FreeBSD/Linux Kernel Cross Reference
sys/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.
     * 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.
     *
     *      from: @(#)npx.c 7.2 (Berkeley) 5/12/91
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/6.0/sys/i386/isa/npx.c 157863 2006-04-19 07:03:14Z cperciva $");
    
    #include "opt_cpu.h"
    #include "opt_isa.h"
    #include "opt_npx.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/mutex.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/smp.h>
    #include <sys/sysctl.h>
    #include <machine/bus.h>
    #include <sys/rman.h>
    #ifdef NPX_DEBUG
    #include <sys/syslog.h>
    #endif
    #include <sys/signalvar.h>
    
    #include <machine/asmacros.h>
    #include <machine/cputypes.h>
    #include <machine/frame.h>
    #include <machine/md_var.h>
    #include <machine/pcb.h>
    #include <machine/psl.h>
    #include <machine/clock.h>
    #include <machine/resource.h>
    #include <machine/specialreg.h>
    #include <machine/segments.h>
    #include <machine/ucontext.h>
    
    #include <machine/intr_machdep.h>
    #ifdef DEV_ISA
    #include <isa/isavar.h>
    #endif
    
    #if !defined(CPU_DISABLE_SSE) && defined(I686_CPU)
    #define CPU_ENABLE_SSE
    #endif
    
    /*
     * 387 and 287 Numeric Coprocessor Extension (NPX) Driver.
     */
    
    /* Configuration flags. */
    #define NPX_DISABLE_I586_OPTIMIZED_BCOPY        (1 << 0)
    #define NPX_DISABLE_I586_OPTIMIZED_BZERO        (1 << 1)
    #define NPX_DISABLE_I586_OPTIMIZED_COPYIO       (1 << 2)
    
    #if defined(__GNUCLIKE_ASM) && !defined(lint)
    
    #define fldcw(addr)             __asm("fldcw %0" : : "m" (*(addr)))
    #define fnclex()                __asm("fnclex")
    #define fninit()                __asm("fninit")
    #define fnsave(addr)            __asm __volatile("fnsave %0" : "=m" (*(addr)))
    #define fnstcw(addr)            __asm __volatile("fnstcw %0" : "=m" (*(addr)))
    #define fnstsw(addr)            __asm __volatile("fnstsw %0" : "=m" (*(addr)))
    #define fp_divide_by_0()        __asm("fldz; fld1; fdiv %st,%st(1); fnop")
    #define frstor(addr)            __asm("frstor %0" : : "m" (*(addr)))
    #ifdef CPU_ENABLE_SSE
   #define fxrstor(addr)           __asm("fxrstor %0" : : "m" (*(addr)))
   #define fxsave(addr)            __asm __volatile("fxsave %0" : "=m" (*(addr)))
   #define ldmxcsr(__csr)          __asm __volatile("ldmxcsr %0" : : "m" (__csr))
   #endif
   #define start_emulating()       __asm("smsw %%ax; orb %0,%%al; lmsw %%ax" \
                                         : : "n" (CR0_TS) : "ax")
   #define stop_emulating()        __asm("clts")
   
   #else   /* !(__GNUCLIKE_ASM && !lint) */
   
   void    fldcw(caddr_t addr);
   void    fnclex(void);
   void    fninit(void);
   void    fnsave(caddr_t addr);
   void    fnstcw(caddr_t addr);
   void    fnstsw(caddr_t addr);
   void    fp_divide_by_0(void);
   void    frstor(caddr_t addr);
   #ifdef CPU_ENABLE_SSE
   void    fxsave(caddr_t addr);
   void    fxrstor(caddr_t addr);
   #endif
   void    start_emulating(void);
   void    stop_emulating(void);
   
   #endif  /* __GNUCLIKE_ASM && !lint */
   
   #ifdef CPU_ENABLE_SSE
   #define GET_FPU_CW(thread) \
           (cpu_fxsr ? \
                   (thread)->td_pcb->pcb_save.sv_xmm.sv_env.en_cw : \
                   (thread)->td_pcb->pcb_save.sv_87.sv_env.en_cw)
   #define GET_FPU_SW(thread) \
           (cpu_fxsr ? \
                   (thread)->td_pcb->pcb_save.sv_xmm.sv_env.en_sw : \
                   (thread)->td_pcb->pcb_save.sv_87.sv_env.en_sw)
   #else /* CPU_ENABLE_SSE */
   #define GET_FPU_CW(thread) \
           (thread->td_pcb->pcb_save.sv_87.sv_env.en_cw)
   #define GET_FPU_SW(thread) \
           (thread->td_pcb->pcb_save.sv_87.sv_env.en_sw)
   #endif /* CPU_ENABLE_SSE */
   
   typedef u_char bool_t;
   
