LXR linux/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
  40void 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
  45extern char fpe_type[];
  46#endif
  47
  48static 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
  58static struct notifier_block nwfpe_notifier_block = {
  59        .notifier_call = nwfpe_notify,
  60};
  61
  62/* kernel function prototypes required */
  63void fp_setup(void);
  64
  65/* external declarations for saved kernel symbols */
  66extern void (*kern_fp_enter)(void);
  67
  68/* Original value of fp_enter from kernel before patched by fpe_init. */
  69static void (*orig_fp_enter)(void);
  70
  71/* forward declarations */
  72extern void nwfpe_enter(void);
  73
  74static 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
 101static 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/*
 109ScottB:  November 4, 1998
 110
 111Moved this function out of softfloat-specialize into fpmodule.c.
 112This effectively isolates all the changes required for integrating with the
 113Linux kernel into fpmodule.c.  Porting to NetBSD should only require modifying
 114fpmodule.c to integrate with the NetBSD kernel (I hope!).
 115
 116[1/1/99: Not quite true any more unfortunately.  There is Linux-specific
 117code to access data in user space in some other source files at the 
 118moment (grep for get_user / put_user calls).  --philb]
 119
 120This function is called by the SoftFloat routines to raise a floating
 121point exception.  We check the trap enable byte in the FPSR, and raise
 122a SIGFPE exception if necessary.  If not the relevant bits in the 
 123cumulative 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 */
 128static int debug = ~BIT_IXC;
 129#endif
 130
 131void 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
 169module_init(fpe_init);
 170module_exit(fpe_exit);
 171
 172MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
 173MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
 174MODULE_LICENSE("GPL");
 175
 176#ifdef CONFIG_DEBUG_USER
 177module_param(debug, int, 0644);
 178#endif
 179