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Major rewrite of npx code (npx-0.5 + 2 patches to it)
[unix-history] / usr / src / sys.386bsd / i386 / isa / npx.c
/*-
* Copyright (c) 1990 William Jolitz.
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)npx.c 7.2 (Berkeley) 5/12/91
*
* PATCHES MAGIC LEVEL PATCH THAT GOT US HERE
* -------------------- ----- ----------------------
* CURRENT PATCH LEVEL: 1 00154
* -------------------- ----- ----------------------
*
* 20 Apr 93 Bruce Evans New npx-0.5 code
* 23 May 93 Rodney W. Grimes Return a special value of -1 from
* the probe code to keep isa_config from
* printing out the I/O address when we
* are using trap 16 handling.
*
*/
static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/npx.c,v 1.2 92/01/21 14:34:27 william Exp $";
#include "npx.h"
#if NNPX > 0
#include "param.h"
#include "systm.h"
#include "conf.h"
#include "file.h"
#include "proc.h"
#include "machine/cpu.h"
#include "machine/pcb.h"
#include "machine/trap.h"
#include "ioctl.h"
#include "machine/specialreg.h"
#include "i386/isa/icu.h"
#include "i386/isa/isa_device.h"
#include "i386/isa/isa.h"
/*
* 387 and 287 Numeric Coprocessor Extension (NPX) Driver.
*/
#ifdef __GNUC__
#define disable_intr() __asm("cli")
#define enable_intr() __asm("sti")
#define fldcw(addr) __asm("fldcw %0" : : "m" (*addr))
#define fnclex() __asm("fnclex")
#define fninit() __asm("fninit")
#define fnsave(addr) __asm("fnsave %0" : "=m" (*addr) : "0" (*addr))
#define fnstcw(addr) __asm("fnstcw %0" : "=m" (*addr) : "0" (*addr))
#define fnstsw(addr) __asm("fnstsw %0" : "=m" (*addr) : "0" (*addr))
#define fp_divide_by_0() __asm("fldz; fld1; fdiv %st,%st(1); fwait")
#define frstor(addr) __asm("frstor %0" : : "m" (*addr))
#define fwait() __asm("fwait")
#define read_eflags() ({u_long ef; \
__asm("pushf; popl %0" : "=a" (ef)); \
ef; })
#define start_emulating() __asm("smsw %%ax; orb %0,%%al; lmsw %%ax" \
: : "n" (CR0_TS) : "ax")
#define stop_emulating() __asm("clts")
#define write_eflags(ef) __asm("pushl %0; popf" : : "a" ((u_long) ef))
#else /* not __GNUC__ */
void disable_intr __P((void));
void enable_intr __P((void));
void fldcw __P((caddr_t addr));
void fnclex __P((void));
void fninit __P((void));
void fnsave __P((caddr_t addr));
void fnstcw __P((caddr_t addr));
void fnstsw __P((caddr_t addr));
void fp_divide_by_0 __P((void));
void frstor __P((caddr_t addr));
void fwait __P((void));
u_long read_eflags __P((void));
void start_emulating __P((void));
void stop_emulating __P((void));
void write_eflags __P((u_long ef));
#endif /* __GNUC__ */
typedef u_char bool_t;
extern struct gate_descriptor idt[];
int npxdna __P((void));
void npxexit __P((struct proc *p));
void npxinit __P((u_int control));
void npxintr __P((struct intrframe frame));
void npxsave __P((struct save87 *addr));
static int npxattach __P((struct isa_device *dvp));
static int npxprobe __P((struct isa_device *dvp));
static int npxprobe1 __P((struct isa_device *dvp));
struct isa_driver npxdriver = {
npxprobe, npxattach, "npx",
};
u_int npx0mask;
struct proc *npxproc;
static bool_t npx_ex16;
static bool_t npx_exists;
static struct gate_descriptor npx_idt_probeintr;
static int npx_intrno;
static volatile u_int npx_intrs_while_probing;
static bool_t npx_irq13;
static volatile u_int npx_traps_while_probing;
/*
* Special interrupt handlers. Someday intr0-intr15 will be used to count
* interrupts. We'll still need a special exception 16 handler. The busy
* latch stuff in probintr() can be moved to npxprobe().
