ref: fa18daa2f56b306b151781523e877bd07d62f799
dir: /os/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(u32);
extern void _stts(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();
}
static char* mathmsg[] =
{
nil, /* handled below */
"denormalized operand",
"division by zero",
"numeric overflow",
"numeric underflow",
"precision loss",
};
enum
{
NDebug, /* print debug message */
};
static void
mathnote(ulong status, uintptr 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=%#p status=0x%lux",
msg, pc, status);
postnote(up, 1, note, NDebug);
}
/*
* math coprocessor error
*/
static void
matherror(Ureg *, void*)
{
/*
* Save FPU state to check out the error.
*/
fpsave(up->fpsave);
up->fpstate = FPinactive | (up->fpstate & (FPnouser|FPkernel|FPindexm));
mathnote(up->fpsave->fsw, up->fpsave->rip);
}
/*
* SIMD error
*/
static void
simderror(Ureg *ureg, void*)
{
fpsave(up->fpsave);
up->fpstate = FPinactive | (up->fpstate & (FPnouser|FPkernel|FPindexm));
mathnote(up->fpsave->mxcsr & 0x3f, ureg->pc);
}
void
fpinit(void)
{
/*
* A process tries to use the FPU for the
* first time and generates a 'device not available'
* exception.
* 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.
*/
_clts();
_fninit();
_fwait();
_fldcw(0x0232);
_ldmxcsr(0x1900);
}
/*
* math coprocessor emulation fault
*/
static void
mathemu(Ureg *ureg, void*)
{
ulong status, control;
int index;
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 & ~(FPnouser|FPkernel|FPindexm)){
case FPactive | FPpush:
_clts();
fpsave(up->fpsave);
case FPinactive | FPpush:
up->fpstate += FPindex1;
case FPinit | FPpush:
case FPinit:
fpinit();
index = up->fpstate >> FPindexs;
if(index < 0 || index > (FPindexm>>FPindexs))
panic("fpslot index overflow: %d", index);
if(userureg(ureg)){
if(index != 0)
panic("fpslot index %d != 0 for user", index);
} else {
if(index == 0)
up->fpstate |= FPnouser;
up->fpstate |= FPkernel;
}
while(up->fpslot[index] == nil)
up->fpslot[index] = mallocalign(sizeof(FPsave), FPalign, 0, 0);
up->fpsave = up->fpslot[index];
up->fpstate = FPactive | (up->fpstate & (FPnouser|FPkernel|FPindexm));
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->rip);
break;
}
fprestore(up->fpsave);
up->fpstate = FPactive | (up->fpstate & (FPnouser|FPkernel|FPindexm));
break;
case FPactive:
panic("math emu pid %d %s pc %#p",
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)
{
u64 cr4;
u32 regs[4];
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 {
putcr4(cr4);
fpsave = fpssesave;
fprestore = fpsserestore;
}
}
void
fpuprocsetup(Proc *p)
{
p->fpstate = FPinit;
_stts();
}
void
fpuprocfork(Proc *p)
{
int s;
/* save floating point state */
s = splhi();
switch(up->fpstate & ~FPillegal){
case FPactive | FPpush:
_clts();
case FPactive:
fpsave(up->fpsave);
up->fpstate = FPinactive | (up->fpstate & FPpush);
case FPactive | FPkernel:
case FPinactive | FPkernel:
case FPinactive | FPpush:
case FPinactive:
while(p->fpslot[0] == nil)
p->fpslot[0] = mallocalign(sizeof(FPsave), FPalign, 0, 0);
memmove(p->fpsave = p->fpslot[0], up->fpslot[0], sizeof(FPsave));
p->fpstate = FPinactive;
}
splx(s);
}
void
fpuprocsave(Proc *p)
{
switch(p->fpstate & ~(FPnouser|FPkernel|FPindexm)){
case FPactive | FPpush:
_clts();
case FPactive:
if(p->state == Moribund){
_fnclex();
_stts();
break;
}
/*
* 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 | (p->fpstate & ~FPactive);
break;
}
}
void
fpuprocrestore(Proc*)
{
}
/*
* Fpusave and fpurestore lazily save and restore FPU state across
* system calls and the pagefault handler so that we can take
* advantage of SSE instructions such as AES-NI in the kernel.
*/
int
fpusave(void)
{
int ostate = up->fpstate;
if((ostate & ~(FPnouser|FPkernel|FPindexm)) == FPactive)
_stts();
up->fpstate = FPpush | (ostate & ~FPillegal);
return ostate;
}
void
fpurestore(int ostate)
{
int astate = up->fpstate;
if(astate == (FPpush | (ostate & ~FPillegal))){
if((ostate & ~(FPnouser|FPkernel|FPindexm)) == FPactive)
_clts();
} else {
if(astate == FPinit) /* don't restore on procexec()/procsetup() */
return;
if((astate & ~(FPnouser|FPkernel|FPindexm)) == FPactive)
_stts();
up->fpsave = up->fpslot[ostate>>FPindexs];
if(ostate & FPactive)
ostate = FPinactive | (ostate & ~FPactive);
}
up->fpstate = ostate;
}