   #ifdef CPU_ENABLE_SSE
   static  void    fpu_clean_state(void);
   #endif
   
   static  void    fpusave(union savefpu *);
   static  void    fpurstor(union savefpu *);
   static  int     npx_attach(device_t dev);
   static  void    npx_identify(driver_t *driver, device_t parent);
   static  void    npx_intr(void *);
   static  int     npx_probe(device_t dev);
   #ifdef I586_CPU_XXX
   static  long    timezero(const char *funcname,
                       void (*func)(void *buf, size_t len));
   #endif /* I586_CPU */
   
   int     hw_float;               /* XXX currently just alias for npx_exists */
   
   SYSCTL_INT(_hw,HW_FLOATINGPT, floatingpoint,
           CTLFLAG_RD, &hw_float, 0, 
           "Floatingpoint instructions executed in hardware");
   
   static  volatile u_int          npx_intrs_while_probing;
   static  volatile u_int          npx_traps_while_probing;
   
   static  union savefpu           npx_cleanstate;
   static  bool_t                  npx_cleanstate_ready;
   static  bool_t                  npx_ex16;
   static  bool_t                  npx_exists;
   static  bool_t                  npx_irq13;
   
   alias_for_inthand_t probetrap;
   __asm("                                                         \n\
           .text                                                   \n\
           .p2align 2,0x90                                         \n\
           .type   " __XSTRING(CNAME(probetrap)) ",@function       \n\
   " __XSTRING(CNAME(probetrap)) ":                                \n\
           ss                                                      \n\
           incl    " __XSTRING(CNAME(npx_traps_while_probing)) "   \n\
           fnclex                                                  \n\
           iret                                                    \n\
   ");
   
   /*
    * Identify routine.  Create a connection point on our parent for probing.
    */
   static void
   npx_identify(driver, parent)
           driver_t *driver;
           device_t parent;
   {
           device_t child;
   
           child = BUS_ADD_CHILD(parent, 0, "npx", 0);
           if (child == NULL)
                   panic("npx_identify");
   }
   
   /*
    * Do minimal handling of npx interrupts to convert them to traps.
    */
   static void
   npx_intr(dummy)
           void *dummy;
   {
           struct thread *td;
   
           npx_intrs_while_probing++;
   
           /*
            * The BUSY# latch must be cleared in all cases so that the next
            * unmasked npx exception causes an interrupt.
            */
           outb(IO_NPX, 0);
   
           /*
            * fpcurthread is normally non-null here.  In that case, schedule an
            * AST to finish the exception handling in the correct context
            * (this interrupt may occur after the thread has entered the
            * kernel via a syscall or an interrupt).  Otherwise, the npx
            * state of the thread that caused this interrupt must have been
            * pushed to the thread's pcb, and clearing of the busy latch
            * above has finished the (essentially null) handling of this
            * interrupt.  Control will eventually return to the instruction
            * that caused it and it will repeat.  We will eventually (usually
            * soon) win the race to handle the interrupt properly.
            */
           td = PCPU_GET(fpcurthread);
           if (td != NULL) {
                   td->td_pcb->pcb_flags |= PCB_NPXTRAP;
                   mtx_lock_spin(&sched_lock);
                   td->td_flags |= TDF_ASTPENDING;
                   mtx_unlock_spin(&sched_lock);
           }
   }
   
   /*
    * 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 0 if device exists.
    */
   static int
   npx_probe(dev)
           device_t dev;
   {
           struct gate_descriptor save_idt_npxtrap;
           struct resource *ioport_res, *irq_res;
           void *irq_cookie;
           int ioport_rid, irq_num, irq_rid;
           u_short control;
           u_short status;
   
           save_idt_npxtrap = idt[IDT_MF];
           setidt(IDT_MF, probetrap, SDT_SYS386TGT, SEL_KPL,
               GSEL(GCODE_SEL, SEL_KPL));
           ioport_rid = 0;
           ioport_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &ioport_rid,
               IO_NPX, IO_NPX + IO_NPXSIZE - 1, IO_NPXSIZE, RF_ACTIVE);
           if (ioport_res == NULL)
                   panic("npx: can't get ports");
           if (resource_int_value("npx", 0, "irq", &irq_num) != 0)
                   irq_num = IRQ_NPX;
           irq_rid = 0;
           irq_res = bus_alloc_resource(dev, SYS_RES_IRQ, &irq_rid, irq_num,
               irq_num, 1, RF_ACTIVE);
           if (irq_res == NULL)
                   panic("npx: can't get IRQ");
           if (bus_setup_intr(dev, irq_res, INTR_TYPE_MISC | INTR_FAST, npx_intr,
               NULL, &irq_cookie) != 0)
                   panic("npx: can't create intr");
   
           /*
            * Partially reset the coprocessor, if any.  Some BIOS's don't reset
            * it after a warm boot.
            */
           npx_full_reset();
           outb(IO_NPX, 0);
   
           /*
            * 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 npx_intr() 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();
   
           device_set_desc(dev, "math processor");
   