*/
void probeintr(void);
asm
("
.text
_probeintr:
ss
incl _npx_intrs_while_probing
pushl %eax
movb $0x20,%al /* EOI (asm in strings loses cpp features) */
outb %al,$0xa0 /* IO_ICU2 */
outb %al,$0x20 /* IO_ICU1 */
movb $0,%al
outb %al,$0xf0 /* clear BUSY# latch */
popl %eax
iret
");
void probetrap(void);
asm
("
.text
_probetrap:
ss
incl _npx_traps_while_probing
fnclex
iret
");
/*
* Probe routine. Initialize cr0 to give correct behaviour for [f]wait
* whether the device exists or not (XXX should be elsewhere). Set flags
* to tell npxattach() what to do. Modify device struct if npx doesn't
* need to use interrupts. Return 1 if device exists.
*/
static int
npxprobe(dvp)
struct isa_device *dvp;
{
int result;
u_long save_eflags;
u_char save_icu1_mask;
u_char save_icu2_mask;
struct gate_descriptor save_idt_npxintr;
struct gate_descriptor save_idt_npxtrap;
/*
* This routine is now just a wrapper for npxprobe1(), to install
* special npx interrupt and trap handlers, to enable npx interrupts
* and to disable other interrupts. Someday isa_configure() will
* install suitable handlers and run with interrupts enabled so we
* won't need to do so much here.
*/
npx_intrno = NRSVIDT + ffs(dvp->id_irq) - 1;
save_eflags = read_eflags();
disable_intr();
save_icu1_mask = inb(IO_ICU1 + 1);
save_icu2_mask = inb(IO_ICU2 + 1);
save_idt_npxintr = idt[npx_intrno];
save_idt_npxtrap = idt[16];
outb(IO_ICU1 + 1, ~(IRQ_SLAVE | dvp->id_irq));
outb(IO_ICU2 + 1, ~(dvp->id_irq >> 8));
setidt(16, probetrap, SDT_SYS386TGT, SEL_KPL);
setidt(npx_intrno, probeintr, SDT_SYS386IGT, SEL_KPL);
npx_idt_probeintr = idt[npx_intrno];
enable_intr();
result = npxprobe1(dvp);
disable_intr();
outb(IO_ICU1 + 1, save_icu1_mask);
outb(IO_ICU2 + 1, save_icu2_mask);
idt[npx_intrno] = save_idt_npxintr;
idt[16] = save_idt_npxtrap;
write_eflags(save_eflags);
return (result);
}
static int
npxprobe1(dvp)
struct isa_device *dvp;
{
int control;
int status;
#ifdef lint
npxintr();
#endif
/*
* Partially reset the coprocessor, if any. Some BIOS's don't reset
* it after a warm boot.
*/
outb(0xf1, 0); /* full reset on some systems, NOP on others */
outb(0xf0, 0); /* clear BUSY# latch */
/*
* Prepare to trap all ESC (i.e., NPX) instructions and all WAIT
* instructions. We must set the CR0_MP bit and use the CR0_TS
* bit to control the trap, because setting the CR0_EM bit does
* not cause WAIT instructions to trap. It's important to trap
* WAIT instructions - otherwise the "wait" variants of no-wait
* control instructions would degenerate to the "no-wait" variants
* after FP context switches but work correctly otherwise. It's
* particularly important to trap WAITs when there is no NPX -
* otherwise the "wait" variants would always degenerate.
*
* Try setting CR0_NE to get correct error reporting on 486DX's.
* Setting it should fail or do nothing on lesser processors.
*/
load_cr0(rcr0() | CR0_MP | CR0_NE);
/*
* But don't trap while we're probing.
*/
stop_emulating();
/*
* Finish resetting the coprocessor, if any. If there is an error
* pending, then we may get a bogus IRQ13, but probeintr() will handle
* it OK. Bogus halts have never been observed, but we enabled
* IRQ13 and cleared the BUSY# latch early to handle them anyway.
*/
fninit();
DELAY(1000); /* wait for any IRQ13 (fwait might hang) */
#ifdef DIAGNOSTIC
if (npx_intrs_while_probing != 0)
printf("fninit caused %u bogus npx interrupt(s)\n",
npx_intrs_while_probing);
if (npx_traps_while_probing != 0)
printf("fninit caused %u bogus npx trap(s)\n",
npx_traps_while_probing);
#endif
/*
* Check for a status of mostly zero.
*/
status = 0x5a5a;
fnstsw(&status);
if ((status & 0xb8ff) == 0) {
/*
* Good, now check for a proper control word.
*/
control = 0x5a5a;
fnstcw(&control);
if ((control & 0x1f3f) == 0x033f) {
npx_exists = 1;
/*
* We have an npx, now divide by 0 to see if exception
* 16 works.
