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/version.h> 28 29#include <linux/errno.h> 30#include <linux/types.h> 31#include <linux/kernel.h> 32#include <linux/signal.h> 33#include <linux/sched.h> 34#include <linux/init.h> 35 36#include "softfloat.h" 37#include "fpopcode.h" 38#include "fpmodule.h" 39#include "fpa11.inl" 40 41/* kernel symbols required for signal handling */ 42typedef struct task_struct* PTASK; 43 44#ifdef MODULE 45void fp_send_sig(unsigned long sig, PTASK p, int priv); 46 47MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>"); 48MODULE_DESCRIPTION("NWFPE floating point emulator"); 49 50#else 51#define fp_send_sig send_sig 52#define kern_fp_enter fp_enter 53 54extern char fpe_type[]; 55#endif 56 57/* kernel function prototypes required */ 58void fp_setup(void); 59 60/* external declarations for saved kernel symbols */ 61extern void (*kern_fp_enter)(void); 62 63/* Original value of fp_enter from kernel before patched by fpe_init. */ 64static void (*orig_fp_enter)(void); 65 66/* forward declarations */ 67extern void nwfpe_enter(void); 68 69#ifdef MODULE 70/* 71 * Return 0 if we can be unloaded. This can only happen if 72 * kern_fp_enter is still pointing at nwfpe_enter 73 */ 74static int fpe_unload(void) 75{ 76 return (kern_fp_enter == nwfpe_enter) ? 0 : 1; 77} 78#endif 79 80static int __init fpe_init(void) 81{ 82 if (sizeof(FPA11) > sizeof(union fp_state)) { 83 printk(KERN_ERR "nwfpe: bad structure size\n"); 84 return -EINVAL; 85 } 86 87 if (sizeof(FPREG) != 12) { 88 printk(KERN_ERR "nwfpe: bad register size\n"); 89 return -EINVAL; 90 } 91 92#ifdef MODULE 93 if (!mod_member_present(&__this_module, can_unload)) 94 return -EINVAL; 95 __this_module.can_unload = fpe_unload; 96#else 97 if (fpe_type[0] && strcmp(fpe_type, "nwfpe")) 98 return 0; 99#endif 100 101 /* Display title, version and copyright information. */ 102 printk(KERN_WARNING "NetWinder Floating Point Emulator V0.95 " 103 "(c) 1998-1999 Rebel.com\n"); 104 105 /* Save pointer to the old FP handler and then patch ourselves in */ 106 orig_fp_enter = kern_fp_enter; 107 kern_fp_enter = nwfpe_enter; 108 109 return 0; 110} 111 112static void __exit fpe_exit(void) 113{ 114 /* Restore the values we saved earlier. */ 115 kern_fp_enter = orig_fp_enter; 116} 117 118/* 119ScottB: November 4, 1998 120 121Moved this function out of softfloat-specialize into fpmodule.c. 122This effectively isolates all the changes required for integrating with the 123Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying 124fpmodule.c to integrate with the NetBSD kernel (I hope!). 125 126[1/1/99: Not quite true any more unfortunately. There is Linux-specific 127code to access data in user space in some other source files at the 128moment (grep for get_user / put_user calls). --philb] 129 130float_exception_flags is a global variable in SoftFloat. 131 132This function is called by the SoftFloat routines to raise a floating 133point exception. We check the trap enable byte in the FPSR, and raise 134a SIGFPE exception if necessary. If not the relevant bits in the 135cumulative exceptions flag byte are set and we return. 136*/ 137 138void float_raise(signed char flags) 139{ 140 register unsigned int fpsr, cumulativeTraps; 141 142#ifdef CONFIG_DEBUG_USER 143 printk(KERN_DEBUG "NWFPE: %s[%d] takes exception %08x at %p from %08x\n", 144 current->comm, current->pid, flags, 145 __builtin_return_address(0), GET_USERREG()[15]); 146#endif 147 148 /* Keep SoftFloat exception flags up to date. */ 149 float_exception_flags |= flags; 150 151 /* Read fpsr and initialize the cumulativeTraps. */ 152 fpsr = readFPSR(); 153 cumulativeTraps = 0; 154 155 /* For each type of exception, the cumulative trap exception bit is only 156 set if the corresponding trap enable bit is not set. */ 157 if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC)) 158 cumulativeTraps |= BIT_IXC; 159 if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC)) 160 cumulativeTraps |= BIT_UFC; 161 if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC)) 162 cumulativeTraps |= BIT_OFC; 163 if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC)) 164 cumulativeTraps |= BIT_DZC; 165 if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC)) 166 cumulativeTraps |= BIT_IOC; 167 168 /* Set the cumulative exceptions flags. */ 169 if (cumulativeTraps) 170 writeFPSR(fpsr | cumulativeTraps); 171 172 /* Raise an exception if necessary. */ 173 if (fpsr & (flags << 16)) 174 fp_send_sig(SIGFPE, current, 1); 175} 176 177module_init(fpe_init); 178module_exit(fpe_exit); 179