arch/arm/nwfpe/fpmodule.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 /*
   4     NetWinder Floating Point Emulator
   5     (c) Rebel.com, 1998-1999
   6     (c) Philip Blundell, 1998-1999
   7
   8     Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
   9
  10 */
  11
  12 #include "fpa11.h"
  13
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16
  17 /* XXX */
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/signal.h>
  22 #include <linux/sched/signal.h>
  23 #include <linux/init.h>
  24
  25 #include <asm/thread_notify.h>
  26
  27 #include "softfloat.h"
  28 #include "fpopcode.h"
  29 #include "fpmodule.h"
  30 #include "fpa11.inl"
  31
  32 /* kernel symbols required for signal handling */
  33 #ifdef CONFIG_FPE_NWFPE_XP
  34 #define NWFPE_BITS "extended"
  35 #else
  36 #define NWFPE_BITS "double"
  37 #endif
  38
  39 #ifdef MODULE
  40 void fp_send_sig(unsigned long sig, struct task_struct *p, int priv);
  41 #else
  42 #define fp_send_sig     send_sig
  43 #define kern_fp_enter   fp_enter
  44
  45 extern char fpe_type[];
  46 #endif
  47
  48 static int nwfpe_notify(struct notifier_block *self, unsigned long cmd, void *v)
  49 {
  50         struct thread_info *thread = v;
  51
  52         if (cmd == THREAD_NOTIFY_FLUSH)
  53                 nwfpe_init_fpa(&thread->fpstate);
  54
  55         return NOTIFY_DONE;
  56 }
  57
  58 static struct notifier_block nwfpe_notifier_block = {
  59         .notifier_call = nwfpe_notify,
  60 };
  61
  62 /* kernel function prototypes required */
  63 void fp_setup(void);
  64
  65 /* external declarations for saved kernel symbols */
  66 extern void (*kern_fp_enter)(void);
  67
  68 /* Original value of fp_enter from kernel before patched by fpe_init. */
  69 static void (*orig_fp_enter)(void);
  70
  71 /* forward declarations */
  72 extern void nwfpe_enter(void);
  73
  74 static int __init fpe_init(void)
  75 {
  76         if (sizeof(FPA11) > sizeof(union fp_state)) {
  77                 pr_err("nwfpe: bad structure size\n");
  78                 return -EINVAL;
  79         }
  80
  81         if (sizeof(FPREG) != 12) {
  82                 pr_err("nwfpe: bad register size\n");
  83                 return -EINVAL;
  84         }
  85         if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
  86                 return 0;
  87
  88         /* Display title, version and copyright information. */
  89         pr_info("NetWinder Floating Point Emulator V0.97 ("
  90                 NWFPE_BITS " precision)\n");
  91
  92         thread_register_notifier(&nwfpe_notifier_block);
  93
  94         /* Save pointer to the old FP handler and then patch ourselves in */
  95         orig_fp_enter = kern_fp_enter;
  96         kern_fp_enter = nwfpe_enter;
  97
  98         return 0;
  99 }
 100
 101 static void __exit fpe_exit(void)
 102 {
 103         thread_unregister_notifier(&nwfpe_notifier_block);
 104         /* Restore the values we saved earlier. */
 105         kern_fp_enter = orig_fp_enter;
 106 }
 107
 108 /*
 109 ScottB:  November 4, 1998
 110
 111 Moved this function out of softfloat-specialize into fpmodule.c.
 112 This effectively isolates all the changes required for integrating with the
 113 Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 114 fpmodule.c to integrate with the NetBSD kernel (I hope!).
 115
 116 [1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 117 code to access data in user space in some other source files at the
 118 moment (grep for get_user / put_user calls).  --philb]
 119
 120 This function is called by the SoftFloat routines to raise a floating
 121 point exception.  We check the trap enable byte in the FPSR, and raise
 122 a SIGFPE exception if necessary.  If not the relevant bits in the
 123 cumulative exceptions flag byte are set and we return.
 124 */
 125
 126 #ifdef CONFIG_DEBUG_USER
 127 /* By default, ignore inexact errors as there are far too many of them to log */
 128 static int debug = ~BIT_IXC;
 129 #endif
 130
 131 void float_raise(signed char flags)
 132 {
 133         register unsigned int fpsr, cumulativeTraps;
 134
 135 #ifdef CONFIG_DEBUG_USER
 136         if (flags & debug)
 137                 printk(KERN_DEBUG
 138                        "NWFPE: %s[%d] takes exception %08x at %ps from %08lx\n",
 139                        current->comm, current->pid, flags,
 140                        __builtin_return_address(0), GET_USERREG()->ARM_pc);
 141 #endif
 142
 143         /* Read fpsr and initialize the cumulativeTraps.  */
 144         fpsr = readFPSR();
 145         cumulativeTraps = 0;
 146
 147         /* For each type of exception, the cumulative trap exception bit is only
 148            set if the corresponding trap enable bit is not set.  */
 149         if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
 150                 cumulativeTraps |= BIT_IXC;
 151         if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
 152                 cumulativeTraps |= BIT_UFC;
 153         if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
 154                 cumulativeTraps |= BIT_OFC;
 155         if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
 156                 cumulativeTraps |= BIT_DZC;
 157         if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
 158                 cumulativeTraps |= BIT_IOC;
 159
 160         /* Set the cumulative exceptions flags.  */
 161         if (cumulativeTraps)
 162                 writeFPSR(fpsr | cumulativeTraps);
 163
 164         /* Raise an exception if necessary.  */
 165         if (fpsr & (flags << 16))
 166                 fp_send_sig(SIGFPE, current, 1);
 167 }
 168
 169 module_init(fpe_init);
 170 module_exit(fpe_exit);
 171
 172 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
 173 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
 174 MODULE_LICENSE("GPL");
 175
 176 #ifdef CONFIG_DEBUG_USER
 177 module_param(debug, int, 0644);
 178 #endif