arch/arm/vfp/vfpmodule.c

   1 /*
   2  *  linux/arch/arm/vfp/vfpmodule.c
   3  *
   4  *  Copyright (C) 2004 ARM Limited.
   5  *  Written by Deep Blue Solutions Limited.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/signal.h>
  15 #include <linux/sched.h>
  16 #include <linux/init.h>
  17
  18 #include <asm/thread_notify.h>
  19 #include <asm/vfp.h>
  20
  21 #include "vfpinstr.h"
  22 #include "vfp.h"
  23
  24 /*
  25  * Our undef handlers (in entry.S)
  26  */
  27 void vfp_testing_entry(void);
  28 void vfp_support_entry(void);
  29
  30 void (*vfp_vector)(void) = vfp_testing_entry;
  31 union vfp_state *last_VFP_context;
  32
  33 /*
  34  * Dual-use variable.
  35  * Used in startup: set to non-zero if VFP checks fail
  36  * After startup, holds VFP architecture
  37  */
  38 unsigned int VFP_arch;
  39
  40 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
  41 {
  42         struct thread_info *thread = v;
  43         union vfp_state *vfp;
  44
  45         if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
  46                 /*
  47                  * Always disable VFP so we can lazily save/restore the
  48                  * old state.
  49                  */
  50                 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
  51                 return NOTIFY_DONE;
  52         }
  53
  54         vfp = &thread->vfpstate;
  55         if (cmd == THREAD_NOTIFY_FLUSH) {
  56                 /*
  57                  * Per-thread VFP initialisation.
  58                  */
  59                 memset(vfp, 0, sizeof(union vfp_state));
  60
  61                 vfp->hard.fpexc = FPEXC_ENABLE;
  62                 vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
  63
  64                 /*
  65                  * Disable VFP to ensure we initialise it first.
  66                  */
  67                 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
  68         }
  69
  70         /* flush and release case: Per-thread VFP cleanup. */
  71         if (last_VFP_context == vfp)
  72                 last_VFP_context = NULL;
  73
  74         return NOTIFY_DONE;
  75 }
  76
  77 static struct notifier_block vfp_notifier_block = {
  78         .notifier_call  = vfp_notifier,
  79 };
  80
  81 /*
  82  * Raise a SIGFPE for the current process.
  83  * sicode describes the signal being raised.
  84  */
  85 void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
  86 {
  87         siginfo_t info;
  88
  89         memset(&info, 0, sizeof(info));
  90
  91         info.si_signo = SIGFPE;
  92         info.si_code = sicode;
  93         info.si_addr = (void __user *)(instruction_pointer(regs) - 4);
  94
  95         /*
  96          * This is the same as NWFPE, because it's not clear what
  97          * this is used for
  98          */
  99         current->thread.error_code = 0;
 100         current->thread.trap_no = 6;
 101
 102         send_sig_info(SIGFPE, &info, current);
 103 }
 104
 105 static void vfp_panic(char *reason)
 106 {
 107         int i;
 108
 109         printk(KERN_ERR "VFP: Error: %s\n", reason);
 110         printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
 111                 fmrx(FPEXC), fmrx(FPSCR), fmrx(FPINST));
 112         for (i = 0; i < 32; i += 2)
 113                 printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
 114                        i, vfp_get_float(i), i+1, vfp_get_float(i+1));
 115 }
 116
 117 /*
 118  * Process bitmask of exception conditions.
 119  */
 120 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
 121 {
 122         int si_code = 0;
 123
 124         pr_debug("VFP: raising exceptions %08x\n", exceptions);
 125
 126         if (exceptions == VFP_EXCEPTION_ERROR) {
 127                 vfp_panic("unhandled bounce");
 128                 vfp_raise_sigfpe(0, regs);
 129                 return;
 130         }
 131
 132         /*
 133          * If any of the status flags are set, update the FPSCR.
 134          * Comparison instructions always return at least one of
 135          * these flags set.
 136          */
 137         if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
 138                 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);
 139
 140         fpscr |= exceptions;
 141
 142         fmxr(FPSCR, fpscr);
 143
 144 #define RAISE(stat,en,sig)                              \
 145         if (exceptions & stat && fpscr & en)            \
 146                 si_code = sig;
 147
 148         /*
 149          * These are arranged in priority order, least to highest.
 150          */
 151         RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV);
 152         RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
 153         RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
 154         RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
 155         RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);
 156
 157         if (si_code)
 158                 vfp_raise_sigfpe(si_code, regs);
 159 }
 160
 161 /*
 162  * Emulate a VFP instruction.
