +463,12 @@ swtch_com:
 2:
 #endif
 
-	pushl	%edx				/* save p to return */
-/*
- * XXX - 0.0 forgot to save it - is that why this was commented out in 0.1?
- * I think restoring the cpl is unnecessary, but we must turn off the cli
- * now that spl*() don't do it as a side affect.
- */
-	pushl	PCB_IML(%edx)
 	sti
-#if 0
-	call	_splx
-#endif
-	addl	$4,%esp
-/*
- * XXX - 0.0 gets here via swtch_to_inactive().  I think 0.1 gets here in the
- * same way.  Better return a value.
- */
-	popl	%eax				/* return(p); */
 	ret
 
 ENTRY(mvesp)
 	movl	%esp,%eax
 	ret
-/*
- * struct proc *swtch_to_inactive(struct proc *p);
- *
- * At exit of a process, move off the address space of the
- * process and onto a "safe" one. Then, on a temporary stack
- * return and run code that disposes of the old state.
- * Since this code requires a parameter from the "old" stack,
- * pass it back as a return value.
- */
-ENTRY(swtch_to_inactive)
-	popl	%edx				/* old pc */
-	popl	%eax				/* arg, our return value */
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3			/* good bye address space */
- #write buffer?
-	movl	$tmpstk,%esp			/* temporary stack, compensated for call */
-	MEXITCOUNT
-	jmp	%edx				/* return, execute remainder of cleanup */
 
 /*
  * savectx(pcb, altreturn)
@@ -502,8 +477,6 @@ ENTRY(swtch_to_inactive)
  */
 ENTRY(savectx)
 	movl	4(%esp),%ecx
-	movw	_cpl,%ax
-	movw	%ax,PCB_IML(%ecx)
 	movl	(%esp),%eax
 	movl	%eax,PCB_EIP(%ecx)
 	movl	%ebx,PCB_EBX(%ecx)
diff --git a/sys/amd64/include/cpu.h b/sys/amd64/include/cpu.h
index 79c80af109d2..5d4ce70bc11f 100644
--- a/sys/amd64/include/cpu.h
+++ b/sys/amd64/include/cpu.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)cpu.h	5.4 (Berkeley) 5/9/91
- *	$Id: cpu.h,v 1.16 1994/11/05 22:44:34 bde Exp $
+ *	$Id: cpu.h,v 1.17 1994/11/26 09:27:58 phk Exp $
  */
 
 #ifndef _MACHINE_CPU_H_
@@ -58,8 +58,8 @@
 #define cpu_set_init_frame(p, fp)	(p)->p_md.md_regs = fp
 
 #define	CLKF_USERMODE(framep)	(ISPL((framep)->cf_cs) == SEL_UPL)
-#define CLKF_INTR(framep)	(0)
-#if 0
+#define CLKF_INTR(framep)	(intr_nesting_level >= 2)
+#if 1
 /*
  * XXX splsoftclock() is very broken and barely worth fixing.  It doesn't
  * turn off the clock bit in imen or in the icu.  (This is not a serious
@@ -127,6 +127,7 @@ struct cpu_nameclass {
 extern int	bootverbose;
 extern int	cpu;
 extern int	cpu_class;
+extern u_char	intr_nesting_level;
 extern struct cpu_nameclass i386_cpus[];
 extern int	want_resched;	/* resched was called */
 
diff --git a/sys/amd64/include/pcb.h b/sys/amd64/include/pcb.h
index 37b76f85832d..8ce7febb5ada 100644
--- a/sys/amd64/include/pcb.h
+++ b/sys/amd64/include/pcb.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)pcb.h	5.10 (Berkeley) 5/12/91
- *	$Id: pcb.h,v 1.6 1994/08/13 03:49:50 wollman Exp $
+ *	$Id: pcb.h,v 1.7 1994/10/08 22:21:33 phk Exp $
  */
 
 #ifndef _I386_PCB_H_
@@ -73,10 +73,10 @@ struct pcb {
 #endif
 #define	FP_USESEMC	0x08	/* process uses EMC memory-mapped mode */
 #define	FP_SOFTFP	0x20	/* process using software fltng pnt emulator */
-	short	pcb_iml;	/* interrupt mask level */
+	u_char	pcb_inl;	/* intr_nesting_level at context switch */
 	caddr_t	pcb_onfault;	/* copyin/out fault recovery */
 	long	pcb_sigc[8];	/* XXX signal code trampoline */
-	int	pcb_cmap2;	/* XXX temporary PTE - will prefault instead */
+	int	pad2;		/* XXX unused - remove it if you change struct */
 };
 
