/* $OpenBSD: npx.c,v 1.76 2024/05/13 01:15:50 jsg Exp $ */ /* $NetBSD: npx.c,v 1.57 1996/05/12 23:12:24 mycroft Exp $ */ #if 0 #define IPRINTF(x) printf x #else #define IPRINTF(x) #endif /*- * Copyright (c) 1994, 1995 Charles M. Hannum. All rights reserved. * 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. 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 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 387 and 287 Numeric Coprocessor Extension (NPX) Driver. * * We do lazy initialization and switching using the TS bit in cr0 and the * MDP_USEDFPU bit in mdproc. * * DNA exceptions are handled like this: * * 1) If there is no NPX, return and go to the emulator. * 2) If someone else has used the NPX, save its state into that process's PCB. * 3a) If MDP_USEDFPU is not set, set it and initialize the NPX. * 3b) Otherwise, reload the process's previous NPX state. * * When a process is created or exec()s, its saved cr0 image has the TS bit * set and the MDP_USEDFPU bit clear. The MDP_USEDFPU bit is set when the * process first gets a DNA and the NPX is initialized. The TS bit is turned * off when the NPX is used, and turned on again later when the process's NPX * state is saved. */ #define fldcw(addr) __asm("fldcw %0" : : "m" (*addr)) #define fnclex() __asm("fnclex") #define fninit() __asm("fninit") #define fnsave(addr) __asm("fnsave %0" : "=m" (*addr)) #define fnstcw(addr) __asm("fnstcw %0" : "=m" (*addr)) #define fnstsw(addr) __asm("fnstsw %0" : "=m" (*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 clts() __asm("clts") #define stts() lcr0(rcr0() | CR0_TS) /* * The mxcsr_mask for this host, taken from fxsave() on the primary CPU */ uint32_t fpu_mxcsr_mask; int npxintr(void *); static int npxprobe1(struct isa_attach_args *); static int x86fpflags_to_siginfo(u_int32_t); struct npx_softc { struct device sc_dev; void *sc_ih; }; int npxprobe(struct device *, void *, void *); void npxattach(struct device *, struct device *, void *); const struct cfattach npx_ca = { sizeof(struct npx_softc), npxprobe, npxattach }; struct cfdriver npx_cd = { NULL, "npx", DV_DULL }; enum npx_type { NPX_NONE = 0, NPX_INTERRUPT, NPX_EXCEPTION, NPX_BROKEN, NPX_CPUID, }; static enum npx_type npx_type; static volatile u_int npx_intrs_while_probing __attribute__((section(".kudata"))); static volatile u_int npx_traps_while_probing __attribute__((section(".kudata"))); #define fxsave(addr) __asm("fxsave %0" : "=m" (*addr)) #define fxrstor(addr) __asm("fxrstor %0" : : "m" (*addr)) #define ldmxcsr(addr) __asm("ldmxcsr %0" : : "m" (*addr)) static __inline void fpu_save(union savefpu *addr) { if (i386_use_fxsave) { fxsave(&addr->sv_xmm); /* FXSAVE doesn't FNINIT like FNSAVE does -- so do it here. */ fninit(); } else fnsave(&addr->sv_87); } static int npxdna_notset(struct cpu_info *ci) { panic("npxdna vector not initialized"); } int (*npxdna_func)(struct cpu_info *) = npxdna_notset; int npxdna_s87(struct cpu_info *); int npxdna_xmm(struct cpu_info *); /* * 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\n\t" "probeintr:\n\t" "ss\n\t" "incl npx_intrs_while_probing\n\t" "pushl %eax\n\t" "movb $0x20,%al # EOI (asm in strings loses cpp features)\n\t" "outb %al,$0xa0 # IO_ICU2\n\t" "outb %al,$0x20 # IO_ICU1\n\t" "movb $0,%al\n\t" "outb %al,$0xf0 # clear BUSY# latch\n\t" "popl %eax\n\t" "iret\n\t"); void probetrap(void); asm (".text\n\t" "probetrap:\n\t" "ss\n\t" "incl npx_traps_while_probing\n\t" "fnclex\n\t" "iret\n\t"); static inline int npxprobe1(struct isa_attach_args *ia) { int control; int status; ia->ia_iosize = 16; ia->ia_msize = 0; /* * 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) */ /* * 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) { /* * 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(); delay(1); if (npx_traps_while_probing != 0) { /* * Good, exception 16 works. */ npx_type = NPX_EXCEPTION; ia->ia_irq = IRQUNK; /* zap the interrupt */ } else if (npx_intrs_while_probing != 0) { /* * Bad, we are stuck with IRQ13. */ npx_type = NPX_INTERRUPT; } else { /* * Worse, even IRQ13 is broken. */ npx_type = NPX_BROKEN; ia->ia_irq = IRQUNK; } return 1; } } /* * Probe failed. There is no usable FPU. */ npx_type = NPX_NONE; return 0; } /* * 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. */ int npxprobe(struct device *parent, void *match, void *aux) { struct isa_attach_args *ia = aux; int irq; int result; u_long s; unsigned save_imen; struct gate_descriptor save_idt_npxintr; struct gate_descriptor save_idt_npxtrap; if (cpu_feature & CPUID_FPU) { npx_type = NPX_CPUID; ia->ia_irq = IRQUNK; /* Don't want the interrupt vector */ ia->ia_iosize = 16; ia->ia_msize = 0; return 1; } /* * 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. */ irq = NRSVIDT + ia->ia_irq; s = intr_disable(); save_idt_npxintr = idt[irq]; save_idt_npxtrap = idt[16]; setgate(&idt[irq], probeintr, 0, SDT_SYS386IGT, SEL_KPL, GICODE_SEL); setgate(&idt[16], probetrap, 0, SDT_SYS386TGT, SEL_KPL, GCODE_SEL); save_imen = imen; imen = ~((1 << IRQ_SLAVE) | (1 << ia->ia_irq)); SET_ICUS(); /* * 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 */ delay(1000); outb(0xf0, 0); /* clear BUSY# latch */ /* * We set CR0 in locore to trap all ESC and WAIT instructions. * We have to turn off the CR0_EM bit temporarily while probing. */ lcr0(rcr0() & ~(CR0_EM|CR0_TS)); intr_restore(s); result = npxprobe1(ia); s = intr_disable(); lcr0(rcr0() | (CR0_EM|CR0_TS)); imen = save_imen; SET_ICUS(); idt[irq] = save_idt_npxintr; idt[16] = save_idt_npxtrap; intr_restore(s); return (result); } int npx586bug1(int, int); asm (".text\n\t" "npx586bug1:\n\t" "fildl 4(%esp) # x\n\t" "fildl 8(%esp) # y\n\t" "fld %st(1)\n\t" "fdiv %st(1),%st # x/y\n\t" "fmulp %st,%st(1) # (x/y)*y\n\t" "fsubrp %st,%st(1) # x-(x/y)*y\n\t" "pushl $0\n\t" "fistpl (%esp)\n\t" "popl %eax\n\t" "ret\n\t"); void npxinit(struct cpu_info *ci) { lcr0(rcr0() & ~(CR0_EM|CR0_TS)); fninit(); if (npx586bug1(4195835, 3145727) != 0) { printf("%s: WARNING: Pentium FDIV bug detected!\n", ci->ci_dev->dv_xname); } if (fpu_mxcsr_mask == 0 && i386_use_fxsave) { struct savexmm xm __attribute__((aligned(16))); bzero(&xm, sizeof(xm)); fxsave(&xm); if (xm.sv_env.en_mxcsr_mask) fpu_mxcsr_mask = xm.sv_env.en_mxcsr_mask; else fpu_mxcsr_mask = __INITIAL_MXCSR_MASK__; } lcr0(rcr0() | (CR0_TS)); } /* * Attach routine - announce which it is, and wire into system */ void npxattach(struct device *parent, struct device *self, void *aux) { struct npx_softc *sc = (void *)self; struct isa_attach_args *ia = aux; switch (npx_type) { case NPX_INTERRUPT: printf("\n"); lcr0(rcr0() & ~CR0_NE); sc->sc_ih = isa_intr_establish(ia->ia_ic, ia->ia_irq, IST_EDGE, IPL_NONE, npxintr, 0, sc->sc_dev.dv_xname); break; case NPX_EXCEPTION: printf(": using exception 16\n"); break; case NPX_CPUID: printf(": reported by CPUID; using exception 16\n"); npx_type = NPX_EXCEPTION; break; case NPX_BROKEN: printf(": error reporting broken; not using\n"); npx_type = NPX_NONE; return; case NPX_NONE: return; } npxinit(&cpu_info_primary); if (i386_use_fxsave) npxdna_func = npxdna_xmm; else npxdna_func = npxdna_s87; } /* * 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. */ int npxintr(void *arg) { struct cpu_info *ci = curcpu(); struct proc *p = ci->ci_fpcurproc; union savefpu *addr; struct intrframe *frame = arg; int code; union sigval sv; uvmexp.traps++; IPRINTF(("%s: fp intr\n", ci->ci_dev->dv_xname)); if (p == NULL || npx_type == NPX_NONE) { /* XXX no %p in stand/printf.c. Cast to quiet gcc -Wall. */ printf("npxintr: p = %lx, curproc = %lx, npx_type = %d\n", (u_long) p, (u_long) curproc, npx_type); panic("npxintr from nowhere"); } /* * Clear the interrupt latch. */ outb(0xf0, 0); /* * If we're saving, ignore the interrupt. The FPU will happily * generate another one when we restore the state later. */ if (ci->ci_fpsaving) return (1); #ifdef DIAGNOSTIC /* * At this point, fpcurproc should be curproc. If it wasn't, the TS * bit should be set, and we should have gotten a DNA exception. */ if (p != curproc) panic("npxintr: wrong process"); #endif /* * Find the address of fpcurproc's saved FPU state. (Given the * invariant above, this is always the one in curpcb.) */ addr = &p->p_addr->u_pcb.pcb_savefpu; /* * Save state. This does an implied fninit. It had better not halt * the cpu or we'll hang. */ fpu_save(addr); fwait(); /* * Restore control word (was clobbered by fpu_save). */ if (i386_use_fxsave) { fldcw(&addr->sv_xmm.sv_env.en_cw); /* * FNINIT doesn't affect MXCSR or the XMM registers; * no need to re-load MXCSR here. */ } else fldcw(&addr->sv_87.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. */ if (i386_use_fxsave) { addr->sv_xmm.sv_ex_sw = addr->sv_xmm.sv_env.en_sw; addr->sv_xmm.sv_ex_tw = addr->sv_xmm.sv_env.en_tw; } else { addr->sv_87.sv_ex_sw = addr->sv_87.sv_env.en_sw; addr->sv_87.sv_ex_tw = addr->sv_87.sv_env.en_tw; } /* * Pass exception to process. If it's the current process, try to do * it immediately. */ if (p == curproc && USERMODE(frame->if_cs, frame->if_eflags)) { /* * 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). */ p->p_md.md_regs = (struct trapframe *)&frame->if_fs; /* * Encode the appropriate code for detailed information on * this exception. */ if (i386_use_fxsave) code = x86fpflags_to_siginfo(addr->sv_xmm.sv_ex_sw); else code = x86fpflags_to_siginfo(addr->sv_87.sv_ex_sw); sv.sival_int = frame->if_eip; trapsignal(p, SIGFPE, T_ARITHTRAP, code, sv); } 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. */ KERNEL_LOCK(); psignal(p, SIGFPE); KERNEL_UNLOCK(); } return (1); } void npxtrap(struct trapframe *frame) { struct proc *p = curcpu()->ci_fpcurproc; union savefpu *addr = &p->p_addr->u_pcb.pcb_savefpu; u_int32_t mxcsr, statbits; int code; union sigval sv; #ifdef DIAGNOSTIC /* * At this point, fpcurproc should be curproc. If it wasn't, the TS * bit should be set, and we should have gotten a DNA exception. */ if (p != curproc) panic("npxtrap: wrong process"); #endif fxsave(&addr->sv_xmm); mxcsr = addr->sv_xmm.sv_env.en_mxcsr; statbits = mxcsr; mxcsr &= ~0x3f; ldmxcsr(&mxcsr); addr->sv_xmm.sv_ex_sw = addr->sv_xmm.sv_env.en_sw; addr->sv_xmm.sv_ex_tw = addr->sv_xmm.sv_env.en_tw; code = x86fpflags_to_siginfo(statbits); sv.sival_int = frame->tf_eip; trapsignal(p, SIGFPE, frame->tf_err, code, sv); } static int x86fpflags_to_siginfo(u_int32_t flags) { int i; static int x86fp_siginfo_table[] = { FPE_FLTINV, /* bit 0 - invalid operation */ FPE_FLTRES, /* bit 1 - denormal operand */ FPE_FLTDIV, /* bit 2 - divide by zero */ FPE_FLTOVF, /* bit 3 - fp