1 2 /* 3 NetWinder Floating Point Emulator 4 (c) Rebel.com, 1998-1999 5 (c) Philip Blundell, 1998-1999 6 7 Direct questions, comments to Scott Bambrough <scottb@netwinder.org> 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 2 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program; if not, write to the Free Software 21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 22 */ 23 24 #include "fpa11.h" 25 26 #include <linux/module.h> 27 #include <linux/config.h> 28 29 /* XXX */ 30 #include <linux/errno.h> 31 #include <linux/types.h> 32 #include <linux/kernel.h> 33 #include <linux/signal.h> 34 #include <linux/sched.h> 35 #include <linux/init.h> 36 /* XXX */ 37 38 #include "softfloat.h" 39 #include "fpopcode.h" 40 #include "fpmodule.h" 41 #include "fpa11.inl" 42 43 /* kernel symbols required for signal handling */ 44 #ifdef CONFIG_FPE_NWFPE_XP 45 #define NWFPE_BITS "extended" 46 #else 47 #define NWFPE_BITS "double" 48 #endif 49 50 #ifdef MODULE 51 void fp_send_sig(unsigned long sig, struct task_struct *p, int priv); 52 #else 53 #define fp_send_sig send_sig 54 #define kern_fp_enter fp_enter 55 56 extern char fpe_type[]; 57 #endif 58 59 /* kernel function prototypes required */ 60 void fp_setup(void); 61 62 /* external declarations for saved kernel symbols */ 63 extern void (*kern_fp_enter)(void); 64 extern void (*fp_init)(union fp_state *); 65 66 /* Original value of fp_enter from kernel before patched by fpe_init. */ 67 static void (*orig_fp_enter)(void); 68 static void (*orig_fp_init)(union fp_state *); 69 70 /* forward declarations */ 71 extern void nwfpe_enter(void); 72 73 static int __init fpe_init(void) 74 { 75 if (sizeof(FPA11) > sizeof(union fp_state)) { 76 printk(KERN_ERR "nwfpe: bad structure size\n"); 77 return -EINVAL; 78 } 79 80 if (sizeof(FPREG) != 12) { 81 printk(KERN_ERR "nwfpe: bad register size\n"); 82 return -EINVAL; 83 } 84 if (fpe_type[0] && strcmp(fpe_type, "nwfpe")) 85 return 0; 86 87 /* Display title, version and copyright information. */ 88 printk(KERN_WARNING "NetWinder Floating Point Emulator V0.97 (" 89 NWFPE_BITS " precision)\n"); 90 91 /* Save pointer to the old FP handler and then patch ourselves in */ 92 orig_fp_enter = kern_fp_enter; 93 orig_fp_init = fp_init; 94 kern_fp_enter = nwfpe_enter; 95 fp_init = nwfpe_init_fpa; 96 97 return 0; 98 } 99 100 static void __exit fpe_exit(void) 101 { 102 /* Restore the values we saved earlier. */ 103 kern_fp_enter = orig_fp_enter; 104 fp_init = orig_fp_init; 105 } 106 107 /* 108 ScottB: November 4, 1998 109 110 Moved this function out of softfloat-specialize into fpmodule.c. 111 This effectively isolates all the changes required for integrating with the 112 Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying 113 fpmodule.c to integrate with the NetBSD kernel (I hope!). 114 115 [1/1/99: Not quite true any more unfortunately. There is Linux-specific 116 code to access data in user space in some other source files at the 117 moment (grep for get_user / put_user calls). --philb] 118 119 float_exception_flags is a global variable in SoftFloat. 120 121 This function is called by the SoftFloat routines to raise a floating 122 point exception. We check the trap enable byte in the FPSR, and raise 123 a SIGFPE exception if necessary. If not the relevant bits in the 124 cumulative exceptions flag byte are set and we return. 125 */ 126 127 void float_raise(signed char flags) 128 { 129 register unsigned int fpsr, cumulativeTraps; 130 131 #ifdef CONFIG_DEBUG_USER 132 printk(KERN_DEBUG 133 "NWFPE: %s[%d] takes exception %08x at %p from %08lx\n", 134 current->comm, current->pid, flags, 135 __builtin_return_address(0), GET_USERREG()[15]); 136 #endif 137 138 /* Keep SoftFloat exception flags up to date. */ 139 float_exception_flags |= flags; 140 141 /* Read fpsr and initialize the cumulativeTraps. */ 142 fpsr = readFPSR(); 143 cumulativeTraps = 0; 144 145 /* For each type of exception, the cumulative trap exception bit is only 146 set if the corresponding trap enable bit is not set. */ 147 if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC)) 148 cumulativeTraps |= BIT_IXC; 149 if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC)) 150 cumulativeTraps |= BIT_UFC; 151 if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC)) 152 cumulativeTraps |= BIT_OFC; 153 if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC)) 154 cumulativeTraps |= BIT_DZC; 155 if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC)) 156 cumulativeTraps |= BIT_IOC; 157 158 /* Set the cumulative exceptions flags. */ 159 if (cumulativeTraps) 160 writeFPSR(fpsr | cumulativeTraps); 161 162 /* Raise an exception if necessary. */ 163 if (fpsr & (flags << 16)) 164 fp_send_sig(SIGFPE, current, 1); 165 } 166 167 module_init(fpe_init); 168 module_exit(fpe_exit); 169 170 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>"); 171 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)"); 172 MODULE_LICENSE("GPL"); 173