Annotation of sys/arch/amd64/amd64/fpu.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: fpu.c,v 1.12 2006/11/29 12:24:17 miod Exp $ */
! 2: /* $NetBSD: fpu.c,v 1.1 2003/04/26 18:39:28 fvdl Exp $ */
! 3:
! 4: /*-
! 5: * Copyright (c) 1994, 1995, 1998 Charles M. Hannum. All rights reserved.
! 6: * Copyright (c) 1990 William Jolitz.
! 7: * Copyright (c) 1991 The Regents of the University of California.
! 8: * All rights reserved.
! 9: *
! 10: * Redistribution and use in source and binary forms, with or without
! 11: * modification, are permitted provided that the following conditions
! 12: * are met:
! 13: * 1. Redistributions of source code must retain the above copyright
! 14: * notice, this list of conditions and the following disclaimer.
! 15: * 2. Redistributions in binary form must reproduce the above copyright
! 16: * notice, this list of conditions and the following disclaimer in the
! 17: * documentation and/or other materials provided with the distribution.
! 18: * 3. Neither the name of the University nor the names of its contributors
! 19: * may be used to endorse or promote products derived from this software
! 20: * without specific prior written permission.
! 21: *
! 22: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 23: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 24: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 25: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 26: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 27: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 28: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 29: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 30: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 31: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 32: * SUCH DAMAGE.
! 33: *
! 34: * @(#)npx.c 7.2 (Berkeley) 5/12/91
! 35: */
! 36:
! 37: /*
! 38: * XXXfvdl update copyright notice. this started out as a stripped isa/npx.c
! 39: */
! 40:
! 41: #include <sys/param.h>
! 42: #include <sys/systm.h>
! 43: #include <sys/conf.h>
! 44: #include <sys/file.h>
! 45: #include <sys/proc.h>
! 46: #include <sys/user.h>
! 47: #include <sys/ioctl.h>
! 48: #include <sys/device.h>
! 49: #include <sys/vmmeter.h>
! 50: #include <sys/signalvar.h>
! 51:
! 52: #include <uvm/uvm_extern.h>
! 53:
! 54: #include <machine/bus.h>
! 55: #include <machine/cpu.h>
! 56: #include <machine/intr.h>
! 57: #include <machine/cpufunc.h>
! 58: #include <machine/pcb.h>
! 59: #include <machine/trap.h>
! 60: #include <machine/specialreg.h>
! 61: #include <machine/fpu.h>
! 62:
! 63: #include <dev/isa/isareg.h>
! 64: #include <dev/isa/isavar.h>
! 65:
! 66: /*
! 67: * We do lazy initialization and switching using the TS bit in cr0 and the
! 68: * MDP_USEDFPU bit in mdproc.
! 69: *
! 70: * DNA exceptions are handled like this:
! 71: *
! 72: * 1) If there is no FPU, return and go to the emulator.
! 73: * 2) If someone else has used the FPU, save its state into that process' PCB.
! 74: * 3a) If MDP_USEDFPU is not set, set it and initialize the FPU.
! 75: * 3b) Otherwise, reload the process' previous FPU state.
! 76: *
! 77: * When a process is created or exec()s, its saved cr0 image has the TS bit
! 78: * set and the MDP_USEDFPU bit clear. The MDP_USEDFPU bit is set when the
! 79: * process first gets a DNA and the FPU is initialized. The TS bit is turned
! 80: * off when the FPU is used, and turned on again later when the process' FPU
! 81: * state is saved.
! 82: */
! 83:
! 84: #define fninit() __asm("fninit")
! 85: #define fwait() __asm("fwait")
! 86: #define fnclex() __asm("fnclex")
! 87: #define fxsave(addr) __asm("fxsave %0" : "=m" (*addr))
! 88: #define fxrstor(addr) __asm("fxrstor %0" : : "m" (*addr))
! 89: #define ldmxcsr(addr) __asm("ldmxcsr %0" : : "m" (*addr))
! 90: #define fldcw(addr) __asm("fldcw %0" : : "m" (*addr))
! 91: #define clts() __asm("clts")
! 92: #define stts() lcr0(rcr0() | CR0_TS)
! 93:
! 94: void fpudna(struct cpu_info *);
! 95: static int x86fpflags_to_siginfo(u_int32_t);
! 96:
! 97: /*
! 98: * Init the FPU.
! 99: */
! 100: void
! 101: fpuinit(struct cpu_info *ci)
! 102: {
! 103: lcr0(rcr0() & ~(CR0_EM|CR0_TS));
! 104: fninit();
! 105: lcr0(rcr0() | (CR0_TS));
! 106: }
! 107:
! 108: /*
! 109: * Record the FPU state and reinitialize it all except for the control word.