overflow */ FPE_FLTUND, /* bit 4 - fp underflow */ FPE_FLTRES, /* bit 5 - fp precision */ FPE_FLTINV, /* bit 6 - stack fault */ }; for (i=0;i < sizeof(x86fp_siginfo_table)/sizeof(int); i++) { if (flags & (1 << i)) return (x86fp_siginfo_table[i]); } /* punt if flags not set */ return (FPE_FLTINV); } /* * Implement device not available (DNA) exception * * If we were the last process to use the FPU, we can simply return. * Otherwise, we save the previous state, if necessary, and restore our last * saved state. */ int npxdna_xmm(struct cpu_info *ci) { union savefpu *sfp; struct proc *p; int s; if (ci->ci_fpsaving) { printf("recursive npx trap; cr0=%x\n", rcr0()); return (0); } s = splipi(); /* lock out IPI's while we clean house.. */ #ifdef MULTIPROCESSOR p = ci->ci_curproc; #else p = curproc; #endif IPRINTF(("%s: dna for %lx%s\n", ci->ci_dev->dv_xname, (u_long)p, (p->p_md.md_flags & MDP_USEDFPU) ? " (used fpu)" : "")); /* * XXX should have a fast-path here when no save/restore is necessary */ /* * Initialize the FPU state to clear any exceptions. If someone else * was using the FPU, save their state (which does an implicit * initialization). */ if (ci->ci_fpcurproc != NULL) { IPRINTF(("%s: fp save %lx\n", ci->ci_dev->dv_xname, (u_long)ci->ci_fpcurproc)); npxsave_cpu(ci, ci->ci_fpcurproc != &proc0); } else { clts(); IPRINTF(("%s: fp init\n", ci->ci_dev->dv_xname)); fninit(); fwait(); stts(); } splx(s); IPRINTF(("%s: done saving\n", ci->ci_dev->dv_xname)); KDASSERT(ci->ci_fpcurproc == NULL); #ifndef MULTIPROCESSOR KDASSERT(p->p_addr->u_pcb.pcb_fpcpu == NULL); #else if (p->p_addr->u_pcb.pcb_fpcpu != NULL) npxsave_proc(p, 1); #endif p->p_addr->u_pcb.pcb_cr0 &= ~CR0_TS; clts(); s = splipi(); ci->ci_fpcurproc = p; p->p_addr->u_pcb.pcb_fpcpu = ci; splx(s); uvmexp.fpswtch++; sfp = &p->p_addr->u_pcb.pcb_savefpu; if ((p->p_md.md_flags & MDP_USEDFPU) == 0) { bzero(&sfp->sv_xmm, sizeof(sfp->sv_xmm)); sfp->sv_xmm.sv_env.en_cw = __INITIAL_NPXCW__; sfp->sv_xmm.sv_env.en_mxcsr = __INITIAL_MXCSR__; fxrstor(&sfp->sv_xmm); p->p_md.md_flags |= MDP_USEDFPU; } else { static double zero = 0.0; /* * amd fpu does not restore fip, fdp, fop on fxrstor * thus leaking other process's execution history. */ fnclex(); __asm volatile("ffree %%st(7)\n\tfldl %0" : : "m" (zero)); fxrstor(&sfp->sv_xmm); } return (1); } int npxdna_s87(struct cpu_info *ci) { union savefpu *sfp; struct proc *p; int s; KDASSERT(i386_use_fxsave == 0); if (ci->ci_fpsaving) { printf("recursive npx trap; cr0=%x\n", rcr0()); return (0); } s = splipi(); /* lock out IPI's while we clean house.. */ #ifdef MULTIPROCESSOR p = ci->ci_curproc; #else p = curproc; #endif IPRINTF(("%s: dna for %lx%s\n", ci->ci_dev->dv_xname, (u_long)p, (p->p_md.md_flags & MDP_USEDFPU) ? " (used fpu)" : "")); /* * If someone else was using our FPU, save their state (which does an * implicit initialization); otherwise, initialize the FPU state to * clear any exceptions. */ if (ci->ci_fpcurproc != NULL) { IPRINTF(("%s: fp save %lx\n", ci->ci_dev->dv_xname, (u_long)ci->ci_fpcurproc)); npxsave_cpu(ci, ci->ci_fpcurproc != &proc0); } else { clts(); IPRINTF(("%s: fp init\n", ci->ci_dev->dv_xname)); fninit(); fwait(); stts(); } splx(s); IPRINTF(("%s: done saving\n", ci->ci_dev->dv_xname)); KDASSERT(ci->ci_fpcurproc == NULL); #ifndef MULTIPROCESSOR KDASSERT(p->p_addr->u_pcb.pcb_fpcpu == NULL); #else if (p->p_addr->u_pcb.pcb_fpcpu != NULL) npxsave_proc(p, 1); #endif p->p_addr->u_pcb.pcb_cr0 &= ~CR0_TS; clts(); s = splipi(); ci->ci_fpcurproc = p; p->p_addr->u_pcb.pcb_fpcpu = ci; splx(s); uvmexp.fpswtch++; sfp = &p->p_addr->u_pcb.pcb_savefpu; if ((p->p_md.md_flags & MDP_USEDFPU) == 0) { bzero(&sfp->sv_87, sizeof(sfp->sv_87)); sfp->sv_87.sv_env.en_cw = __INITIAL_NPXCW__; sfp->sv_87.sv_env.en_tw = 0xffff; frstor(&sfp->sv_87); p->p_md.md_flags |= MDP_USEDFPU; } else { /* * 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(&sfp->sv_87); } return (1); } /* * The FNSAVE instruction clears the FPU state. Rather than reloading the FPU * immediately, we clear fpcurproc and turn on CR0_TS to force a DNA and a * reload of the FPU state the next time we try to use it. This routine * is only called when forking, core dumping, or debugging, or swapping, * so the lazy reload at worst forces us to trap once per fork(), and at best * saves us a reload once per fork(). */ void npxsave_cpu(struct cpu_info *ci, int save) { struct proc *p; int s; KDASSERT(ci == curcpu()); p = ci->ci_fpcurproc; if (p == NULL) return; IPRINTF(("%s: fp cpu %s %lx\n", ci->ci_dev->dv_xname, save ? "save" : "flush", (u_long)p)); if (save) { #ifdef DIAGNOSTIC if (ci->ci_fpsaving != 0) panic("npxsave_cpu: recursive save!"); #endif /* * Set ci->ci_fpsaving, so that any pending exception will be * thrown away. (It will be caught again if/when the FPU * state is restored.) * * XXX on i386 and earlier, this routine should always be * called at spl0; if it might called with the NPX interrupt * masked, it would be necessary to forcibly unmask the NPX * interrupt so that it could succeed. * XXX this is irrelevant on 486 and above (systems * which report FP failures via traps rather than irq13). * XXX punting for now.. */ clts(); ci->ci_fpsaving = 1; fpu_save(&p->p_addr->u_pcb.pcb_savefpu); ci->ci_fpsaving = 0; /* It is unclear if this is needed. */ fwait(); } /* * We set the TS bit in the saved CR0 for this process, so that it * will get a DNA exception on any FPU instruction and force a reload. */ stts(); p->p_addr->u_pcb.pcb_cr0 |= CR0_TS; s = splipi(); p->p_addr->u_pcb.pcb_fpcpu = NULL; ci->ci_fpcurproc = NULL; splx(s); } /* * Save p's FPU state, which may be on this processor or another processor. */ void npxsave_proc(struct proc *p, int save) { struct cpu_info *ci = curcpu(); struct cpu_info *oci; KDASSERT(p->p_addr != NULL); oci = p->p_addr->u_pcb.pcb_fpcpu; if (oci == NULL) return; IPRINTF(("%s: fp proc %s %lx\n", ci->ci_dev->dv_xname, save ? "save" : "flush", (u_long)p)); #if defined(MULTIPROCESSOR) if (oci == ci) { int s = splipi(); npxsave_cpu(ci, save); splx(s); } else { IPRINTF(("%s: fp ipi to %s %s %lx\n", ci->ci_dev->dv_xname, oci->ci_dev->dv_xname, save ? "save" : "flush", (u_long)p)); oci->ci_fpsaveproc = p; i386_send_ipi(oci, save ? I386_IPI_SYNCH_FPU : I386_IPI_FLUSH_FPU); while (p->p_addr->u_pcb.pcb_fpcpu != NULL) CPU_BUSY_CYCLE(); } #else KASSERT(ci->ci_fpcurproc == p); npxsave_cpu(ci, save); #endif } void fpu_kernel_enter(void) { struct cpu_info *ci = curcpu(); uint32_t cw; int s; /* * Fast path. If the kernel was using the FPU before, there * is no work to do besides clearing TS. */ if (ci->ci_fpcurproc == &proc0) { clts(); return; } s = splipi(); if (ci->ci_fpcurproc != NULL) { npxsave_cpu(ci, 1); uvmexp.fpswtch++; } /* Claim the FPU */ ci->ci_fpcurproc = &proc0; splx(s); /* Disable DNA exceptions */ clts(); /* Initialize the FPU */ fninit(); cw = __INITIAL_NPXCW__; fldcw(&cw); if (i386_has_sse || i386_has_sse2) { cw = __INITIAL_MXCSR__; ldmxcsr(&cw); } } void fpu_kernel_exit(void) { /* Enable DNA exceptions */ stts(); }