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/9.2/sys/i386/isa/npx.c 239996 2012-09-01 15:59:09Z kib $");
    
    #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/resource.h>
    #include <machine/specialreg.h>
    #include <machine/segments.h>
    #include <machine/ucontext.h>
    
    #include <machine/intr_machdep.h>
    #ifdef XEN
    #include <machine/xen/xen-os.h>
    #include <xen/hypervisor.h>
    #endif
    
    #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.
     */
    
    #if defined(__GNUCLIKE_ASM) && !defined(lint)
    
    #define fldcw(cw)               __asm __volatile("fldcw %0" : : "m" (cw))
    #define fnclex()                __asm __volatile("fnclex")
    #define fninit()                __asm __volatile("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" : "=am" (*(addr)))
    #define fp_divide_by_0()        __asm __volatile( \
                                        "fldz; fld1; fdiv %st,%st(1); fnop")
    #define frstor(addr)            __asm __volatile("frstor %0" : : "m" (*(addr)))
    #ifdef CPU_ENABLE_SSE
   #define fxrstor(addr)           __asm __volatile("fxrstor %0" : : "m" (*(addr)))
   #define fxsave(addr)            __asm __volatile("fxsave %0" : "=m" (*(addr)))
   #define stmxcsr(addr)           __asm __volatile("stmxcsr %0" : : "m" (*(addr)))
   #endif
   #else   /* !(__GNUCLIKE_ASM && !lint) */
   
   void    fldcw(u_short cw);
   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);
   void    stmxcsr(u_int *csr);
   #endif
   
   #endif  /* __GNUCLIKE_ASM && !lint */
   
   #ifdef XEN
   #define start_emulating()       (HYPERVISOR_fpu_taskswitch(1))
   #define stop_emulating()        (HYPERVISOR_fpu_taskswitch(0))
   #else
   #define start_emulating()       load_cr0(rcr0() | CR0_TS)
   #define stop_emulating()        clts()
   #endif
   
   #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)
   #define SET_FPU_CW(savefpu, value) do { \
           if (cpu_fxsr) \
                   (savefpu)->sv_xmm.sv_env.en_cw = (value); \
           else \
                   (savefpu)->sv_87.sv_env.en_cw = (value); \
   } while (0)
   #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)
   #define SET_FPU_CW(savefpu, value) \
           (savefpu)->sv_87.sv_env.en_cw = (value)
   #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  int     npx_probe(device_t dev);
   
   int     hw_float;
   
   SYSCTL_INT(_hw, HW_FLOATINGPT, floatingpoint, CTLFLAG_RD,
       &hw_float, 0, "Floating point instructions executed in hardware");
   
   static  volatile u_int          npx_traps_while_probing;
   static  union savefpu           npx_initialstate;
   
   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");
   }
   
   /*
    * Probe routine.  Set flags to tell npxattach() what to do.  Set up an
    * interrupt handler if npx needs to use interrupts.
    */
   static int
   npx_probe(device_t dev)
   {
           struct gate_descriptor save_idt_npxtrap;
           u_short control, status;
   
           device_set_desc(dev, "math processor");
   
           /*
            * Modern CPUs all have an FPU that uses the INT16 interface
            * and provide a simple way to verify that, so handle the
            * common case right away.
            */
           if (cpu_feature & CPUID_FPU) {
                   hw_float = 1;
                   device_quiet(dev);
                   return (0);
           }
   
           save_idt_npxtrap = idt[IDT_MF];
           setidt(IDT_MF, probetrap, SDT_SYS386TGT, SEL_KPL,
               GSEL(GCODE_SEL, SEL_KPL));
   
           /*
            * 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();
   
           /*
            * 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_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) {
                           /*
                            * 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.
                            */
                           hw_float = 1;
                           return (0);
   #endif
                           npx_traps_while_probing = 0;
                           fp_divide_by_0();
                           if (npx_traps_while_probing != 0) {
                                   /*
                                    * Good, exception 16 works.
                                    */
                                   hw_float = 1;
                                   goto cleanup;
                           }
                           device_printf(dev,
           "FPU does not use exception 16 for error reporting\n");
                           goto cleanup;
                   }
           }
   