! 110: * Then generate a SIGFPE.
! 111: *
! 112: * Reinitializing the state allows naive SIGFPE handlers to longjmp without
! 113: * doing any fixups.
! 114: */
! 115:
! 116: void
! 117: fputrap(struct trapframe *frame)
! 118: {
! 119: struct proc *p = curcpu()->ci_fpcurproc;
! 120: struct savefpu *sfp = &p->p_addr->u_pcb.pcb_savefpu;
! 121: u_int32_t statbits;
! 122: u_int16_t cw;
! 123: int code;
! 124: union sigval sv;
! 125:
! 126: #ifdef DIAGNOSTIC
! 127: /*
! 128: * At this point, fpcurproc should be curproc. If it wasn't,
! 129: * the TS bit should be set, and we should have gotten a DNA exception.
! 130: */
! 131: if (p != curproc)
! 132: panic("fputrap: wrong proc");
! 133: #endif
! 134:
! 135: fxsave(sfp);
! 136: if (frame->tf_trapno == T_XMM) {
! 137: statbits = sfp->fp_fxsave.fx_mxcsr;
! 138: } else {
! 139: fninit();
! 140: fwait();
! 141: cw = sfp->fp_fxsave.fx_fcw;
! 142: fldcw(&cw);
! 143: fwait();
! 144: statbits = sfp->fp_fxsave.fx_fsw;
! 145: }
! 146: sfp->fp_ex_tw = sfp->fp_fxsave.fx_ftw;
! 147: sfp->fp_ex_sw = sfp->fp_fxsave.fx_fsw;
! 148: code = x86fpflags_to_siginfo (statbits);
! 149: sv.sival_ptr = (void *)frame->tf_rip; /* XXX - ? */
! 150: KERNEL_PROC_LOCK(p);
! 151: trapsignal(p, SIGFPE, frame->tf_err, code, sv);
! 152: KERNEL_PROC_UNLOCK(p);
! 153: }
! 154:
! 155: static int
! 156: x86fpflags_to_siginfo(u_int32_t flags)
! 157: {
! 158: int i;
! 159: static int x86fp_siginfo_table[] = {
! 160: FPE_FLTINV, /* bit 0 - invalid operation */
! 161: FPE_FLTRES, /* bit 1 - denormal operand */
! 162: FPE_FLTDIV, /* bit 2 - divide by zero */
! 163: FPE_FLTOVF, /* bit 3 - fp overflow */
! 164: FPE_FLTUND, /* bit 4 - fp underflow */
! 165: FPE_FLTRES, /* bit 5 - fp precision */
! 166: FPE_FLTINV, /* bit 6 - stack fault */
! 167: };
! 168:
! 169: for (i=0;i < sizeof(x86fp_siginfo_table)/sizeof(int); i++) {
! 170: if (flags & (1 << i))
! 171: return (x86fp_siginfo_table[i]);
! 172: }
! 173: /* punt if flags not set */
! 174: return (FPE_FLTINV);
! 175: }
! 176:
! 177: /*
! 178: * Implement device not available (DNA) exception
! 179: *
! 180: * If we were the last process to use the FPU, we can simply return.
! 181: * Otherwise, we save the previous state, if necessary, and restore our last
! 182: * saved state.
! 183: */
! 184: void
! 185: fpudna(struct cpu_info *ci)
! 186: {
! 187: struct proc *p;
! 188: int s;
! 189:
! 190: if (ci->ci_fpsaving) {
! 191: printf("recursive fpu trap; cr0=%x\n", rcr0());
! 192: return;
! 193: }
! 194:
! 195: s = splipi();
! 196:
! 197: #ifdef MULTIPROCESSOR
! 198: p = ci->ci_curproc;
! 199: #else
! 200: p = curproc;
! 201: #endif
! 202:
! 203: /*
! 204: * Initialize the FPU state to clear any exceptions. If someone else
! 205: * was using the FPU, save their state.