*/
control &= ~(1 << 2); /* enable divide by 0 trap */
fldcw(&control);
npx_traps_while_probing = npx_intrs_while_probing = 0;
fp_divide_by_0();
if (npx_traps_while_probing != 0) {
/*
* Good, exception 16 works.
*/
npx_ex16 = 1;
dvp->id_irq = 0; /* zap the interrupt */
/*
* special return value to flag that we do not
* actually use any I/O registers
*/
return (-1);
}
if (npx_intrs_while_probing != 0) {
/*
* Bad, we are stuck with IRQ13.
*/
npx_irq13 = 1;
npx0mask = dvp->id_irq; /* npxattach too late */
return (IO_NPXSIZE);
}
/*
* Worse, even IRQ13 is broken. Use emulator.
*/
}
}
/*
* Probe failed, but we want to get to npxattach to initialize the
* emulator and say that it has been installed. XXX handle devices
* that aren't really devices better.
*/
dvp->id_irq = 0;
return (IO_NPXSIZE);
}
/*
* Attach routine - announce which it is, and wire into system
*/
int
npxattach(dvp)
struct isa_device *dvp;
{
if (npx_ex16)
printf(" <Errors reported via Exception 16>");
else if (npx_irq13)
printf(" <Errors reported via IRQ 13>");
else if (npx_exists)
printf(" <Error reporting broken, using 387 emulator>");
else
printf(" <387 Emulator>");
npxinit(__INITIAL_NPXCW__);
return (1); /* XXX unused */
}
/*
* Initialize floating point unit.
*/
void
npxinit(control)
u_int control;
{
struct save87 dummy;
if (!npx_exists)
return;
/*
* fninit has the same h/w bugs as fnsave. Use the detoxified
* fnsave to throw away any junk in the fpu. fnsave initializes
* the fpu and sets npxproc = NULL as important side effects.
*/
npxsave(&dummy);
stop_emulating();
fldcw(&control);
if (curpcb != NULL)
fnsave(&curpcb->pcb_savefpu);
start_emulating();
}
/*
* Free coprocessor (if we have it).
*/
void
npxexit(p)
struct proc *p;
{
if (p == npxproc) {
start_emulating();
npxproc = NULL;
}
}
/*
* Record the FPU state and reinitialize it all except for the control word.
* Then generate a SIGFPE.
*
* Reinitializing the state allows naive SIGFPE handlers to longjmp without
* doing any fixups.
*
* XXX there is currently no way to pass the full error state to signal
* handlers, and if this is a nested interrupt there is no way to pass even
* a status code! So there is no way to have a non-naive SIGFPE handler. At
* best a handler could do an fninit followed by an fldcw of a static value.
* fnclex would be of little use because it would leave junk on the FPU stack.
* Returning from the handler would be even less safe than usual because
* IRQ13 exception handling makes exceptions even less precise than usual.
*/
void
npxintr(frame)
struct intrframe frame;
{
int code;
if (npxproc == NULL || !npx_exists) {
/* XXX no %p in stand/printf.c. Cast to quiet gcc -Wall. */
printf("npxintr: npxproc = %lx, curproc = %lx, npx_exists = %d\n",
(u_long) npxproc, (u_long) curproc, npx_exists);
panic("npxintr from nowhere");
}
if (npxproc != curproc) {
printf("npxintr: npxproc = %lx, curproc = %lx, npx_exists = %d\n",
(u_long) npxproc, (u_long) curproc, npx_exists);
panic("npxintr from non-current process");
}
/*
* Save state. This does an implied fninit. It had better not halt
* the cpu or we'll hang.
*/
outb(0xf0, 0);
fnsave(&curpcb->pcb_savefpu);
fwait();
/*
* Restore control word (was clobbered by fnsave).
*/
fldcw(&curpcb->pcb_savefpu.sv_env.en_cw);
fwait();
/*
* Remember the exception status word and tag word. The current
* (almost fninit'ed) fpu state is in the fpu and the exception
* state just saved will soon be junk. However, the implied fninit
* doesn't change the error pointers or register contents, and we
* preserved the control word and will copy the status and tag
* words, so the complete exception state can be recovered.
*/
curpcb->pcb_savefpu.sv_ex_sw = curpcb->pcb_savefpu.sv_env.en_sw;
curpcb->pcb_savefpu.sv_ex_tw = curpcb->pcb_savefpu.sv_env.en_tw;
/*
* Pass exception to process.