           /*
            * Don't use fwait here because it might hang.
            * Don't use fnop here because it usually hangs if there is no FPU.
            */
           DELAY(1000);            /* wait for any IRQ13 */
   #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) {
                           hw_float = 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);
   #ifdef FPU_ERROR_BROKEN
                           /*
                            * FPU error signal doesn't work on some CPU
                            * accelerator board.
                            */
                           npx_ex16 = 1;
                           return (0);
   #endif
                           npx_traps_while_probing = npx_intrs_while_probing = 0;
                           fp_divide_by_0();
                           DELAY(1000);    /* wait for any IRQ13 */
                           if (npx_traps_while_probing != 0) {
                                   /*
                                    * Good, exception 16 works.
                                    */
                                   npx_ex16 = 1;
                                   goto no_irq13;
                           }
                           if (npx_intrs_while_probing != 0) {
                                   /*
                                    * Bad, we are stuck with IRQ13.
                                    */
                                   npx_irq13 = 1;
                                   idt[IDT_MF] = save_idt_npxtrap;
   #ifdef SMP
                                   if (mp_ncpus > 1)
                                           panic("npx0 cannot use IRQ 13 on an SMP system");
   #endif
                                   return (0);
                           }
                           /*
                            * 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.
            */
   #ifdef SMP
           if (mp_ncpus > 1)
                   panic("npx0 cannot be emulated on an SMP system");
   #endif
           /* FALLTHROUGH */
   no_irq13:
           idt[IDT_MF] = save_idt_npxtrap;
           bus_teardown_intr(dev, irq_res, irq_cookie);
           bus_release_resource(dev, SYS_RES_IRQ, irq_rid, irq_res);
           bus_release_resource(dev, SYS_RES_IOPORT, ioport_rid, ioport_res);
           return (0);
   }
   
   /*
    * Attach routine - announce which it is, and wire into system
    */
   static int
   npx_attach(dev)
           device_t dev;
   {
           int flags;
           register_t s;
   
           flags = device_get_flags(dev);
   
           if (npx_irq13)
                   device_printf(dev, "IRQ 13 interface\n");
           else if (npx_ex16)
                   device_printf(dev, "INT 16 interface\n");
           else
                   device_printf(dev, "WARNING: no FPU!\n");
   
           npxinit(__INITIAL_NPXCW__);
   
           if (npx_cleanstate_ready == 0) {
                   s = intr_disable();
                   stop_emulating();
                   fpusave(&npx_cleanstate);
                   start_emulating();
                   npx_cleanstate_ready = 1;
                   intr_restore(s);
           }
   #ifdef I586_CPU_XXX
           if (cpu_class == CPUCLASS_586 && npx_ex16 && npx_exists &&
               timezero("i586_bzero()", i586_bzero) <
               timezero("bzero()", bzero) * 4 / 5) {
                   if (!(flags & NPX_DISABLE_I586_OPTIMIZED_BCOPY))
                           bcopy_vector = i586_bcopy;
                   if (!(flags & NPX_DISABLE_I586_OPTIMIZED_BZERO))
                           bzero_vector = i586_bzero;
                   if (!(flags & NPX_DISABLE_I586_OPTIMIZED_COPYIO)) {
                           copyin_vector = i586_copyin;
                           copyout_vector = i586_copyout;
                   }
           }
   #endif
   
           return (0);             /* XXX unused */
   }
   
   /*
    * Initialize floating point unit.
    */
   void
   npxinit(control)
           u_short control;
   {
           static union savefpu dummy;
           register_t savecrit;
   
           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.  npxsave() initializes
            * the fpu and sets fpcurthread = NULL as important side effects.
            */
           savecrit = intr_disable();
           npxsave(&dummy);
           stop_emulating();
   #ifdef CPU_ENABLE_SSE
           /* XXX npxsave() doesn't actually initialize the fpu in the SSE case. */
           if (cpu_fxsr)
                   fninit();
   #endif
           fldcw(&control);
           start_emulating();
           intr_restore(savecrit);
   }
   
   /*
    * Free coprocessor (if we have it).
    */
   void
   npxexit(td)
           struct thread *td;
   {
           register_t savecrit;
   
           savecrit = intr_disable();
           if (curthread == PCPU_GET(fpcurthread))
                   npxsave(&PCPU_GET(curpcb)->pcb_save);
           intr_restore(savecrit);
   #ifdef NPX_DEBUG
           if (npx_exists) {
                   u_int   masked_exceptions;
   
                   masked_exceptions = GET_FPU_CW(td) & GET_FPU_SW(td) & 0x7f;
                   /*
                    * Log exceptions that would have trapped with the old
                    * control word (overflow, divide by 0, and invalid operand).
                    */
                   if (masked_exceptions & 0x0d)
                           log(LOG_ERR,
           "pid %d (%s) exited with masked floating point exceptions 0x%02x\n",
                               td->td_proc->p_pid, td->td_proc->p_comm,
                               masked_exceptions);
           }
   #endif
   }
   
   int
   npxformat()
   {
   
           if (!npx_exists)
                   return (_MC_FPFMT_NODEV);
   #ifdef  CPU_ENABLE_SSE
           if (cpu_fxsr)
                   return (_MC_FPFMT_XMM);
   #endif
           return (_MC_FPFMT_387);
   }
   
