ref: 1c7e58e75bc6b5620984f164d66354350b28dfe0
dir: /sys/src/9/pc64/fpu.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "ureg.h"
#include "io.h"
enum {
CR4Osfxsr = 1 << 9,
CR4Oxmmex = 1 << 10,
CR4Oxsave = 1 << 18,
};
/*
* SIMD Floating Point.
* Assembler support to get at the individual instructions
* is in l.s.
*/
extern void _clts(void);
extern void _fldcw(u16int);
extern void _fnclex(void);
extern void _fninit(void);
extern void _fxrstor(void*);
extern void _fxsave(void*);
extern void _xrstor(void*);
extern void _xsave(void*);
extern void _xsaveopt(void*);
extern void _fwait(void);
extern void _ldmxcsr(u32int);
extern void _stts(void);
static void mathemu(Ureg *ureg, void*);
static void
fpssesave(FPsave *s)
{
_fxsave(s);
_stts();
}
static void
fpsserestore(FPsave *s)
{
_clts();
_fxrstor(s);
}
static void
fpxsave(FPsave *s)
{
_xsave(s);
_stts();
}
static void
fpxrestore(FPsave *s)
{
_clts();
_xrstor(s);
}
static void
fpxsaves(FPsave *s)
{
_xsaveopt(s);
_stts();
}
static void
fpxrestores(FPsave *s)
{
_clts();
_xrstor(s);
}
static void
fpxsaveopt(FPsave *s)
{
_xsaveopt(s);
_stts();
}
/*
* Turn the FPU on and initialise it for use.
* Set the precision and mask the exceptions
* we don't care about from the generic Mach value.
*/
void
fpinit(void)
{
_clts();
_fninit();
_fwait();
_fldcw(0x0232);
_ldmxcsr(0x1900);
}
static char* mathmsg[] =
{
nil, /* handled below */
"denormalized operand",
"division by zero",
"numeric overflow",
"numeric underflow",
"precision loss",
};
static void
mathnote(ulong status, uintptr pc, int kernel)
{
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=%#p status=0x%lux", msg, pc, status);
if(kernel)
panic("%s", note);
postnote(up, 1, note, NDebug);
}
/*
* math coprocessor error
*/
static void
matherror(Ureg *ureg, void*)
{
if(!userureg(ureg)){
if(up == nil)
mathnote(m->fpsave->fsw, m->fpsave->rip, 1);
else
mathnote(up->kfpsave->fsw, up->kfpsave->rip, 1);
return;
}
if(up->fpstate != FPinactive){
_clts();
fpsave(up->fpsave);
up->fpstate = FPinactive;
}
mathnote(up->fpsave->fsw, up->fpsave->rip, 0);
}
/*
* SIMD error
*/
static void
simderror(Ureg *ureg, void*)
{
if(!userureg(ureg)){
if(up == nil)
mathnote(m->fpsave->mxcsr & 0x3f, ureg->pc, 1);
else
mathnote(up->kfpsave->mxcsr & 0x3f, ureg->pc, 1);
return;
}
if(up->fpstate != FPinactive){
_clts();
fpsave(up->fpsave);
up->fpstate = FPinactive;
}
mathnote(up->fpsave->mxcsr & 0x3f, ureg->pc, 0);
}
/*
* math coprocessor segment overrun
*/
static void
mathover(Ureg *ureg, void*)
{
if(!userureg(ureg))
panic("math overrun");
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)
{
u64int cr4;
ulong regs[4];
m->xcr0 = 0;
cr4 = getcr4() | CR4Osfxsr|CR4Oxmmex;
if((m->cpuidcx & (Xsave|Avx)) == (Xsave|Avx) && getconf("*noavx") == nil){
cr4 |= CR4Oxsave;
putcr4(cr4);
m->xcr0 = 7; /* x87, sse, avx */
putxcr0(m->xcr0);
cpuid(0xd, 1, regs);
if(regs[0] & Xsaves){
fpsave = fpxsaves;
fprestore = fpxrestores;
} else {
if(regs[0] & Xsaveopt)
fpsave = fpxsaveopt;
else
fpsave = fpxsave;
fprestore = fpxrestore;
}
} else {
cr4 &= ~CR4Oxsave;
putcr4(cr4);
fpsave = fpssesave;
fprestore = fpsserestore;
}
m->fpsave = nil;
m->fpstate = FPinit;
_stts();
}
static FPsave*
fpalloc(void)
{
FPsave *save;
while((save = mallocalign(sizeof(FPsave), FPalign, 0, 0)) == nil){
spllo();
resrcwait("no memory for FPsave");
splhi();
}
return save;
}
static void
fpfree(FPsave *save)
{
free(save);
}
void
fpuprocsetup(Proc *p)
{
p->fpstate = FPinit;
}
void
fpuprocfork(Proc *p)
{
int s;
s = splhi();
switch(up->fpstate & ~FPillegal){
case FPprotected:
_clts();
/* wet floor */
case FPactive:
fpsave(up->fpsave);
up->fpstate = FPinactive;
/* wet floor */
case FPinactive:
if(p->fpsave == nil)
p->fpsave = fpalloc();
memmove(p->fpsave, up->fpsave, sizeof(FPsave));
p->fpstate = FPinactive;
}
splx(s);
}
void
fpuprocsave(Proc *p)
{
if(p->state == Moribund){
if(p->fpstate == FPactive || p->kfpstate == FPactive){
_fnclex();
_stts();
}
fpfree(p->fpsave);
fpfree(p->kfpsave);
p->fpsave = p->kfpsave = nil;
p->fpstate = p->kfpstate = FPinit;
return;
}
if(p->kfpstate == FPactive){
fpsave(p->kfpsave);
p->kfpstate = FPinactive;
return;
}
if(p->fpstate == FPprotected)
_clts();
else if(p->fpstate != FPactive)
return;
fpsave(p->fpsave);
p->fpstate = FPinactive;
}
void
fpuprocrestore(Proc*)
{
/*
* when the scheduler switches,
* we can discard its fp state.