           /*
            * Probe failed.  Floating point simply won't work.
            * Notify user and disable FPU/MMX/SSE instruction execution.
            */
           device_printf(dev, "WARNING: no FPU!\n");
           __asm __volatile("smsw %%ax; orb %0,%%al; lmsw %%ax" : :
               "n" (CR0_EM | CR0_MP) : "ax");
   
   cleanup:
           idt[IDT_MF] = save_idt_npxtrap;
           return (hw_float ? 0 : ENXIO);
   }
   
   /*
    * Attach routine - announce which it is, and wire into system
    */
   static int
   npx_attach(device_t dev)
   {
   
           npxinit();
           critical_enter();
           stop_emulating();
           fpusave(&npx_initialstate);
           start_emulating();
   #ifdef CPU_ENABLE_SSE
           if (cpu_fxsr) {
                   if (npx_initialstate.sv_xmm.sv_env.en_mxcsr_mask)
                           cpu_mxcsr_mask = 
                               npx_initialstate.sv_xmm.sv_env.en_mxcsr_mask;
                   else
                           cpu_mxcsr_mask = 0xFFBF;
                   bzero(npx_initialstate.sv_xmm.sv_fp,
                       sizeof(npx_initialstate.sv_xmm.sv_fp));
                   bzero(npx_initialstate.sv_xmm.sv_xmm,
                       sizeof(npx_initialstate.sv_xmm.sv_xmm));
                   /* XXX might need even more zeroing. */
           } else
   #endif
                   bzero(npx_initialstate.sv_87.sv_ac,
                       sizeof(npx_initialstate.sv_87.sv_ac));
           critical_exit();
   
           return (0);
   }
   
   /*
    * Initialize floating point unit.
    */
   void
   npxinit(void)
   {
           static union savefpu dummy;
           register_t saveintr;
           u_short control;
   
           if (!hw_float)
                   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.
            *
            * It is too early for critical_enter() to work on AP.
            */
           saveintr = 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
           control = __INITIAL_NPXCW__;
           fldcw(control);
           start_emulating();
           intr_restore(saveintr);
   }
   
   /*
    * Free coprocessor (if we have it).
    */
   void
   npxexit(td)
           struct thread *td;
   {
   
           critical_enter();
           if (curthread == PCPU_GET(fpcurthread))
                   npxsave(curpcb->pcb_save);
           critical_exit();
   #ifdef NPX_DEBUG
           if (hw_float) {
                   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 (!hw_float)
                   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 */
   };
   
   /*
    * Read the FP status and control words, then generate si_code value
    * for SIGFPE.  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.
    *
    * Some time ago, we cleared the x87 exceptions with FNCLEX there.
    * Clearing exceptions was necessary mainly to avoid IRQ13 bugs.  The
    * usermode code which understands the FPU hardware enough to enable
    * the exceptions, can also handle clearing the exception state in the
    * handler.  The only consequence of not clearing the exception is the
    * rethrow of the SIGFPE on return from the signal handler and
    * reexecution of the corresponding instruction.
    *
    * For XMM traps, the exceptions were never cleared.
    */
   int
   npxtrap_x87(void)
   {
           u_short control, status;
   
           if (!hw_float) {
                   printf(
           "npxtrap_x87: fpcurthread = %p, curthread = %p, hw_float = %d\n",
                          PCPU_GET(fpcurthread), curthread, hw_float);
                   panic("npxtrap from nowhere");
           }
           critical_enter();
   
           /*
            * 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);
           }
           critical_exit();
           return (fpetable[status & ((~control & 0x3f) | 0x40)]);
   }
   
   #ifdef CPU_ENABLE_SSE
   int
   npxtrap_sse(void)
   {
           u_int mxcsr;
   
           if (!hw_float) {
                   printf(
           "npxtrap_sse: fpcurthread = %p, curthread = %p, hw_float = %d\n",
                          PCPU_GET(fpcurthread), curthread, hw_float);
                   panic("npxtrap from nowhere");
           }
           critical_enter();
           if (PCPU_GET(fpcurthread) != curthread)
                   mxcsr = curthread->td_pcb->pcb_save->sv_xmm.sv_env.en_mxcsr;
           else
                   stmxcsr(&mxcsr);
           critical_exit();
           return (fpetable[(mxcsr & (~mxcsr >> 7)) & 0x3f]);
   }
   #endif
   