   /* 
    * The following mechanism is used to ensure that the FPE_... value
    * that is passed as a trapcode to the signal handler of the user
    * process does not have more than one bit set.
    * 
    * Multiple bits may be set if the user process modifies the control
    * word while a status word bit is already set.  While this is a sign
    * of bad coding, we have no choise than to narrow them down to one
    * bit, since we must not send a trapcode that is not exactly one of
    * the FPE_ macros.
    *
    * The mechanism has a static table with 127 entries.  Each combination
    * of the 7 FPU status word exception bits directly translates to a
    * position in this table, where a single FPE_... value is stored.
    * This FPE_... value stored there is considered the "most important"
    * of the exception bits and will be sent as the signal code.  The
    * precedence of the bits is based upon Intel Document "Numerical
    * Applications", Chapter "Special Computational Situations".
    *
    * The macro to choose one of these values does these steps: 1) Throw
    * away status word bits that cannot be masked.  2) Throw away the bits
    * currently masked in the control word, assuming the user isn't
    * interested in them anymore.  3) Reinsert status word bit 7 (stack
    * fault) if it is set, which cannot be masked but must be presered.
    * 4) Use the remaining bits to point into the trapcode table.
    *
    * The 6 maskable bits in order of their preference, as stated in the
    * above referenced Intel manual:
    * 1  Invalid operation (FP_X_INV)
    * 1a   Stack underflow
    * 1b   Stack overflow
    * 1c   Operand of unsupported format
    * 1d   SNaN operand.
    * 2  QNaN operand (not an exception, irrelavant here)
    * 3  Any other invalid-operation not mentioned above or zero divide
    *      (FP_X_INV, FP_X_DZ)
    * 4  Denormal operand (FP_X_DNML)
    * 5  Numeric over/underflow (FP_X_OFL, FP_X_UFL)
    * 6  Inexact result (FP_X_IMP) 
    */
   static char fpetable[128] = {
           0,
           FPE_FLTINV,     /*  1 - INV */
           FPE_FLTUND,     /*  2 - DNML */
           FPE_FLTINV,     /*  3 - INV | DNML */
           FPE_FLTDIV,     /*  4 - DZ */
           FPE_FLTINV,     /*  5 - INV | DZ */
           FPE_FLTDIV,     /*  6 - DNML | DZ */
           FPE_FLTINV,     /*  7 - INV | DNML | DZ */
           FPE_FLTOVF,     /*  8 - OFL */
           FPE_FLTINV,     /*  9 - INV | OFL */
           FPE_FLTUND,     /*  A - DNML | OFL */
           FPE_FLTINV,     /*  B - INV | DNML | OFL */
           FPE_FLTDIV,     /*  C - DZ | OFL */
           FPE_FLTINV,     /*  D - INV | DZ | OFL */
           FPE_FLTDIV,     /*  E - DNML | DZ | OFL */
           FPE_FLTINV,     /*  F - INV | DNML | DZ | OFL */
           FPE_FLTUND,     /* 10 - UFL */
           FPE_FLTINV,     /* 11 - INV | UFL */
           FPE_FLTUND,     /* 12 - DNML | UFL */
           FPE_FLTINV,     /* 13 - INV | DNML | UFL */
           FPE_FLTDIV,     /* 14 - DZ | UFL */
           FPE_FLTINV,     /* 15 - INV | DZ | UFL */
           FPE_FLTDIV,     /* 16 - DNML | DZ | UFL */
           FPE_FLTINV,     /* 17 - INV | DNML | DZ | UFL */
           FPE_FLTOVF,     /* 18 - OFL | UFL */
           FPE_FLTINV,     /* 19 - INV | OFL | UFL */
           FPE_FLTUND,     /* 1A - DNML | OFL | UFL */
           FPE_FLTINV,     /* 1B - INV | DNML | OFL | UFL */
           FPE_FLTDIV,     /* 1C - DZ | OFL | UFL */
           FPE_FLTINV,     /* 1D - INV | DZ | OFL | UFL */
           FPE_FLTDIV,     /* 1E - DNML | DZ | OFL | UFL */
           FPE_FLTINV,     /* 1F - INV | DNML | DZ | OFL | UFL */
           FPE_FLTRES,     /* 20 - IMP */
           FPE_FLTINV,     /* 21 - INV | IMP */
           FPE_FLTUND,     /* 22 - DNML | IMP */
           FPE_FLTINV,     /* 23 - INV | DNML | IMP */
           FPE_FLTDIV,     /* 24 - DZ | IMP */
           FPE_FLTINV,     /* 25 - INV | DZ | IMP */
           FPE_FLTDIV,     /* 26 - DNML | DZ | IMP */
           FPE_FLTINV,     /* 27 - INV | DNML | DZ | IMP */
           FPE_FLTOVF,     /* 28 - OFL | IMP */
           FPE_FLTINV,     /* 29 - INV | OFL | IMP */
           FPE_FLTUND,     /* 2A - DNML | OFL | IMP */
           FPE_FLTINV,     /* 2B - INV | DNML | OFL | IMP */
           FPE_FLTDIV,     /* 2C - DZ | OFL | IMP */
           FPE_FLTINV,     /* 2D - INV | DZ | OFL | IMP */
           FPE_FLTDIV,     /* 2E - DNML | DZ | OFL | IMP */
           FPE_FLTINV,     /* 2F - INV | DNML | DZ | OFL | IMP */
           FPE_FLTUND,     /* 30 - UFL | IMP */
           FPE_FLTINV,     /* 31 - INV | UFL | IMP */
           FPE_FLTUND,     /* 32 - DNML | UFL | IMP */