! 206: */
! 207: if (ci->ci_fpcurproc != NULL && ci->ci_fpcurproc != p) {
! 208: fpusave_cpu(ci, 1);
! 209: uvmexp.fpswtch++;
! 210: } else {
! 211: clts();
! 212: fninit();
! 213: fwait();
! 214: stts();
! 215: }
! 216: splx(s);
! 217:
! 218: if (p == NULL) {
! 219: clts();
! 220: return;
! 221: }
! 222:
! 223: KDASSERT(ci->ci_fpcurproc == NULL);
! 224: #ifndef MULTIPROCESSOR
! 225: KDASSERT(p->p_addr->u_pcb.pcb_fpcpu == NULL);
! 226: #else
! 227: if (p->p_addr->u_pcb.pcb_fpcpu != NULL)
! 228: fpusave_proc(p, 1);
! 229: #endif
! 230:
! 231: p->p_addr->u_pcb.pcb_cr0 &= ~CR0_TS;
! 232: clts();
! 233:
! 234: s = splipi();
! 235: ci->ci_fpcurproc = p;
! 236: p->p_addr->u_pcb.pcb_fpcpu = ci;
! 237: splx(s);
! 238:
! 239: if ((p->p_md.md_flags & MDP_USEDFPU) == 0) {
! 240: fldcw(&p->p_addr->u_pcb.pcb_savefpu.fp_fxsave.fx_fcw);
! 241: ldmxcsr(&p->p_addr->u_pcb.pcb_savefpu.fp_fxsave.fx_mxcsr);
! 242: p->p_md.md_flags |= MDP_USEDFPU;
! 243: } else {
! 244: static double zero = 0.0;
! 245:
! 246: /*
! 247: * amd fpu does not restore fip, fdp, fop on fxrstor
! 248: * thus leaking other process's execution history.
! 249: */
! 250: fnclex();
! 251: __asm __volatile("ffree %%st(7)\n\tfld %0" : : "m" (zero));
! 252: fxrstor(&p->p_addr->u_pcb.pcb_savefpu);
! 253: }
! 254: }
! 255:
! 256:
! 257: void
! 258: fpusave_cpu(struct cpu_info *ci, int save)
! 259: {
! 260: struct proc *p;
! 261: int s;
! 262:
! 263: KDASSERT(ci == curcpu());
! 264:
! 265: p = ci->ci_fpcurproc;
! 266: if (p == NULL)
! 267: return;
! 268:
! 269: if (save) {
! 270: #ifdef DIAGNOSTIC
! 271: if (ci->ci_fpsaving != 0)
! 272: panic("fpusave_cpu: recursive save!");
! 273: #endif
! 274: /*
! 275: * Set ci->ci_fpsaving, so that any pending exception will be
! 276: * thrown away. (It will be caught again if/when the FPU
! 277: * state is restored.)
! 278: */
! 279: clts();
! 280: ci->ci_fpsaving = 1;
! 281: fxsave(&p->p_addr->u_pcb.pcb_savefpu);
! 282: ci->ci_fpsaving = 0;
! 283: }
! 284:
! 285: stts();
! 286: p->p_addr->u_pcb.pcb_cr0 |= CR0_TS;
! 287:
! 288: s = splipi();
! 289: p->p_addr->u_pcb.pcb_fpcpu = NULL;
! 290: ci->ci_fpcurproc = NULL;
! 291: splx(s);
! 292: }
! 293:
! 294: /*
! 295: * Save p's FPU state, which may be on this processor or another processor.
! 296: */
! 297: void
! 298: fpusave_proc(struct proc *p, int save)
! 299: {
! 300: struct cpu_info *ci = curcpu();
! 301: struct cpu_info *oci;
! 302:
! 303: KDASSERT(p->p_addr != NULL);
! 304:
! 305: oci = p->p_addr->u_pcb.pcb_fpcpu;
! 306: if (oci == NULL)
! 307: return;
! 308:
! 309: #if defined(MULTIPROCESSOR)
! 310: if (oci == ci) {
! 311: int s = splipi();
! 312: fpusave_cpu(ci, save);
! 313: splx(s);
! 314: } else {
! 315: #ifdef DIAGNOSTIC
! 316: int spincount;
! 317: #endif
! 318:
! 319: x86_send_ipi(oci,
! 320: save ? X86_IPI_SYNCH_FPU : X86_IPI_FLUSH_FPU);
! 321:
! 322: #ifdef DIAGNOSTIC
! 323: spincount = 0;
! 324: #endif
! 325: while (p->p_addr->u_pcb.pcb_fpcpu != NULL)
! 326: #ifdef DIAGNOSTIC
! 327: {
! 328: spincount++;
! 329: if (spincount > 10000000) {
! 330: panic("fp_save ipi didn't");
! 331: }
! 332: }
! 333: #else
! 334: __splbarrier(); /* XXX replace by generic barrier */
! 335: ;
! 336: #endif
! 337: }
! 338: #else
! 339: KASSERT(ci->ci_fpcurproc == p);
! 340: fpusave_cpu(ci, save);
! 341: #endif
! 342: }
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to fpu.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / sys / arch / amd64 / amd64