ref: f88a55e79b5bf656e7f9578d1318a955b9a4963a
dir: /sys/src/9/pc/fpu.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "ureg.h"
enum {
CR4Osfxsr = 1 << 9,
CR4Oxmmex = 1 << 10,
CR4Oxsave = 1 << 18,
};
/* from l.s */
extern void fpsserestore(FPsave*);
extern void fpssesave(FPsave*);
extern void fpx87restore0(FPsave*);
extern void fpx87save0(FPsave*);
extern void ldmxcsr(ulong);
void
putxcr0(ulong)
{
}
/*
* we keep FPsave structure in SSE format emulating FXSAVE / FXRSTOR
* instructions for legacy x87 fpu.
*/
static void
fpx87save(FPsave *fps)
{
ushort tag;
fpx87save0(fps);
/*
* convert x87 tag word to fxsave tag byte:
* 00, 01, 10 -> 1, 11 -> 0
*/
tag = ~fps->tag;
tag = (tag | (tag >> 1)) & 0x5555;
tag = (tag | (tag >> 1)) & 0x3333;
tag = (tag | (tag >> 2)) & 0x0F0F;
tag = (tag | (tag >> 4)) & 0x00FF;
/* NOP fps->fcw = fps->control; */
fps->fsw = fps->status;
fps->ftw = tag;
fps->fop = fps->opcode;
fps->fpuip = fps->pc;
fps->cs = fps->selector;
fps->fpudp = fps->operand;
fps->ds = fps->oselector;
#define MOVA(d,s) \
*((ushort*)(d+8)) = *((ushort*)(s+8)), \
*((ulong*)(d+4)) = *((ulong*)(s+4)), \
*((ulong*)(d)) = *((ulong*)(s))
MOVA(fps->xregs+0x70, fps->regs+70);
MOVA(fps->xregs+0x60, fps->regs+60);
MOVA(fps->xregs+0x50, fps->regs+50);
MOVA(fps->xregs+0x40, fps->regs+40);
MOVA(fps->xregs+0x30, fps->regs+30);
MOVA(fps->xregs+0x20, fps->regs+20);
MOVA(fps->xregs+0x10, fps->regs+10);
MOVA(fps->xregs+0x00, fps->regs+00);
#undef MOVA
#define CLR6(d) \
*((ulong*)(d)) = 0, \
*((ushort*)(d+4)) = 0
CLR6(fps->xregs+0x70+10);
CLR6(fps->xregs+0x60+10);
CLR6(fps->xregs+0x50+10);
CLR6(fps->xregs+0x40+10);
CLR6(fps->xregs+0x30+10);
CLR6(fps->xregs+0x20+10);
CLR6(fps->xregs+0x10+10);
CLR6(fps->xregs+0x00+10);
#undef CLR6
fps->rsrvd1 = fps->rsrvd2 = fps->mxcsr = fps->mxcsr_mask = 0;
}
static void
fpx87restore(FPsave *fps)
{
ushort msk, tos, tag, *reg;
/* convert fxsave tag byte to x87 tag word */
tag = 0;
tos = 7 - ((fps->fsw >> 11) & 7);
for(msk = 0x80; msk != 0; tos--, msk >>= 1){
tag <<= 2;
if((fps->ftw & msk) != 0){
reg = (ushort*)&fps->xregs[(tos & 7) << 4];
switch(reg[4] & 0x7fff){
case 0x0000:
if((reg[0] | reg[1] | reg[2] | reg[3]) == 0){
tag |= 1; /* 01 zero */
break;
}
/* no break */
case 0x7fff:
tag |= 2; /* 10 special */
break;
default:
if((reg[3] & 0x8000) == 0)
break; /* 00 valid */
tag |= 2; /* 10 special */
break;
}
}else{
tag |= 3; /* 11 empty */
}
}
#define MOVA(d,s) \
*((ulong*)(d)) = *((ulong*)(s)), \
*((ulong*)(d+4)) = *((ulong*)(s+4)), \
*((ushort*)(d+8)) = *((ushort*)(s+8))
MOVA(fps->regs+00, fps->xregs+0x00);
MOVA(fps->regs+10, fps->xregs+0x10);
MOVA(fps->regs+20, fps->xregs+0x20);
MOVA(fps->regs+30, fps->xregs+0x30);
MOVA(fps->regs+40, fps->xregs+0x40);
MOVA(fps->regs+50, fps->xregs+0x50);
MOVA(fps->regs+60, fps->xregs+0x60);
MOVA(fps->regs+70, fps->xregs+0x70);
#undef MOVA
fps->oselector = fps->ds;
fps->operand = fps->fpudp;
fps->opcode = fps->fop & 0x7ff;
fps->selector = fps->cs;
fps->pc = fps->fpuip;
fps->tag = tag;
fps->status = fps->fsw;
/* NOP fps->control = fps->fcw; */
fps->r1 = fps->r2 = fps->r3 = fps->r4 = 0;
fpx87restore0(fps);
}
static char* mathmsg[] =
{
nil, /* handled below */
"denormalized operand",
"division by zero",
"numeric overflow",
"numeric underflow",
"precision loss",
};
static void
mathnote(ulong status, ulong pc)
{
char *msg, note[ERRMAX];
int i;
/*
* Some attention should probably be paid here to the
* exception masks and error summary.