   /*
    * 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(void)
   {
   
           if (!hw_float)
                   return (0);
           critical_enter();
           if (PCPU_GET(fpcurthread) == curthread) {
                   printf("npxdna: fpcurthread == curthread %d times\n",
                       ++err_count);
                   stop_emulating();
                   critical_exit();
                   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");
           }
           stop_emulating();
           /*
            * Record new context early in case frstor causes an IRQ13.
            */
           PCPU_SET(fpcurthread, curthread);
   
   #ifdef CPU_ENABLE_SSE
           if (cpu_fxsr)
                   fpu_clean_state();
   #endif
   
           if ((curpcb->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
                    * load an initial state.
                    */
                   fpurstor(&npx_initialstate);
                   if (curpcb->pcb_initial_npxcw != __INITIAL_NPXCW__)
                           fldcw(curpcb->pcb_initial_npxcw);
                   curpcb->pcb_flags |= PCB_NPXINITDONE;
                   if (PCB_USER_FPU(curpcb))
                           curpcb->pcb_flags |= PCB_NPXUSERINITDONE;
           } else {
                   /*
                    * The following fpurstor() 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(curpcb->pcb_save);
           }
           critical_exit();
   
           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);
   }
   
   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);
           KASSERT(td == curthread, ("fpudrop: fpcurthread != curthread"));
           CRITICAL_ASSERT(td);
           PCPU_SET(fpcurthread, NULL);
           td->td_pcb->pcb_flags &= ~PCB_NPXINITDONE;
           start_emulating();
   }
   
   /*
    * Get the user state of the FPU into pcb->pcb_user_save without
    * dropping ownership (if possible).  It returns the FPU ownership
    * status.
    */
   int
   npxgetregs(struct thread *td)
   {
           struct pcb *pcb;
   
           if (!hw_float)
                   return (_MC_FPOWNED_NONE);
   
           pcb = td->td_pcb;
           if ((pcb->pcb_flags & PCB_NPXINITDONE) == 0) {
                   bcopy(&npx_initialstate, &pcb->pcb_user_save,
                       sizeof(npx_initialstate));
                   SET_FPU_CW(&pcb->pcb_user_save, pcb->pcb_initial_npxcw);
                   npxuserinited(td);
                   return (_MC_FPOWNED_PCB);
           }
           critical_enter();
           if (td == PCPU_GET(fpcurthread)) {
                   fpusave(&pcb->pcb_user_save);
   #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();
                   critical_exit();
                   return (_MC_FPOWNED_FPU);
           } else {
                   critical_exit();
                   return (_MC_FPOWNED_PCB);
           }
   }
   
   void
   npxuserinited(struct thread *td)
   {
           struct pcb *pcb;
   
           pcb = td->td_pcb;
           if (PCB_USER_FPU(pcb))
                   pcb->pcb_flags |= PCB_NPXINITDONE;
           pcb->pcb_flags |= PCB_NPXUSERINITDONE;
   }
   
   
   void
   npxsetregs(struct thread *td, union savefpu *addr)
   {
           struct pcb *pcb;
   
           if (!hw_float)
                   return;
   
           pcb = td->td_pcb;
           critical_enter();
           if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {
   #ifdef CPU_ENABLE_SSE
                   if (!cpu_fxsr)
   #endif
                           fnclex();       /* As in npxdrop(). */
                   if (((uintptr_t)addr & 0xf) != 0) {
                           bcopy(addr, &pcb->pcb_user_save, sizeof(*addr));
                           fpurstor(&pcb->pcb_user_save);
                   } else
                           fpurstor(addr);
                   critical_exit();
                   pcb->pcb_flags |= PCB_NPXUSERINITDONE | PCB_NPXINITDONE;
           } else {
                   critical_exit();
                   bcopy(addr, &pcb->pcb_user_save, sizeof(*addr));
                   npxuserinited(td);
           }
   }
   
   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 void
   fpu_clean_state(void)
   {
           static float dummy_variable = 0.0;
           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); flds %0" : : "m" (dummy_variable));
   }
   #endif /* CPU_ENABLE_SSE */
   
   static void
   fpurstor(addr)
           union savefpu *addr;
   {
   
   #ifdef CPU_ENABLE_SSE
           if (cpu_fxsr)
                   fxrstor(addr);
           else
   #endif
                   frstor(addr);
   }
   
