1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* 28 * Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. 29 * Copyright (c) 1988 AT&T 30 * All Rights Reserved 31 */ 32 33 /* 34 * Copyright 2023 Oxide Computer Company 35 */ 36 37 /* 38 * Establish the default settings for the floating-point state for a C language 39 * program: 40 * rounding mode -- round to nearest default by OS, 41 * exceptions enabled -- all masked 42 * sticky bits -- all clear by default by OS. 43 * precision control -- double extended 44 * Set _fp_hw according to what floating-point hardware is available. 45 * Set _sse_hw according to what SSE hardware is available. 46 * Set __flt_rounds according to the rounding mode. 47 */ 48 49 #pragma weak _fpstart = __fpstart 50 51 #include "lint.h" 52 #include <sys/types.h> 53 #include <sys/sysi86.h> /* for SI86FPHW/SI86FPSTART definitions */ 54 #include <sys/fp.h> /* for FPU_CW_INIT and SSE_MXCSR_INIT */ 55 #include <upanic.h> 56 57 extern int __fltrounds(); 58 59 int _fp_hw; /* default: bss: 0 == no hardware */ 60 int _sse_hw; /* default: bss: 0 == no sse */ 61 int __flt_rounds; /* ANSI rounding mode */ 62 63 #define UPANIC_MSG "32-bit FPU init failed!" 64 65 void 66 __fpstart() 67 { 68 /* 69 * query OS for HW status and ensure the x87 and (optional) 70 * SSE control words are (will be) set correctly. 71 */ 72 if ((_sse_hw = sysi86(SI86FPSTART, 73 &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT)) == -1) { 74 /* 75 * Because the system only supports a 64-bit kernel, the above 76 * should always work (we assume it does in 64-bit libc). If it 77 * should fail, we upanic. Note, because the FPU state is 78 * unknown, we use a static message below and don't rely upon 79 * strlen(), but rather compile time lengths. 80 */ 81 upanic(UPANIC_MSG, sizeof (UPANIC_MSG)); 82 } 83 84 /* 85 * At this point the x87 fp environment that has been (or more 86 * hopefully, will be) established by the kernel is: 87 * 88 * affine infinity 0x1000 89 * round to nearest 0x0000 90 * 64-bit doubles 0x0300 91 * precision, underflow, overflow, zero-divide, denorm, invalid masked 92 * 0x003f 93 * 94 * which conforms to the 4th edition i386 ABI definition. 95 * 96 * Additionally, if we have SSE hardware, we've also masked all 97 * the same traps, and have round to nearest. 98 */ 99 100 __flt_rounds = 1; /* ANSI way of saying round-to-nearest */ 101 } 102