 /*
diff --git a/sys/amd64/isa/vector.S b/sys/amd64/isa/vector.S
index 1bc2324f62d9..fcd0a7711d2a 100644
--- a/sys/amd64/isa/vector.S
+++ b/sys/amd64/isa/vector.S
@@ -1,6 +1,6 @@
 /*
  *	from: vector.s, 386BSD 0.1 unknown origin
- *	$Id: vector.s,v 1.9 1994/09/20 21:35:49 bde Exp $
+ *	$Id: vector.s,v 1.10 1994/11/01 23:29:50 bde Exp $
  */
 
 #include <i386/isa/icu.h>
@@ -147,6 +147,7 @@ IDTVEC(fastintr/**/irq_num) ; \
 	movl	(2+8+1)*4(%esp),%eax ;	/* ... cpl from thin frame */ \
 	pushl	%eax ; \
 	subl	$4,%esp ;	/* junk for unit number */ \
+	incb	_intr_nesting_level ; \
 	MEXITCOUNT ; \
 	jmp	_doreti
 
@@ -172,7 +173,7 @@ IDTVEC(intr/**/irq_num) ; \
 	movl	_cpl,%eax ; \
 	testb	$IRQ_BIT(irq_num),%reg ; \
 	jne	2f ; \
-1: ; \
+	incb	_intr_nesting_level ; \
 Xresume/**/irq_num: ; \
 	FAKE_MCOUNT(12*4(%esp)) ;	/* XXX late to avoid double count */ \
 	movl	_intr_countp + (irq_num) * 4,%eax ; \
@@ -254,6 +255,10 @@ imasks:				/* masks for interrupt handlers */
 	.space	NHWI*4		/* padding; HWI masks are elsewhere */
 	.long	SWI_TTY_MASK, SWI_NET_MASK, 0, 0, 0, 0, 0, 0
 	.long	0, 0, 0, 0, 0, 0, SWI_CLOCK_MASK, SWI_AST_MASK
+	.globl	_intr_nesting_level
+_intr_nesting_level:
+	.byte	0
+	.space	3
 
 /*
  * Interrupt counters and names.  The format of these and the label names
diff --git a/sys/amd64/isa/vector.s b/sys/amd64/isa/vector.s
index 1bc2324f62d9..fcd0a7711d2a 100644
--- a/sys/amd64/isa/vector.s
+++ b/sys/amd64/isa/vector.s
@@ -1,6 +1,6 @@
 /*
  *	from: vector.s, 386BSD 0.1 unknown origin
- *	$Id: vector.s,v 1.9 1994/09/20 21:35:49 bde Exp $
+ *	$Id: vector.s,v 1.10 1994/11/01 23:29:50 bde Exp $
  */
 
 #include <i386/isa/icu.h>
@@ -147,6 +147,7 @@ IDTVEC(fastintr/**/irq_num) ; \
 	movl	(2+8+1)*4(%esp),%eax ;	/* ... cpl from thin frame */ \
 	pushl	%eax ; \
 	subl	$4,%esp ;	/* junk for unit number */ \
+	incb	_intr_nesting_level ; \
 	MEXITCOUNT ; \
 	jmp	_doreti
 
@@ -172,7 +173,7 @@ IDTVEC(intr/**/irq_num) ; \
 	movl	_cpl,%eax ; \
 	testb	$IRQ_BIT(irq_num),%reg ; \
 	jne	2f ; \
-1: ; \
+	incb	_intr_nesting_level ; \
 Xresume/**/irq_num: ; \
 	FAKE_MCOUNT(12*4(%esp)) ;	/* XXX late to avoid double count */ \
 	movl	_intr_countp + (irq_num) * 4,%eax ; \
@@ -254,6 +255,10 @@ imasks:				/* masks for interrupt handlers */
 	.space	NHWI*4		/* padding; HWI masks are elsewhere */
 	.long	SWI_TTY_MASK, SWI_NET_MASK, 0, 0, 0, 0, 0, 0
 	.long	0, 0, 0, 0, 0, 0, SWI_CLOCK_MASK, SWI_AST_MASK
+	.globl	_intr_nesting_level
+_intr_nesting_level:
+	.byte	0
+	.space	3
 