 163  */
 164 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
 165 {
 166         u32 exceptions = VFP_EXCEPTION_ERROR;
 167
 168         pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);
 169
 170         if (INST_CPRTDO(inst)) {
 171                 if (!INST_CPRT(inst)) {
 172                         /*
 173                          * CPDO
 174                          */
 175                         if (vfp_single(inst)) {
 176                                 exceptions = vfp_single_cpdo(inst, fpscr);
 177                         } else {
 178                                 exceptions = vfp_double_cpdo(inst, fpscr);
 179                         }
 180                 } else {
 181                         /*
 182                          * A CPRT instruction can not appear in FPINST2, nor
 183                          * can it cause an exception.  Therefore, we do not
 184                          * have to emulate it.
 185                          */
 186                 }
 187         } else {
 188                 /*
 189                  * A CPDT instruction can not appear in FPINST2, nor can
 190                  * it cause an exception.  Therefore, we do not have to
 191                  * emulate it.
 192                  */
 193         }
 194         return exceptions & ~VFP_NAN_FLAG;
 195 }
 196
 197 /*
 198  * Package up a bounce condition.
 199  */
 200 void VFP9_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
 201 {
 202         u32 fpscr, orig_fpscr, exceptions, inst;
 203
 204         pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);
 205
 206         /*
 207          * Enable access to the VFP so we can handle the bounce.
 208          */
 209         fmxr(FPEXC, fpexc & ~(FPEXC_EXCEPTION|FPEXC_INV|FPEXC_UFC|FPEXC_IOC));
 210
 211         orig_fpscr = fpscr = fmrx(FPSCR);
 212
 213         /*
 214          * If we are running with inexact exceptions enabled, we need to
 215          * emulate the trigger instruction.  Note that as we're emulating
 216          * the trigger instruction, we need to increment PC.
 217          */
 218         if (fpscr & FPSCR_IXE) {
 219                 regs->ARM_pc += 4;
 220                 goto emulate;
 221         }
 222
 223         barrier();
 224
 225         /*
 226          * Modify fpscr to indicate the number of iterations remaining
 227          */
 228         if (fpexc & FPEXC_EXCEPTION) {
 229                 u32 len;
 230
 231                 len = fpexc + (1 << FPEXC_LENGTH_BIT);
 232
 233                 fpscr &= ~FPSCR_LENGTH_MASK;
 234                 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
 235         }
 236
 237         /*
 238          * Handle the first FP instruction.  We used to take note of the
 239          * FPEXC bounce reason, but this appears to be unreliable.
 240          * Emulate the bounced instruction instead.
 241          */
 242         inst = fmrx(FPINST);
 243         exceptions = vfp_emulate_instruction(inst, fpscr, regs);
 244         if (exceptions)
 245                 vfp_raise_exceptions(exceptions, inst, orig_fpscr, regs);
 246
 247         /*
 248          * If there isn't a second FP instruction, exit now.
 249          */
 250         if (!(fpexc & FPEXC_FPV2))
 251                 return;
 252
 253         /*
 254          * The barrier() here prevents fpinst2 being read
 255          * before the condition above.
 256          */
 257         barrier();
 258         trigger = fmrx(FPINST2);
 259         orig_fpscr = fpscr = fmrx(FPSCR);
 260
 261  emulate:
 262         exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
 263         if (exceptions)
 264                 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
 265 }
 266
 267 /*
 268  * VFP support code initialisation.
 269  */
 270 static int __init vfp_init(void)
 271 {
 272         unsigned int vfpsid;
 273
 274         /*
 275          * First check that there is a VFP that we can use.
 276          * The handler is already setup to just log calls, so
 277          * we just need to read the VFPSID register.
 278          */
 279         vfpsid = fmrx(FPSID);
 280
 281         printk(KERN_INFO "VFP support v0.3: ");
 282         if (VFP_arch) {
 283                 printk("not present\n");
 284         } else if (vfpsid & FPSID_NODOUBLE) {
 285                 printk("no double precision support\n");
 286         } else {
 287                 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;  /* Extract the architecture version */
 288                 printk("implementor %02x architecture %d part %02x variant %x rev %x\n",
 289                         (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
 290                         (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT,
 291                         (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
 292                         (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
 293                         (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);
 294                 vfp_vector = vfp_support_entry;
 295
 296                 thread_register_notifier(&vfp_notifier_block);
 297         }
 298         return 0;
 299 }
 300
 301 late_initcall(vfp_init);