           FPE_FLTINV,     /* 33 - INV | DNML | UFL | IMP */
           FPE_FLTDIV,     /* 34 - DZ | UFL | IMP */
           FPE_FLTINV,     /* 35 - INV | DZ | UFL | IMP */
           FPE_FLTDIV,     /* 36 - DNML | DZ | UFL | IMP */
           FPE_FLTINV,     /* 37 - INV | DNML | DZ | UFL | IMP */
           FPE_FLTOVF,     /* 38 - OFL | UFL | IMP */
           FPE_FLTINV,     /* 39 - INV | OFL | UFL | IMP */
           FPE_FLTUND,     /* 3A - DNML | OFL | UFL | IMP */
           FPE_FLTINV,     /* 3B - INV | DNML | OFL | UFL | IMP */
           FPE_FLTDIV,     /* 3C - DZ | OFL | UFL | IMP */
           FPE_FLTINV,     /* 3D - INV | DZ | OFL | UFL | IMP */
           FPE_FLTDIV,     /* 3E - DNML | DZ | OFL | UFL | IMP */
           FPE_FLTINV,     /* 3F - INV | DNML | DZ | OFL | UFL | IMP */
           FPE_FLTSUB,     /* 40 - STK */
           FPE_FLTSUB,     /* 41 - INV | STK */
           FPE_FLTUND,     /* 42 - DNML | STK */
           FPE_FLTSUB,     /* 43 - INV | DNML | STK */
           FPE_FLTDIV,     /* 44 - DZ | STK */
           FPE_FLTSUB,     /* 45 - INV | DZ | STK */
           FPE_FLTDIV,     /* 46 - DNML | DZ | STK */
           FPE_FLTSUB,     /* 47 - INV | DNML | DZ | STK */
           FPE_FLTOVF,     /* 48 - OFL | STK */
           FPE_FLTSUB,     /* 49 - INV | OFL | STK */
           FPE_FLTUND,     /* 4A - DNML | OFL | STK */
           FPE_FLTSUB,     /* 4B - INV | DNML | OFL | STK */
           FPE_FLTDIV,     /* 4C - DZ | OFL | STK */
           FPE_FLTSUB,     /* 4D - INV | DZ | OFL | STK */
           FPE_FLTDIV,     /* 4E - DNML | DZ | OFL | STK */
           FPE_FLTSUB,     /* 4F - INV | DNML | DZ | OFL | STK */
           FPE_FLTUND,     /* 50 - UFL | STK */
           FPE_FLTSUB,     /* 51 - INV | UFL | STK */
           FPE_FLTUND,     /* 52 - DNML | UFL | STK */
           FPE_FLTSUB,     /* 53 - INV | DNML | UFL | STK */
           FPE_FLTDIV,     /* 54 - DZ | UFL | STK */
           FPE_FLTSUB,     /* 55 - INV | DZ | UFL | STK */
           FPE_FLTDIV,     /* 56 - DNML | DZ | UFL | STK */
           FPE_FLTSUB,     /* 57 - INV | DNML | DZ | UFL | STK */
           FPE_FLTOVF,     /* 58 - OFL | UFL | STK */
           FPE_FLTSUB,     /* 59 - INV | OFL | UFL | STK */
           FPE_FLTUND,     /* 5A - DNML | OFL | UFL | STK */
           FPE_FLTSUB,     /* 5B - INV | DNML | OFL | UFL | STK */
           FPE_FLTDIV,     /* 5C - DZ | OFL | UFL | STK */
           FPE_FLTSUB,     /* 5D - INV | DZ | OFL | UFL | STK */
           FPE_FLTDIV,     /* 5E - DNML | DZ | OFL | UFL | STK */
           FPE_FLTSUB,     /* 5F - INV | DNML | DZ | OFL | UFL | STK */
           FPE_FLTRES,     /* 60 - IMP | STK */
           FPE_FLTSUB,     /* 61 - INV | IMP | STK */
           FPE_FLTUND,     /* 62 - DNML | IMP | STK */
           FPE_FLTSUB,     /* 63 - INV | DNML | IMP | STK */
           FPE_FLTDIV,     /* 64 - DZ | IMP | STK */
           FPE_FLTSUB,     /* 65 - INV | DZ | IMP | STK */
           FPE_FLTDIV,     /* 66 - DNML | DZ | IMP | STK */
           FPE_FLTSUB,     /* 67 - INV | DNML | DZ | IMP | STK */
           FPE_FLTOVF,     /* 68 - OFL | IMP | STK */
           FPE_FLTSUB,     /* 69 - INV | OFL | IMP | STK */
           FPE_FLTUND,     /* 6A - DNML | OFL | IMP | STK */
           FPE_FLTSUB,     /* 6B - INV | DNML | OFL | IMP | STK */
           FPE_FLTDIV,     /* 6C - DZ | OFL | IMP | STK */
           FPE_FLTSUB,     /* 6D - INV | DZ | OFL | IMP | STK */
           FPE_FLTDIV,     /* 6E - DNML | DZ | OFL | IMP | STK */
           FPE_FLTSUB,     /* 6F - INV | DNML | DZ | OFL | IMP | STK */
           FPE_FLTUND,     /* 70 - UFL | IMP | STK */
           FPE_FLTSUB,     /* 71 - INV | UFL | IMP | STK */
           FPE_FLTUND,     /* 72 - DNML | UFL | IMP | STK */
           FPE_FLTSUB,     /* 73 - INV | DNML | UFL | IMP | STK */
           FPE_FLTDIV,     /* 74 - DZ | UFL | IMP | STK */
           FPE_FLTSUB,     /* 75 - INV | DZ | UFL | IMP | STK */
           FPE_FLTDIV,     /* 76 - DNML | DZ | UFL | IMP | STK */
           FPE_FLTSUB,     /* 77 - INV | DNML | DZ | UFL | IMP | STK */
           FPE_FLTOVF,     /* 78 - OFL | UFL | IMP | STK */
           FPE_FLTSUB,     /* 79 - INV | OFL | UFL | IMP | STK */
           FPE_FLTUND,     /* 7A - DNML | OFL | UFL | IMP | STK */
           FPE_FLTSUB,     /* 7B - INV | DNML | OFL | UFL | IMP | STK */
           FPE_FLTDIV,     /* 7C - DZ | OFL | UFL | IMP | STK */
           FPE_FLTSUB,     /* 7D - INV | DZ | OFL | UFL | IMP | STK */
           FPE_FLTDIV,     /* 7E - DNML | DZ | OFL | UFL | IMP | STK */
           FPE_FLTSUB,     /* 7F - INV | DNML | DZ | OFL | UFL | IMP | STK */
   };
   