*/
switch(m->fpstate){
case FPactive:
_fnclex();
_stts();
/* wet floor */
case FPinactive:
fpfree(m->fpsave);
m->fpsave = nil;
m->fpstate = FPinit;
}
}
/*
* Protect or save FPU state and setup new state
* (lazily in the case of user process) for the kernel.
* All syscalls, traps and interrupts (except mathemu()!)
* are handled between fpukenter() and fpukexit(),
* so they can use floating point and vector instructions.
*/
FPsave*
fpukenter(Ureg *)
{
if(up == nil){
switch(m->fpstate){
case FPactive:
fpsave(m->fpsave);
/* wet floor */
case FPinactive:
m->fpstate = FPinit;
return m->fpsave;
}
return nil;
}
switch(up->fpstate){
case FPactive:
up->fpstate = FPprotected;
_stts();
/* wet floor */
case FPprotected:
return nil;
}
switch(up->kfpstate){
case FPactive:
fpsave(up->kfpsave);
/* wet floor */
case FPinactive:
up->kfpstate = FPinit;
return up->kfpsave;
}
return nil;
}
void
fpukexit(Ureg *ureg, FPsave *save)
{
if(up == nil){
switch(m->fpstate){
case FPactive:
_fnclex();
_stts();
/* wet floor */
case FPinactive:
fpfree(m->fpsave);
m->fpstate = FPinit;
}
m->fpsave = save;
if(save != nil)
m->fpstate = FPinactive;
return;
}
if(up->fpstate == FPprotected){
if(userureg(ureg)){
up->fpstate = FPactive;
_clts();
}
return;
}
switch(up->kfpstate){
case FPactive:
_fnclex();
_stts();
/* wet floor */
case FPinactive:
fpfree(up->kfpsave);
up->kfpstate = FPinit;
}
up->kfpsave = save;
if(save != nil)
up->kfpstate = 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.
*/
static int
fpcheck(FPsave *save, int kernel)
{
ulong status, control;
status = save->fsw;
control = save->fcw;
if((status & ~control) & 0x07F){
mathnote(status, save->rip, kernel);
return 1;
}
return 0;
}
/*
* math coprocessor emulation fault
*/
static void
mathemu(Ureg *ureg, void*)
{
if(!userureg(ureg)){
if(up == nil){
switch(m->fpstate){
case FPinit:
m->fpsave = fpalloc();
m->fpstate = FPactive;
fpinit();
break;
case FPinactive:
fpcheck(m->fpsave, 1);
fprestore(m->fpsave);
m->fpstate = FPactive;
break;
default:
panic("floating point error in irq");
}
return;
}
if(up->fpstate == FPprotected){
_clts();
fpsave(up->fpsave);
up->fpstate = FPinactive;
}
switch(up->kfpstate){
case FPinit:
up->kfpsave = fpalloc();
up->kfpstate = FPactive;
fpinit();
break;
case FPinactive:
fpcheck(up->kfpsave, 1);
fprestore(up->kfpsave);
up->kfpstate = FPactive;
break;
default:
panic("floating point error in trap");
}
return;
}
if(up->fpstate & FPillegal){
postnote(up, 1, "sys: floating point in note handler", NDebug);
return;
}
switch(up->fpstate){
case FPinit:
if(up->fpsave == nil)
up->fpsave = fpalloc();
up->fpstate = FPactive;
fpinit();
break;
case FPinactive:
if(fpcheck(up->fpsave, 0))
break;
fprestore(up->fpsave);
up->fpstate = FPactive;
break;
case FPprotected:
up->fpstate = FPactive;
_clts();
break;
case FPactive:
postnote(up, 1, "sys: floating point error", NDebug);
break;
}
}