*/
msg = "unknown exception";
for(i = 1; i <= 5; i++){
if(!((1<<i) & status))
continue;
msg = mathmsg[i];
break;
}
if(status & 0x01){
if(status & 0x40){
if(status & 0x200)
msg = "stack overflow";
else
msg = "stack underflow";
}else
msg = "invalid operation";
}
snprint(note, sizeof note, "sys: fp: %s fppc=0x%lux status=0x%lux",
msg, pc, status);
postnote(up, 1, note, NDebug);
}
/*
* math coprocessor error
*/
static void
matherror(Ureg*, void*)
{
/*
* a write cycle to port 0xF0 clears the interrupt latch attached
* to the error# line from the 387
*/
if(!(m->cpuiddx & Fpuonchip))
outb(0xF0, 0xFF);
/*
* get floating point state to check out error
*/
fpsave(up->fpsave);
up->fpstate = FPinactive;
mathnote(up->fpsave->fsw, up->fpsave->fpuip);
}
/*
* SIMD error
*/
static void
simderror(Ureg *ureg, void*)
{
fpsave(up->fpsave);
up->fpstate = FPinactive;
mathnote(up->fpsave->mxcsr & 0x3f, ureg->pc);
}
/*
* math coprocessor emulation fault
*/
static void
mathemu(Ureg *ureg, void*)
{
ulong status, control;
if(up->fpstate & FPillegal){
/* someone did floating point in a note handler */
postnote(up, 1, "sys: floating point in note handler", NDebug);
return;
}
switch(up->fpstate){
case FPinit:
fpinit();
if(fpsave == fpssesave)
ldmxcsr(0x1f80); /* no simd exceptions on 386 */
while(up->fpsave == nil)
up->fpsave = mallocalign(sizeof(FPsave), FPalign, 0, 0);
up->fpstate = FPactive;
break;
case FPinactive:
/*
* Before restoring the state, check for any pending
* exceptions, there's no way to restore the state without
* generating an unmasked exception.
* More attention should probably be paid here to the
* exception masks and error summary.
*/
status = up->fpsave->fsw;
control = up->fpsave->fcw;
if((status & ~control) & 0x07F){
mathnote(status, up->fpsave->fpuip);
break;
}
fprestore(up->fpsave);
up->fpstate = FPactive;
break;
case FPactive:
panic("math emu pid %ld %s pc 0x%lux",
up->pid, up->text, ureg->pc);
break;
}
}
/*
* math coprocessor segment overrun
*/
static void
mathover(Ureg*, void*)
{
pexit("math overrun", 0);
}
void
mathinit(void)
{
trapenable(VectorCERR, matherror, 0, "matherror");
if(m->cpuidfamily == 3)
intrenable(IrqIRQ13, matherror, 0, BUSUNKNOWN, "matherror");
trapenable(VectorCNA, mathemu, 0, "mathemu");
trapenable(VectorCSO, mathover, 0, "mathover");
trapenable(VectorSIMD, simderror, 0, "simderror");
}
/*
* fpuinit(), called from cpuidentify() for each cpu.
*/
void
fpuinit(void)
{
uintptr cr4;
m->xcr0 = 0;
cr4 = getcr4();
cr4 &= ~CR4Oxsave;
if((m->cpuiddx & (Sse|Fxsr)) == (Sse|Fxsr)){ /* have sse fp? */
cr4 |= CR4Osfxsr|CR4Oxmmex;
putcr4(cr4);
fpsave = fpssesave;
fprestore = fpsserestore;
} else {
cr4 &= ~(CR4Osfxsr|CR4Oxmmex);
putcr4(cr4);
fpsave = fpx87save;
fprestore = fpx87restore;
}
fpoff();
}
void
fpuprocsetup(Proc *p)
{
p->fpstate = FPinit;
fpoff();
}
void
fpuprocfork(Proc *p)
{
int s;
s = splhi();
switch(up->fpstate & ~FPillegal){
case FPactive:
fpsave(up->fpsave);
up->fpstate = FPinactive;
case FPinactive:
while(p->fpsave == nil)
p->fpsave = mallocalign(sizeof(FPsave), FPalign, 0, 0);
memmove(p->fpsave, up->fpsave, sizeof(FPsave));
p->fpstate = FPinactive;
}
splx(s);
}
void
fpuprocsave(Proc *p)
{
if(p->fpstate == FPactive){
if(p->state == Moribund)
fpclear();
else{
/*
* Fpsave() stores without handling pending
* unmasked exeptions. Postnote() can't be called
* so the handling of pending exceptions is delayed
* until the process runs again and generates an
* emulation fault to activate the FPU.
*/
fpsave(p->fpsave);
}
p->fpstate = FPinactive;
}
}
void
fpuprocrestore(Proc*)
{
}