LXR linux/arch/unicore32/kernel/fpu-ucf64.c

   1/*
   2 * linux/arch/unicore32/kernel/fpu-ucf64.c
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 * Copyright (C) 2001-2010 GUAN Xue-tao
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12#include <linux/module.h>
  13#include <linux/types.h>
  14#include <linux/kernel.h>
  15#include <linux/signal.h>
  16#include <linux/sched.h>
  17#include <linux/init.h>
  18
  19#include <asm/fpu-ucf64.h>
  20
  21/*
  22 * A special flag to tell the normalisation code not to normalise.
  23 */
  24#define F64_NAN_FLAG    0x100
  25
  26/*
  27 * A bit pattern used to indicate the initial (unset) value of the
  28 * exception mask, in case nothing handles an instruction.  This
  29 * doesn't include the NAN flag, which get masked out before
  30 * we check for an error.
  31 */
  32#define F64_EXCEPTION_ERROR     ((u32)-1 & ~F64_NAN_FLAG)
  33
  34/*
  35 * Since we aren't building with -mfpu=f64, we need to code
  36 * these instructions using their MRC/MCR equivalents.
  37 */
  38#define f64reg(_f64_) #_f64_
  39
  40#define cff(_f64_) ({                   \
  41        u32 __v;                        \
  42        asm("cff %0, " f64reg(_f64_) "@ fmrx    %0, " #_f64_    \
  43            : "=r" (__v) : : "cc");     \
  44        __v;                            \
  45        })
  46
  47#define ctf(_f64_, _var_)               \
  48        asm("ctf %0, " f64reg(_f64_) "@ fmxr    " #_f64_ ", %0" \
  49           : : "r" (_var_) : "cc")
  50
  51/*
  52 * Raise a SIGFPE for the current process.
  53 * sicode describes the signal being raised.
  54 */
  55void ucf64_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
  56{
  57        siginfo_t info;
  58
  59        memset(&info, 0, sizeof(info));
  60
  61        info.si_signo = SIGFPE;
  62        info.si_code = sicode;
  63        info.si_addr = (void __user *)(instruction_pointer(regs) - 4);
  64
  65        /*
  66         * This is the same as NWFPE, because it's not clear what
  67         * this is used for
  68         */
  69        current->thread.error_code = 0;
  70        current->thread.trap_no = 6;
  71
  72        send_sig_info(SIGFPE, &info, current);
  73}
  74
  75/*
  76 * Handle exceptions of UniCore-F64.
  77 */
  78void ucf64_exchandler(u32 inst, u32 fpexc, struct pt_regs *regs)
  79{
  80        u32 tmp = fpexc;
  81        u32 exc = F64_EXCEPTION_ERROR & fpexc;
  82
  83        pr_debug("UniCore-F64: instruction %08x fpscr %08x\n",
  84                        inst, fpexc);
  85
  86        if (exc & FPSCR_CMPINSTR_BIT) {
  87                if (exc & FPSCR_CON)
  88                        tmp |= FPSCR_CON;
  89                else
  90                        tmp &= ~(FPSCR_CON);
  91                exc &= ~(FPSCR_CMPINSTR_BIT | FPSCR_CON);
  92        } else {
  93                pr_debug(KERN_ERR "UniCore-F64 Error: unhandled exceptions\n");
  94                pr_debug(KERN_ERR "UniCore-F64 FPSCR 0x%08x INST 0x%08x\n",
  95                                cff(FPSCR), inst);
  96
  97                ucf64_raise_sigfpe(0, regs);
  98                return;
  99        }
 100
 101        /*
 102         * Update the FPSCR with the additional exception flags.
 103         * Comparison instructions always return at least one of
 104         * these flags set.
 105         */
 106        tmp &= ~(FPSCR_TRAP | FPSCR_IOS | FPSCR_OFS | FPSCR_UFS |
 107                        FPSCR_IXS | FPSCR_HIS | FPSCR_IOC | FPSCR_OFC |
 108                        FPSCR_UFC | FPSCR_IXC | FPSCR_HIC);
 109
 110        tmp |= exc;
 111        ctf(FPSCR, tmp);
 112}
 113
 114/*
 115 * F64 support code initialisation.
 116 */
 117static int __init ucf64_init(void)
 118{
 119        ctf(FPSCR, 0x0);     /* FPSCR_UFE | FPSCR_NDE perhaps better */
 120
 121        printk(KERN_INFO "Enable UniCore-F64 support.\n");
 122
 123        return 0;
 124}
 125
 126late_initcall(ucf64_init);
 127