   /*
    * Preserve the FP status word, clear FP exceptions, then generate a SIGFPE.
    *
    * Clearing exceptions is necessary mainly to avoid IRQ13 bugs.  We now
    * depend on longjmp() restoring a usable state.  Restoring the state
    * or examining it might fail if we didn't clear exceptions.
    *
    * The error code chosen will be one of the FPE_... macros. It will be
    * sent as the second argument to old BSD-style signal handlers and as
    * "siginfo_t->si_code" (second argument) to SA_SIGINFO signal handlers.
    *
    * XXX the FP state is not preserved across signal handlers.  So signal
    * handlers cannot afford to do FP unless they preserve the state or
    * longjmp() out.  Both preserving the state and longjmp()ing may be
    * destroyed by IRQ13 bugs.  Clearing FP exceptions is not an acceptable
    * solution for signals other than SIGFPE.
    */
   int
   npxtrap()
   {
           register_t savecrit;
           u_short control, status;
   
           if (!npx_exists) {
                   printf("npxtrap: fpcurthread = %p, curthread = %p, npx_exists = %d\n",
                          PCPU_GET(fpcurthread), curthread, npx_exists);
                   panic("npxtrap from nowhere");
           }
           savecrit = intr_disable();
   
           /*
            * Interrupt handling (for another interrupt) may have pushed the
            * state to memory.  Fetch the relevant parts of the state from
            * wherever they are.
            */
           if (PCPU_GET(fpcurthread) != curthread) {
                   control = GET_FPU_CW(curthread);
                   status = GET_FPU_SW(curthread);
           } else {
                   fnstcw(&control);
                   fnstsw(&status);
           }
   
           if (PCPU_GET(fpcurthread) == curthread)
                   fnclex();
           intr_restore(savecrit);
           return (fpetable[status & ((~control & 0x3f) | 0x40)]);
   }
   
   /*
    * Implement device not available (DNA) exception
    *
    * It would be better to switch FP context here (if curthread != fpcurthread)
    * and not necessarily for every context switch, but it is too hard to
    * access foreign pcb's.
    */
   
   static int err_count = 0;
   
   int
   npxdna()
   {
           struct pcb *pcb;
           register_t s;
   #ifdef CPU_ENABLE_SSE
           int mxcsr;
   #endif
           u_short control;
   
           if (!npx_exists)
                   return (0);
           if (PCPU_GET(fpcurthread) == curthread) {
                   printf("npxdna: fpcurthread == curthread %d times\n",
                       ++err_count);
                   stop_emulating();
                   return (1);
           }
           if (PCPU_GET(fpcurthread) != NULL) {
                   printf("npxdna: fpcurthread = %p (%d), curthread = %p (%d)\n",
                          PCPU_GET(fpcurthread),
                          PCPU_GET(fpcurthread)->td_proc->p_pid,
                          curthread, curthread->td_proc->p_pid);
                   panic("npxdna");
           }
           s = intr_disable();
           stop_emulating();
           /*
            * Record new context early in case frstor causes an IRQ13.
            */
           PCPU_SET(fpcurthread, curthread);
           pcb = PCPU_GET(curpcb);
   
