softemu8xx.c

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/*
 * Software emulation of some PPC instructions for the 8xx core.
 *
 * Copyright (C) 1998 Dan Malek ([email protected])
 *
 * Software floating emuation for the MPC8xx processor.  I did this mostly
 * because it was easier than trying to get the libraries compiled for
 * software floating point.  The goal is still to get the libraries done,
 * but I lost patience and needed some hacks to at least get init and
 * shells running.  The first problem is the setjmp/longjmp that save
 * and restore the floating point registers.
 *
 * For this emulation, our working registers are found on the register
 * save area.
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/interrupt.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/io.h>

/* Eventually we may need a look-up table, but this works for now.
*/
#define LFS 48
#define LFD 50
#define LFDU    51
#define STFD    54
#define STFDU   55
#define FMR 63

void print_8xx_pte(struct mm_struct *mm, unsigned long addr)
{
    pgd_t *pgd;
    pmd_t *pmd;
    pte_t *pte;

    printk(" pte @ 0x%8lx: ", addr);
    pgd = pgd_offset(mm, addr & PAGE_MASK);
    if (pgd) {
        pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
                         addr & PAGE_MASK);
        if (pmd && pmd_present(*pmd)) {
            pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
            if (pte) {
                printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",
                        (long)pgd, (long)pte, (long)pte_val(*pte));
#define pp ((long)pte_val(*pte))
                printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "
                       "CI: %lx v: %lx\n",
                       pp>>12,    /* rpn */
                       (pp>>10)&3, /* pp */
                       (pp>>3)&1, /* small */
                       (pp>>2)&1, /* shared */
                       (pp>>1)&1, /* cache inhibit */
                       pp&1       /* valid */
                       );
#undef pp
            }
            else {
                printk("no pte\n");
            }
        }
        else {
            printk("no pmd\n");
        }
    }
    else {
        printk("no pgd\n");
    }
}

int get_8xx_pte(struct mm_struct *mm, unsigned long addr)
{
    pgd_t *pgd;
    pmd_t *pmd;
    pte_t *pte;
    int retval = 0;

    pgd = pgd_offset(mm, addr & PAGE_MASK);
    if (pgd) {
        pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),
                         addr & PAGE_MASK);
        if (pmd && pmd_present(*pmd)) {
            pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
            if (pte) {
                retval = (int)pte_val(*pte);
            }
        }
    }
    return retval;
}

/*
 * We return 0 on success, 1 on unimplemented instruction, and EFAULT
 * if a load/store faulted.
 */
int Soft_emulate_8xx(struct pt_regs *regs)
{
    u32 inst, instword;
    u32 flreg, idxreg, disp;
    int retval;
    s16 sdisp;
    u32 *ea, *ip;

    retval = 0;

    instword = *((u32 *)regs->nip);
    inst = instword >> 26;

    flreg = (instword >> 21) & 0x1f;
    idxreg = (instword >> 16) & 0x1f;
    disp = instword & 0xffff;

    ea = (u32 *)(regs->gpr[idxreg] + disp);
    ip = (u32 *)&current->thread.TS_FPR(flreg);

    switch ( inst )
    {
    case LFD:
        /* this is a 16 bit quantity that is sign extended
         * so use a signed short here -- Cort
         */
        sdisp = (instword & 0xffff);
        ea = (u32 *)(regs->gpr[idxreg] + sdisp);
        if (copy_from_user(ip, ea, sizeof(double)))
            retval = -EFAULT;
        break;

    case LFDU:
        if (copy_from_user(ip, ea, sizeof(double)))
            retval = -EFAULT;
        else
            regs->gpr[idxreg] = (u32)ea;
        break;
    case LFS:
        sdisp = (instword & 0xffff);
        ea = (u32 *)(regs->gpr[idxreg] + sdisp);
        if (copy_from_user(ip, ea, sizeof(float)))
            retval = -EFAULT;
        break;
    case STFD:
        /* this is a 16 bit quantity that is sign extended
         * so use a signed short here -- Cort
         */
        sdisp = (instword & 0xffff);
        ea = (u32 *)(regs->gpr[idxreg] + sdisp);
        if (copy_to_user(ea, ip, sizeof(double)))
            retval = -EFAULT;
        break;

    case STFDU:
        if (copy_to_user(ea, ip, sizeof(double)))
            retval = -EFAULT;
        else
            regs->gpr[idxreg] = (u32)ea;
        break;
    case FMR:
        /* assume this is a fp move -- Cort */
        memcpy(ip, &current->thread.TS_FPR((instword>>11)&0x1f),
               sizeof(double));
        break;
    default:
        retval = 1;
        printk("Bad emulation %s/%d\n"
               " NIP: %08lx instruction: %08x opcode: %x "
               "A: %x B: %x C: %x code: %x rc: %x\n",
               current->comm,current->pid,
               regs->nip,
               instword,inst,
               (instword>>16)&0x1f,
               (instword>>11)&0x1f,
               (instword>>6)&0x1f,
               (instword>>1)&0x3ff,
               instword&1);
        {
            int pa;
            print_8xx_pte(current->mm,regs->nip);
            pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;
            pa |= (regs->nip & ~PAGE_MASK);
            pa = (unsigned long)__va(pa);
            printk("Kernel VA for NIP %x ", pa);
            print_8xx_pte(current->mm,pa);
        }
    }

    if (retval == 0)
        regs->nip += 4;

    return retval;
}