 /*
  * Interrupt counters and names.  The format of these and the label names
diff --git a/sys/i386/i386/exception.s b/sys/i386/i386/exception.s
index d746f12d5fad..e14934b3d7f7 100644
--- a/sys/i386/i386/exception.s
+++ b/sys/i386/i386/exception.s
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: exception.s,v 1.4 1994/08/13 03:49:38 wollman Exp $
+ *	$Id: exception.s,v 1.5 1994/09/28 03:37:49 bde Exp $
  */
 
 #include "npx.h"				/* NNPX */
@@ -130,9 +130,11 @@ IDTVEC(rsvd)
 IDTVEC(fpu)
 #if NNPX > 0
 	/*
-	 * Handle like an interrupt so that we can call npxintr to clear the
-	 * error.  It would be better to handle npx interrupts as traps but
-	 * this is difficult for nested interrupts.
+	 * Handle like an interrupt (except for accounting) so that we can
+	 * call npxintr to clear the error.  It would be better to handle
+	 * npx interrupts as traps.  This used to be difficult for nested
+	 * interrupts, but now it is fairly easy - mask nested ones the
+	 * same as SWI_AST's.
 	 */
 	pushl	$0				/* dumby error code */
 	pushl	$0				/* dumby trap type */
@@ -150,6 +152,7 @@ IDTVEC(fpu)
 	orl	$SWI_AST_MASK,%eax
 	movl	%eax,_cpl
 	call	_npxintr
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 #else	/* NNPX > 0 */
@@ -217,6 +220,7 @@ calltrap:
 	 */
 	pushl	%eax
 	subl	$4,%esp
+	incb	_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
@@ -265,6 +269,7 @@ IDTVEC(syscall)
 	 */
 	pushl	$0				/* cpl to restore */
 	subl	$4,%esp
+	movb	$1,_intr_nesting_level
 	MEXITCOUNT
 	jmp	_doreti
 
diff --git a/sys/i386/i386/genassym.c b/sys/i386/i386/genassym.c
index d3cd26d665a8..585c3198d2fc 100644
--- a/sys/i386/i386/genassym.c
+++ b/sys/i386/i386/genassym.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)genassym.c	5.11 (Berkeley) 5/10/91
- *	$Id: genassym.c,v 1.19 1994/10/26 22:01:11 bde Exp $
+ *	$Id: genassym.c,v 1.20 1994/11/18 05:27:32 phk Exp $
  */
 
 #include <stdio.h>
@@ -164,8 +164,7 @@ main()
 	printf("#define\tPCB_SAVEFPU %d\n", &pcb->pcb_savefpu);
 	printf("#define\tFP_USESEMC %d\n", FP_USESEMC);
 	printf("#define\tPCB_SAVEEMC %d\n", &pcb->pcb_saveemc);
-	printf("#define\tPCB_CMAP2 %d\n", &pcb->pcb_cmap2);
-	printf("#define\tPCB_IML %d\n", &pcb->pcb_iml);
+	printf("#define\tPCB_INL %d\n", &pcb->pcb_inl);
 	printf("#define\tPCB_ONFAULT %d\n", &pcb->pcb_onfault);
 
 	printf("#define\tTF_ES %d\n", &tf->tf_es);
diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s
index 571d9c9dbc8b..62a970296c26 100644
--- a/sys/i386/i386/swtch.s
+++ b/sys/i386/i386/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.16 1994/10/25 07:25:56 davidg Exp $
+ *	$Id: swtch.s,v 1.17 1994/10/30 20:09:13 bde Exp $
  */
 
 #include "npx.h"	/* for NNPX */
@@ -250,13 +250,19 @@ _idle:
 	ALIGN_TEXT
 idle_loop:
 	cli
+	movb	$1,_intr_nesting_level		/* charge Intr if we leave */
 	cmpl	$0,_whichrtqs			/* real-time queue */
 	jne	sw1a
 	cmpl	$0,_whichqs			/* normal queue */
 	jne	nortqr
 	cmpl	$0,_whichidqs			/* 'idle' queue */
 	jne	idqr
+	movb	$0,_intr_nesting_level		/* charge Idle for this loop */
 #ifdef APM
+	/*
+	 * XXX it breaks the rules to call a function while interrupts are
+	 * disabled.  How long before apm enables them?
+	 */
 	call	_apm_cpu_idle
 	call	_apm_cpu_busy
 #else
@@ -294,24 +300,24 @@ ENTRY(cpu_switch)
 	movl	%esi,PCB_ESI(%ecx)
 	movl	%edi,PCB_EDI(%ecx)
 