*/
if (ISPL(frame.if_cs) == SEL_UPL) {
/*
* Interrupt is essentially a trap, so we can afford to call
* the SIGFPE handler (if any) as soon as the interrupt
* returns.
*
* XXX little or nothing is gained from this, and plenty is
* lost - the interrupt frame has to contain the trap frame
* (this is otherwise only necessary for the rescheduling trap
* in doreti, and the frame for that could easily be set up
* just before it is used).
*/
curproc->p_regs = (int *)&frame.if_es;
curpcb->pcb_flags |= FM_TRAP; /* used by sendsig */
#ifdef notyet
/*
* Encode the appropriate code for detailed information on
* this exception.
*/
code = XXX_ENCODE(curpcb->pcb_savefpu.sv_ex_sw);
#else
code = 0; /* XXX */
#endif
trapsignal(curproc, SIGFPE, code);
curpcb->pcb_flags &= ~FM_TRAP;
} else {
/*
* Nested interrupt. These losers occur when:
* o an IRQ13 is bogusly generated at a bogus time, e.g.:
* o immediately after an fnsave or frstor of an
* error state.
* o a couple of 386 instructions after
* "fstpl _memvar" causes a stack overflow.
* These are especially nasty when combined with a
* trace trap.
* o an IRQ13 occurs at the same time as another higher-
* priority interrupt.
*
* Treat them like a true async interrupt.
*/
psignal(npxproc, SIGFPE);
}
}
/*
* Implement device not available (DNA) exception
*
* It would be better to switch FP context here (only). This would require
* saving the state in the proc table instead of in the pcb.
*/
int
npxdna()
{
if (!npx_exists)
return (0);
if (npxproc != NULL) {
printf("npxdna: npxproc = %lx, curproc = %lx\n",
(u_long) npxproc, (u_long) curproc);
panic("npxdna");
}
stop_emulating();
/*
* Record new context early in case frstor causes an IRQ13.
*/
npxproc = curproc;
/*
* The following frstor may cause an IRQ13 when the state being
* restored has a pending error. The error will appear to have been
* triggered by the current (npx) user instruction even when that
* instruction is a no-wait instruction that should not trigger an
* error (e.g., fnclex). On at least one 486 system all of the
* no-wait instructions are broken the same as frstor, so our
* treatment does not amplify the breakage. On at least one
* 386/Cyrix 387 system, fnclex works correctly while frstor and
* fnsave are broken, so our treatment breaks fnclex if it is the
* first FPU instruction after a context switch.
*/
frstor(&curpcb->pcb_savefpu);
return (1);
}
/*
* Wrapper for fnsave instruction to handle h/w bugs. If there is an error
* pending, then fnsave generates a bogus IRQ13 on some systems. Force
* any IRQ13 to be handled immediately, and then ignore it. This routine is
* often called at splhigh so it must not use many system services. In
* particular, it's much easier to install a special handler than to
* guarantee that it's safe to use npxintr() and its supporting code.
*/
void
npxsave(addr)
struct save87 *addr;
{
u_char icu1_mask;
u_char icu2_mask;
u_char old_icu1_mask;
u_char old_icu2_mask;
struct gate_descriptor save_idt_npxintr;
disable_intr();
old_icu1_mask = inb(IO_ICU1 + 1);
old_icu2_mask = inb(IO_ICU2 + 1);
save_idt_npxintr = idt[npx_intrno];
outb(IO_ICU1 + 1, old_icu1_mask & ~(IRQ_SLAVE | npx0mask));
outb(IO_ICU2 + 1, old_icu2_mask & ~(npx0mask >> 8));
idt[npx_intrno] = npx_idt_probeintr;
enable_intr();
stop_emulating();
fnsave(addr);
fwait();
start_emulating();
npxproc = NULL;
disable_intr();
icu1_mask = inb(IO_ICU1 + 1); /* masks may have changed */
icu2_mask = inb(IO_ICU2 + 1);
outb(IO_ICU1 + 1,
(icu1_mask & ~npx0mask) | (old_icu1_mask & npx0mask));
outb(IO_ICU2 + 1,
(icu2_mask & ~(npx0mask >> 8))
| (old_icu2_mask & (npx0mask >> 8)));
idt[npx_intrno] = save_idt_npxintr;
enable_intr(); /* back to usual state */
}
#endif /* NNPX > 0 */
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.