           if ((pcb->pcb_flags & PCB_NPXINITDONE) == 0) {
                   /*
                    * This is the first time this thread has used the FPU or
                    * the PCB doesn't contain a clean FPU state.  Explicitly
                    * initialize the FPU and load the default control word.
                    */
                   fninit();
                   control = __INITIAL_NPXCW__;
                   fldcw(&control);
   #ifdef CPU_ENABLE_SSE
                   if (cpu_fxsr) {
                           mxcsr = __INITIAL_MXCSR__;
                           ldmxcsr(mxcsr);
                   }
   #endif
                   pcb->pcb_flags |= PCB_NPXINITDONE;
           } 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.
                    */
                   fpurstor(&pcb->pcb_save);
           }
           intr_restore(s);
   
           return (1);
   }
   
   /*
    * Wrapper for fnsave instruction, partly to handle hardware bugs.  When npx
    * exceptions are reported via IRQ13, spurious IRQ13's may be triggered by
    * no-wait npx instructions.  See the Intel application note AP-578 for
    * details.  This doesn't cause any additional complications here.  IRQ13's
    * are inherently asynchronous unless the CPU is frozen to deliver them --
    * one that started in userland may be delivered many instructions later,
    * after the process has entered the kernel.  It may even be delivered after
    * the fnsave here completes.  A spurious IRQ13 for the fnsave is handled in
    * the same way as a very-late-arriving non-spurious IRQ13 from user mode:
    * it is normally ignored at first because we set fpcurthread to NULL; it is
    * normally retriggered in npxdna() after return to user mode.
    *
    * npxsave() must be called with interrupts disabled, so that it clears
    * fpcurthread atomically with saving the state.  We require callers to do the
    * disabling, since most callers need to disable interrupts anyway to call
    * npxsave() atomically with checking fpcurthread.
    *
    * A previous version of npxsave() went to great lengths to excecute fnsave
    * with interrupts enabled in case executing it froze the CPU.  This case
    * can't happen, at least for Intel CPU/NPX's.  Spurious IRQ13's don't imply
    * spurious freezes.
    */
   void
   npxsave(addr)
           union savefpu *addr;
   {
   
           stop_emulating();
           fpusave(addr);
   
           start_emulating();
           PCPU_SET(fpcurthread, NULL);
   }
   
   /*
    * This should be called with interrupts disabled and only when the owning
    * FPU thread is non-null.
    */
   void
   npxdrop()
   {
           struct thread *td;
   
           /*
            * Discard pending exceptions in the !cpu_fxsr case so that unmasked
            * ones don't cause a panic on the next frstor.
            */
   #ifdef CPU_ENABLE_SSE
           if (!cpu_fxsr)
   #endif
                   fnclex();
   
           td = PCPU_GET(fpcurthread);
           PCPU_SET(fpcurthread, NULL);
           td->td_pcb->pcb_flags &= ~PCB_NPXINITDONE;
           start_emulating();
   }
   
   /*
    * Get the state of the FPU without dropping ownership (if possible).
    * It returns the FPU ownership status.
    */
   int
   npxgetregs(td, addr)
           struct thread *td;
           union savefpu *addr;
   {
           register_t s;
   
           if (!npx_exists)
                   return (_MC_FPOWNED_NONE);
   
           if ((td->td_pcb->pcb_flags & PCB_NPXINITDONE) == 0) {
                   if (npx_cleanstate_ready)
                           bcopy(&npx_cleanstate, addr, sizeof(npx_cleanstate));
                   else
                           bzero(addr, sizeof(*addr));
                   return (_MC_FPOWNED_NONE);
           }
           s = intr_disable();
           if (td == PCPU_GET(fpcurthread)) {
                   fpusave(addr);
   #ifdef CPU_ENABLE_SSE
                   if (!cpu_fxsr)
   #endif
                           /*
                            * fnsave initializes the FPU and destroys whatever
                            * context it contains.  Make sure the FPU owner
                            * starts with a clean state next time.
                            */
                           npxdrop();
                   intr_restore(s);
                   return (_MC_FPOWNED_FPU);
           } else {
                   intr_restore(s);
                   bcopy(&td->td_pcb->pcb_save, addr, sizeof(*addr));
                   return (_MC_FPOWNED_PCB);
           }
   }
   
   /*
    * Set the state of the FPU.
    */
   void
   npxsetregs(td, addr)
           struct thread *td;
           union savefpu *addr;
   {
           register_t s;
   
           if (!npx_exists)
                   return;
   
           s = intr_disable();
           if (td == PCPU_GET(fpcurthread)) {
   #ifdef CPU_ENABLE_SSE
                   if (!cpu_fxsr)
   #endif
                           fnclex();       /* As in npxdrop(). */
                   fpurstor(addr);
                   intr_restore(s);
           } else {
                   intr_restore(s);
                   bcopy(addr, &td->td_pcb->pcb_save, sizeof(*addr));
           }
           curthread->td_pcb->pcb_flags |= PCB_NPXINITDONE;
   }
   
   static void
   fpusave(addr)
           union savefpu *addr;
   {
           
   #ifdef CPU_ENABLE_SSE
           if (cpu_fxsr)
                   fxsave(addr);
           else
   #endif
                   fnsave(addr);
   }
   