   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 */
  
  static MALLOC_DEFINE(M_FPUKERN_CTX, "fpukern_ctx",
      "Kernel contexts for FPU state");
  
  #define XSAVE_AREA_ALIGN        64
  
  #define FPU_KERN_CTX_NPXINITDONE 0x01
  
  struct fpu_kern_ctx {
          union savefpu *prev;
          uint32_t flags;
          char hwstate1[];
  };
  
  struct fpu_kern_ctx *
  fpu_kern_alloc_ctx(u_int flags)
  {
          struct fpu_kern_ctx *res;
          size_t sz;
  
          sz = sizeof(struct fpu_kern_ctx) + XSAVE_AREA_ALIGN +
              sizeof(union savefpu);
          res = malloc(sz, M_FPUKERN_CTX, ((flags & FPU_KERN_NOWAIT) ?
              M_NOWAIT : M_WAITOK) | M_ZERO);
          return (res);
  }
  
  void
  fpu_kern_free_ctx(struct fpu_kern_ctx *ctx)
  {
  
          /* XXXKIB clear the memory ? */
          free(ctx, M_FPUKERN_CTX);
  }
  
  static union savefpu *
  fpu_kern_ctx_savefpu(struct fpu_kern_ctx *ctx)
  {
          vm_offset_t p;
  
          p = (vm_offset_t)&ctx->hwstate1;
          p = roundup2(p, XSAVE_AREA_ALIGN);
          return ((union savefpu *)p);
  }
  
  int
  fpu_kern_enter(struct thread *td, struct fpu_kern_ctx *ctx, u_int flags)
  {
          struct pcb *pcb;
  
          pcb = td->td_pcb;
          KASSERT(!PCB_USER_FPU(pcb) || pcb->pcb_save == &pcb->pcb_user_save,
              ("mangled pcb_save"));
          ctx->flags = 0;
          if ((pcb->pcb_flags & PCB_NPXINITDONE) != 0)
                  ctx->flags |= FPU_KERN_CTX_NPXINITDONE;
          npxexit(td);
          ctx->prev = pcb->pcb_save;
          pcb->pcb_save = fpu_kern_ctx_savefpu(ctx);
          pcb->pcb_flags |= PCB_KERNNPX;
          pcb->pcb_flags &= ~PCB_NPXINITDONE;
          return (0);
  }
  
  int
  fpu_kern_leave(struct thread *td, struct fpu_kern_ctx *ctx)
  {
          struct pcb *pcb;
  
          pcb = td->td_pcb;
          critical_enter();
          if (curthread == PCPU_GET(fpcurthread))
                  npxdrop();
          critical_exit();
          pcb->pcb_save = ctx->prev;
          if (pcb->pcb_save == &pcb->pcb_user_save) {
                  if ((pcb->pcb_flags & PCB_NPXUSERINITDONE) != 0)
                          pcb->pcb_flags |= PCB_NPXINITDONE;
                  else
                          pcb->pcb_flags &= ~PCB_NPXINITDONE;
                  pcb->pcb_flags &= ~PCB_KERNNPX;
          } else {
                  if ((ctx->flags & FPU_KERN_CTX_NPXINITDONE) != 0)
                          pcb->pcb_flags |= PCB_NPXINITDONE;
                  else
                          pcb->pcb_flags &= ~PCB_NPXINITDONE;
                  KASSERT(!PCB_USER_FPU(pcb), ("unpaired fpu_kern_leave"));
          }
          return (0);
  }
  
  int
  fpu_kern_thread(u_int flags)
  {
          struct pcb *pcb;
  
          pcb = curpcb;
          KASSERT((curthread->td_pflags & TDP_KTHREAD) != 0,
              ("Only kthread may use fpu_kern_thread"));
          KASSERT(curpcb->pcb_save == &curpcb->pcb_user_save,
              ("mangled pcb_save"));
          KASSERT(PCB_USER_FPU(curpcb), ("recursive call"));
  
          curpcb->pcb_flags |= PCB_KERNNPX;
          return (0);
  }
  
  int
  is_fpu_kern_thread(u_int flags)
  {
  
          if ((curthread->td_pflags & TDP_KTHREAD) == 0)
                  return (0);
          return ((curpcb->pcb_flags & PCB_KERNNPX) != 0);
  }

Cache object: 3c37cade1457e996a16e516875dde78c