+	movb	_intr_nesting_level,%al
+	movb	%al,PCB_INL(%ecx)
+
 #if NNPX > 0
 	/* have we used fp, and need a save? */
 	mov	_curproc,%eax
 	cmp	%eax,_npxproc
 	jne	1f
-	pushl	%ecx				/* h/w bugs make saving complicated */
-	leal	PCB_SAVEFPU(%ecx),%eax
-	pushl	%eax
+	addl	$PCB_SAVEFPU,%ecx		/* h/w bugs make saving complicated */
+	pushl	%ecx
 	call	_npxsave			/* do it in a big C function */
 	popl	%eax
-	popl	%ecx
 1:
 #endif	/* NNPX > 0 */
 
-	movl	$0,_curproc			/*  out of process */
+	movb	$1,_intr_nesting_level		/* charge Intr, not Sys/Idle */
 
-#	movw	_cpl,%ax
-#	movw	%ax,PCB_IML(%ecx)		/* save ipl */
+	movl	$0,_curproc			/* out of process */
 
 	/* save is done, now choose a new process or idle */
 sw1:
@@ -436,8 +442,11 @@ swtch_com:
 	movl	PCB_EIP(%edx),%eax
 	movl	%eax,(%esp)
 
-	movl	%ecx,_curproc			/* into next process */
 	movl	%edx,_curpcb
+	movl	%ecx,_curproc			/* into next process */
+
+	movb	PCB_INL(%edx),%al
+	movb	%al,_intr_nesting_level
 
 #ifdef	USER_LDT
 	cmpl	$0, PCB_USERLDT(%edx)
@@ -454,46 +463,12 @@ swtch_com:
 2:
 #endif
 
-	pushl	%edx				/* save p to return */
-/*
- * XXX - 0.0 forgot to save it - is that why this was commented out in 0.1?
- * I think restoring the cpl is unnecessary, but we must turn off the cli
- * now that spl*() don't do it as a side affect.
- */
-	pushl	PCB_IML(%edx)
 	sti
-#if 0
-	call	_splx
-#endif
-	addl	$4,%esp
-/*
- * XXX - 0.0 gets here via swtch_to_inactive().  I think 0.1 gets here in the
- * same way.  Better return a value.
- */
-	popl	%eax				/* return(p); */
 	ret
 
 ENTRY(mvesp)
 	movl	%esp,%eax
 	ret
-/*
- * struct proc *swtch_to_inactive(struct proc *p);
- *
- * At exit of a process, move off the address space of the
- * process and onto a "safe" one. Then, on a temporary stack
- * return and run code that disposes of the old state.
- * Since this code requires a parameter from the "old" stack,
- * pass it back as a return value.
- */
-ENTRY(swtch_to_inactive)
-	popl	%edx				/* old pc */
-	popl	%eax				/* arg, our return value */
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3			/* good bye address space */
- #write buffer?
-	movl	$tmpstk,%esp			/* temporary stack, compensated for call */
-	MEXITCOUNT
-	jmp	%edx				/* return, execute remainder of cleanup */
 
 /*
  * savectx(pcb, altreturn)
@@ -502,8 +477,6 @@ ENTRY(swtch_to_inactive)
  */
 ENTRY(savectx)
 	movl	4(%esp),%ecx
-	movw	_cpl,%ax
-	movw	%ax,PCB_IML(%ecx)
 	movl	(%esp),%eax
 	movl	%eax,PCB_EIP(%ecx)
 	movl	%ebx,PCB_EBX(%ecx)
diff --git a/sys/i386/include/cpu.h b/sys/i386/include/cpu.h
index 79c80af109d2..5d4ce70bc11f 100644
--- a/sys/i386/include/cpu.h
+++ b/sys/i386/include/cpu.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)cpu.h	5.4 (Berkeley) 5/9/91
- *	$Id: cpu.h,v 1.16 1994/11/05 22:44:34 bde Exp $
+ *	$Id: cpu.h,v 1.17 1994/11/26 09:27:58 phk Exp $
  */
 
 #ifndef _MACHINE_CPU_H_
@@ -58,8 +58,8 @@
 #define cpu_set_init_frame(p, fp)	(p)->p_md.md_regs = fp
 
