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Sourcecode: linux-2.6 version File versions

vfpmodule.c

/*
 *  linux/arch/arm/vfp/vfpmodule.c
 *
 *  Copyright (C) 2004 ARM Limited.
 *  Written by Deep Blue Solutions Limited.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/init.h>

#include <asm/thread_notify.h>
#include <asm/vfp.h>

#include "vfpinstr.h"
#include "vfp.h"

/*
 * Our undef handlers (in entry.S)
 */
void vfp_testing_entry(void);
void vfp_support_entry(void);

void (*vfp_vector)(void) = vfp_testing_entry;
union vfp_state *last_VFP_context;

/*
 * Dual-use variable.
 * Used in startup: set to non-zero if VFP checks fail
 * After startup, holds VFP architecture
 */
unsigned int VFP_arch;

static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
{
      struct thread_info *thread = v;
      union vfp_state *vfp = &thread->vfpstate;

      switch (cmd) {
      case THREAD_NOTIFY_FLUSH:
            /*
             * Per-thread VFP initialisation.
             */
            memset(vfp, 0, sizeof(union vfp_state));

            vfp->hard.fpexc = FPEXC_ENABLE;
            vfp->hard.fpscr = FPSCR_ROUND_NEAREST;

            /*
             * Disable VFP to ensure we initialise it first.
             */
            fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);

            /*
             * FALLTHROUGH: Ensure we don't try to overwrite our newly
             * initialised state information on the first fault.
             */

      case THREAD_NOTIFY_RELEASE:
            /*
             * Per-thread VFP cleanup.
             */
            if (last_VFP_context == vfp)
                  last_VFP_context = NULL;
            break;

      case THREAD_NOTIFY_SWITCH:
            /*
             * Always disable VFP so we can lazily save/restore the
             * old state.
             */
            fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
            break;
      }

      return NOTIFY_DONE;
}

static struct notifier_block vfp_notifier_block = {
      .notifier_call    = vfp_notifier,
};

/*
 * Raise a SIGFPE for the current process.
 * sicode describes the signal being raised.
 */
void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
{
      siginfo_t info;

      memset(&info, 0, sizeof(info));

      info.si_signo = SIGFPE;
      info.si_code = sicode;
      info.si_addr = (void *)(instruction_pointer(regs) - 4);

      /*
       * This is the same as NWFPE, because it's not clear what
       * this is used for
       */
      current->thread.error_code = 0;
      current->thread.trap_no = 6;

      send_sig_info(SIGFPE, &info, current);
}

static void vfp_panic(char *reason)
{
      int i;

      printk(KERN_ERR "VFP: Error: %s\n", reason);
      printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
            fmrx(FPEXC), fmrx(FPSCR), fmrx(FPINST));
      for (i = 0; i < 32; i += 2)
            printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
                   i, vfp_get_float(i), i+1, vfp_get_float(i+1));
}

/*
 * Process bitmask of exception conditions.
 */
static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
{
      int si_code = 0;

      pr_debug("VFP: raising exceptions %08x\n", exceptions);

      if (exceptions == VFP_EXCEPTION_ERROR) {
            vfp_panic("unhandled bounce");
            vfp_raise_sigfpe(0, regs);
            return;
      }

      /*
       * If any of the status flags are set, update the FPSCR.
       * Comparison instructions always return at least one of
       * these flags set.
       */
      if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
            fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);

      fpscr |= exceptions;

      fmxr(FPSCR, fpscr);

#define RAISE(stat,en,sig)                      \
      if (exceptions & stat && fpscr & en)            \
            si_code = sig;

      /*
       * These are arranged in priority order, least to highest.
       */
      RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
      RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
      RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
      RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);

      if (si_code)
            vfp_raise_sigfpe(si_code, regs);
}

/*
 * Emulate a VFP instruction.
 */
static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
{
      u32 exceptions = VFP_EXCEPTION_ERROR;

      pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);

      if (INST_CPRTDO(inst)) {
            if (!INST_CPRT(inst)) {
                  /*
                   * CPDO
                   */
                  if (vfp_single(inst)) {
                        exceptions = vfp_single_cpdo(inst, fpscr);
                  } else {
                        exceptions = vfp_double_cpdo(inst, fpscr);
                  }
            } else {
                  /*
                   * A CPRT instruction can not appear in FPINST2, nor
                   * can it cause an exception.  Therefore, we do not
                   * have to emulate it.
                   */
            }
      } else {
            /*
             * A CPDT instruction can not appear in FPINST2, nor can
             * it cause an exception.  Therefore, we do not have to
             * emulate it.
             */
      }
      return exceptions & ~VFP_NAN_FLAG;
}

/*
 * Package up a bounce condition.
 */
void VFP9_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
{
      u32 fpscr, orig_fpscr, exceptions, inst;

      pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);

      /*
       * Enable access to the VFP so we can handle the bounce.
       */
      fmxr(FPEXC, fpexc & ~(FPEXC_EXCEPTION|FPEXC_INV|FPEXC_UFC|FPEXC_IOC));

      orig_fpscr = fpscr = fmrx(FPSCR);

      /*
       * If we are running with inexact exceptions enabled, we need to
       * emulate the trigger instruction.  Note that as we're emulating
       * the trigger instruction, we need to increment PC.
       */
      if (fpscr & FPSCR_IXE) {
            regs->ARM_pc += 4;
            goto emulate;
      }

      barrier();

      /*
       * Modify fpscr to indicate the number of iterations remaining
       */
      if (fpexc & FPEXC_EXCEPTION) {
            u32 len;

            len = fpexc + (1 << FPEXC_LENGTH_BIT);

            fpscr &= ~FPSCR_LENGTH_MASK;
            fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
      }

      /*
       * Handle the first FP instruction.  We used to take note of the
       * FPEXC bounce reason, but this appears to be unreliable.
       * Emulate the bounced instruction instead.
       */
      inst = fmrx(FPINST);
      exceptions = vfp_emulate_instruction(inst, fpscr, regs);
      if (exceptions)
            vfp_raise_exceptions(exceptions, inst, orig_fpscr, regs);

      /*
       * If there isn't a second FP instruction, exit now.
       */
      if (!(fpexc & FPEXC_FPV2))
            return;

      /*
       * The barrier() here prevents fpinst2 being read
       * before the condition above.
       */
      barrier();
      trigger = fmrx(FPINST2);
      orig_fpscr = fpscr = fmrx(FPSCR);

 emulate:
      exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
      if (exceptions)
            vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
}
 
/*
 * VFP support code initialisation.
 */
static int __init vfp_init(void)
{
      unsigned int vfpsid;

      /*
       * First check that there is a VFP that we can use.
       * The handler is already setup to just log calls, so
       * we just need to read the VFPSID register.
       */
      vfpsid = fmrx(FPSID);

      printk(KERN_INFO "VFP support v0.3: ");
      if (VFP_arch) {
            printk("not present\n");
      } else if (vfpsid & FPSID_NODOUBLE) {
            printk("no double precision support\n");
      } else {
            VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;  /* Extract the architecture version */
            printk("implementor %02x architecture %d part %02x variant %x rev %x\n",
                  (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
                  (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT,
                  (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
                  (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
                  (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);
            vfp_vector = vfp_support_entry;

            thread_register_notifier(&vfp_notifier_block);
      }
      return 0;
}

late_initcall(vfp_init);

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