   #ifdef CPU_ENABLE_SSE
   /*
    * On AuthenticAMD processors, the fxrstor instruction does not restore
    * the x87's stored last instruction pointer, last data pointer, and last
    * opcode values, except in the rare case in which the exception summary
    * (ES) bit in the x87 status word is set to 1.
    *
    * In order to avoid leaking this information across processes, we clean
    * these values by performing a dummy load before executing fxrstor().
    */
   static  double  dummy_variable = 0.0;
   static void
   fpu_clean_state(void)
   {
           u_short status;
   
           /*
            * Clear the ES bit in the x87 status word if it is currently
            * set, in order to avoid causing a fault in the upcoming load.
            */
           fnstsw(&status);
           if (status & 0x80)
                   fnclex();
   
           /*
            * Load the dummy variable into the x87 stack.  This mangles
            * the x87 stack, but we don't care since we're about to call
            * fxrstor() anyway.
            */
           __asm __volatile("ffree %%st(7); fld %0" : : "m" (dummy_variable));
   }
   #endif /* CPU_ENABLE_SSE */
   
   static void
   fpurstor(addr)
           union savefpu *addr;
   {
   
   #ifdef CPU_ENABLE_SSE
          if (cpu_fxsr) {
                  fpu_clean_state();
                  fxrstor(addr);
          } else
  #endif
                  frstor(addr);
  }
  
  #ifdef I586_CPU_XXX
  static long
  timezero(funcname, func)
          const char *funcname;
          void (*func)(void *buf, size_t len);
  
  {
          void *buf;
  #define BUFSIZE         1048576
          long usec;
          struct timeval finish, start;
  
          buf = malloc(BUFSIZE, M_TEMP, M_NOWAIT);
          if (buf == NULL)
                  return (BUFSIZE);
          microtime(&start);
          (*func)(buf, BUFSIZE);
          microtime(&finish);
          usec = 1000000 * (finish.tv_sec - start.tv_sec) +
              finish.tv_usec - start.tv_usec;
          if (usec <= 0)
                  usec = 1;
          if (bootverbose)
                  printf("%s bandwidth = %u kBps\n", funcname,
                      (u_int32_t)(((BUFSIZE >> 10) * 1000000) / usec));
          free(buf, M_TEMP);
          return (usec);
  }
  #endif /* I586_CPU */
  
  static device_method_t npx_methods[] = {
          /* Device interface */
          DEVMETHOD(device_identify,      npx_identify),
          DEVMETHOD(device_probe,         npx_probe),
          DEVMETHOD(device_attach,        npx_attach),
          DEVMETHOD(device_detach,        bus_generic_detach),
          DEVMETHOD(device_shutdown,      bus_generic_shutdown),
          DEVMETHOD(device_suspend,       bus_generic_suspend),
          DEVMETHOD(device_resume,        bus_generic_resume),
          
          { 0, 0 }
  };
  
  static driver_t npx_driver = {
          "npx",
          npx_methods,
          1,                      /* no softc */
  };
  
  static devclass_t npx_devclass;
  
  /*
   * We prefer to attach to the root nexus so that the usual case (exception 16)
   * doesn't describe the processor as being `on isa'.
   */
  DRIVER_MODULE(npx, nexus, npx_driver, npx_devclass, 0, 0);
  
  #ifdef DEV_ISA
  /*
   * This sucks up the legacy ISA support assignments from PNPBIOS/ACPI.
   */
  static struct isa_pnp_id npxisa_ids[] = {
          { 0x040cd041, "Legacy ISA coprocessor support" }, /* PNP0C04 */
          { 0 }
  };
  
  static int
  npxisa_probe(device_t dev)
  {
          int result;
          if ((result = ISA_PNP_PROBE(device_get_parent(dev), dev, npxisa_ids)) <= 0) {
                  device_quiet(dev);
          }
          return(result);
  }
  
  static int
  npxisa_attach(device_t dev)
  {
          return (0);
  }
  
  static device_method_t npxisa_methods[] = {
          /* Device interface */
          DEVMETHOD(device_probe,         npxisa_probe),
          DEVMETHOD(device_attach,        npxisa_attach),
          DEVMETHOD(device_detach,        bus_generic_detach),
          DEVMETHOD(device_shutdown,      bus_generic_shutdown),
          DEVMETHOD(device_suspend,       bus_generic_suspend),
          DEVMETHOD(device_resume,        bus_generic_resume),
          
          { 0, 0 }
  };
  
  static driver_t npxisa_driver = {
          "npxisa",
          npxisa_methods,
          1,                      /* no softc */
  };
  
  static devclass_t npxisa_devclass;
  
  DRIVER_MODULE(npxisa, isa, npxisa_driver, npxisa_devclass, 0, 0);
  #ifndef PC98
  DRIVER_MODULE(npxisa, acpi, npxisa_driver, npxisa_devclass, 0, 0);
  #endif
  #endif /* DEV_ISA */

Cache object: cbd016630003c88725e2e4f0e6065b71