 #define	CLKF_USERMODE(framep)	(ISPL((framep)->cf_cs) == SEL_UPL)
-#define CLKF_INTR(framep)	(0)
-#if 0
+#define CLKF_INTR(framep)	(intr_nesting_level >= 2)
+#if 1
 /*
  * XXX splsoftclock() is very broken and barely worth fixing.  It doesn't
  * turn off the clock bit in imen or in the icu.  (This is not a serious
@@ -127,6 +127,7 @@ struct cpu_nameclass {
 extern int	bootverbose;
 extern int	cpu;
 extern int	cpu_class;
+extern u_char	intr_nesting_level;
 extern struct cpu_nameclass i386_cpus[];
 extern int	want_resched;	/* resched was called */
 
diff --git a/sys/i386/include/pcb.h b/sys/i386/include/pcb.h
index 37b76f85832d..8ce7febb5ada 100644
--- a/sys/i386/include/pcb.h
+++ b/sys/i386/include/pcb.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)pcb.h	5.10 (Berkeley) 5/12/91
- *	$Id: pcb.h,v 1.6 1994/08/13 03:49:50 wollman Exp $
+ *	$Id: pcb.h,v 1.7 1994/10/08 22:21:33 phk Exp $
  */
 
 #ifndef _I386_PCB_H_
@@ -73,10 +73,10 @@ struct pcb {
 #endif
 #define	FP_USESEMC	0x08	/* process uses EMC memory-mapped mode */
 #define	FP_SOFTFP	0x20	/* process using software fltng pnt emulator */
-	short	pcb_iml;	/* interrupt mask level */
+	u_char	pcb_inl;	/* intr_nesting_level at context switch */
 	caddr_t	pcb_onfault;	/* copyin/out fault recovery */
 	long	pcb_sigc[8];	/* XXX signal code trampoline */
-	int	pcb_cmap2;	/* XXX temporary PTE - will prefault instead */
+	int	pad2;		/* XXX unused - remove it if you change struct */
 };
 
 /*
diff --git a/sys/i386/isa/icu.s b/sys/i386/isa/icu.s
index bd0d014c4918..c8cf81b2139c 100644
--- a/sys/i386/isa/icu.s
+++ b/sys/i386/isa/icu.s
@@ -36,7 +36,7 @@
  *
  *	@(#)icu.s	7.2 (Berkeley) 5/21/91
  *
- *	$Id: icu.s,v 1.14 1994/09/19 22:24:31 wollman Exp $
+ *	$Id: icu.s,v 1.15 1994/09/20 21:35:47 bde Exp $
  */
 
 /*
@@ -102,6 +102,7 @@ doreti_next:
 	jne	doreti_unpend
 doreti_exit:
 	movl	%eax,_cpl
+	decb	_intr_nesting_level
 	MEXITCOUNT
 	popl	%es
 	popl	%ds
diff --git a/sys/i386/isa/vector.s b/sys/i386/isa/vector.s
index 1bc2324f62d9..fcd0a7711d2a 100644
--- a/sys/i386/isa/vector.s
+++ b/sys/i386/isa/vector.s
@@ -1,6 +1,6 @@
 /*
  *	from: vector.s, 386BSD 0.1 unknown origin
- *	$Id: vector.s,v 1.9 1994/09/20 21:35:49 bde Exp $
+ *	$Id: vector.s,v 1.10 1994/11/01 23:29:50 bde Exp $
  */
 
 #include <i386/isa/icu.h>
@@ -147,6 +147,7 @@ IDTVEC(fastintr/**/irq_num) ; \
 	movl	(2+8+1)*4(%esp),%eax ;	/* ... cpl from thin frame */ \
 	pushl	%eax ; \
 	subl	$4,%esp ;	/* junk for unit number */ \
+	incb	_intr_nesting_level ; \
 	MEXITCOUNT ; \
 	jmp	_doreti
 
@@ -172,7 +173,7 @@ IDTVEC(intr/**/irq_num) ; \
 	movl	_cpl,%eax ; \
 	testb	$IRQ_BIT(irq_num),%reg ; \
 	jne	2f ; \
-1: ; \
+	incb	_intr_nesting_level ; \
 Xresume/**/irq_num: ; \
 	FAKE_MCOUNT(12*4(%esp)) ;	/* XXX late to avoid double count */ \
 	movl	_intr_countp + (irq_num) * 4,%eax ; \
@@ -254,6 +255,10 @@ imasks:				/* masks for interrupt handlers */
 	.space	NHWI*4		/* padding; HWI masks are elsewhere */
 	.long	SWI_TTY_MASK, SWI_NET_MASK, 0, 0, 0, 0, 0, 0
 	.long	0, 0, 0, 0, 0, 0, SWI_CLOCK_MASK, SWI_AST_MASK
+	.globl	_intr_nesting_level
+_intr_nesting_level:
+	.byte	0
+	.space	3
 
 /*
  * Interrupt counters and names.  The format of these and the label names