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/* $Id: fault.c,v 1.1.1.1 2004-04-15 01:33:38 phoenix Exp $

 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.

 *

 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)

 * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)

 */

#include <asm/head.h>

#include <linux/string.h>

#include <linux/types.h>

#include <linux/ptrace.h>

#include <linux/mman.h>

#include <linux/signal.h>

#include <linux/mm.h>

#include <linux/smp_lock.h>

#include <linux/init.h>

#include <linux/interrupt.h>

#include <asm/page.h>

#include <asm/pgtable.h>

#include <asm/openprom.h>

#include <asm/oplib.h>

#include <asm/uaccess.h>

#include <asm/asi.h>

#include <asm/lsu.h>

#define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))

extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];

/*

 * To debug kernel during syscall entry.

 */

void syscall_trace_entry(struct pt_regs *regs)

{

        printk("scall entry: %s[%d]/cpu%d: %d\n", current->comm, current->pid, smp_processor_id(), (int) regs->u_regs[UREG_G1]);

}

/*

 * To debug kernel during syscall exit.

 */

void syscall_trace_exit(struct pt_regs *regs)

{

        printk("scall exit: %s[%d]/cpu%d: %d\n", current->comm, current->pid, smp_processor_id(), (int) regs->u_regs[UREG_G1]);

}

/*

 * To debug kernel to catch accesses to certain virtual/physical addresses.

 * Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.

 * flags = VM_READ watches memread accesses, flags = VM_WRITE watches memwrite accesses.

 * Caller passes in a 64bit aligned addr, with mask set to the bytes that need to be

 * watched. This is only useful on a single cpu machine for now. After the watchpoint

 * is detected, the process causing it will be killed, thus preventing an infinite loop.

 */

void set_brkpt(unsigned long addr, unsigned char mask, int flags, int mode)

{

        unsigned long lsubits;

        __asm__ __volatile__("ldxa [%%g0] %1, %0"

                             : "=r" (lsubits)

                             : "i" (ASI_LSU_CONTROL));

        lsubits &= ~(LSU_CONTROL_PM | LSU_CONTROL_VM |

                     LSU_CONTROL_PR | LSU_CONTROL_VR |

                     LSU_CONTROL_PW | LSU_CONTROL_VW);

        __asm__ __volatile__("stxa      %0, [%1] %2\n\t"

                             "membar    #Sync"

                             : /* no outputs */

                             : "r" (addr), "r" (mode ? VIRT_WATCHPOINT : PHYS_WATCHPOINT),

                               "i" (ASI_DMMU));

        lsubits |= ((unsigned long)mask << (mode ? 25 : 33));

        if (flags & VM_READ)

                lsubits |= (mode ? LSU_CONTROL_VR : LSU_CONTROL_PR);

        if (flags & VM_WRITE)

                lsubits |= (mode ? LSU_CONTROL_VW : LSU_CONTROL_PW);

        __asm__ __volatile__("stxa %0, [%%g0] %1\n\t"

                             "membar #Sync"

                             : /* no outputs */

                             : "r" (lsubits), "i" (ASI_LSU_CONTROL)

                             : "memory");

}

/* Nice, simple, prom library does all the sweating for us. ;) */

unsigned long __init prom_probe_memory (void)

{

        register struct linux_mlist_p1275 *mlist;

        register unsigned long bytes, base_paddr, tally;

        register int i;

        i = 0;

        mlist = *prom_meminfo()->p1275_available;

        bytes = tally = mlist->num_bytes;

        base_paddr = mlist->start_adr;

        sp_banks[0].base_addr = base_paddr;

        sp_banks[0].num_bytes = bytes;

        while (mlist->theres_more != (void *) 0) {

                i++;

                mlist = mlist->theres_more;

                bytes = mlist->num_bytes;

                tally += bytes;

                if (i >= SPARC_PHYS_BANKS-1) {

                        printk ("The machine has more banks than "

                                "this kernel can support\n"

                                "Increase the SPARC_PHYS_BANKS "

                                "setting (currently %d)\n",

                                SPARC_PHYS_BANKS);

                        i = SPARC_PHYS_BANKS-1;

                        break;

                }

                sp_banks[i].base_addr = mlist->start_adr;

                sp_banks[i].num_bytes = mlist->num_bytes;

        }

        i++;

        sp_banks[i].base_addr = 0xdeadbeefbeefdeadUL;

        sp_banks[i].num_bytes = 0;

        /* Now mask all bank sizes on a page boundary, it is all we can

         * use anyways.

         */

        for (i = 0; sp_banks[i].num_bytes != 0; i++)

                sp_banks[i].num_bytes &= PAGE_MASK;

        return tally;

}

static void unhandled_fault(unsigned long address, struct task_struct *tsk,

                            struct pt_regs *regs)

{

        if ((unsigned long) address < PAGE_SIZE) {

                printk(KERN_ALERT "Unable to handle kernel NULL "

                       "pointer dereference\n");

        } else {

                printk(KERN_ALERT "Unable to handle kernel paging request "

                       "at virtual address %016lx\n", (unsigned long)address);

        }

        printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",

               (tsk->mm ? tsk->mm->context : tsk->active_mm->context));

        printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",

               (tsk->mm ? (unsigned long) tsk->mm->pgd :

                          (unsigned long) tsk->active_mm->pgd));

        die_if_kernel("Oops", regs);

}

extern void show_trace_raw(struct task_struct *, unsigned long);

static void bad_kernel_pc(struct pt_regs *regs)

{

        unsigned long ksp;

        printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",

               regs->tpc);

        __asm__("mov %%sp, %0" : "=r" (ksp));

        show_trace_raw(current, ksp);

        unhandled_fault(regs->tpc, current, regs);

}

/*

 * We now make sure that mmap_sem is held in all paths that call

 * this. Additionally, to prevent kswapd from ripping ptes from

 * under us, raise interrupts around the time that we look at the

 * pte, kswapd will have to wait to get his smp ipi response from

 * us. This saves us having to get page_table_lock.

 */

static unsigned int get_user_insn(unsigned long tpc)

{

        pgd_t *pgdp = pgd_offset(current->mm, tpc);

        pmd_t *pmdp;

        pte_t *ptep, pte;

        unsigned long pa;

        u32 insn = 0;

        unsigned long pstate;

        if (pgd_none(*pgdp))

                goto outret;

        pmdp = pmd_offset(pgdp, tpc);

        if (pmd_none(*pmdp))

                goto outret;

        ptep = pte_offset(pmdp, tpc);

        __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));

        __asm__ __volatile__("wrpr %0, %1, %%pstate"

                                : : "r" (pstate), "i" (PSTATE_IE));

        pte = *ptep;

        if (!pte_present(pte))

                goto out;

        pa  = (pte_val(pte) & _PAGE_PADDR);

        pa += (tpc & ~PAGE_MASK);

        /* Use phys bypass so we don't pollute dtlb/dcache. */

        __asm__ __volatile__("lduwa [%1] %2, %0"

                             : "=r" (insn)

                             : "r" (pa), "i" (ASI_PHYS_USE_EC));

out:

        __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));

outret:

        return insn;

}

static void do_fault_siginfo(int code, int sig, unsigned long address)

{

        siginfo_t info;

        info.si_code = code;

        info.si_signo = sig;

        info.si_errno = 0;

        info.si_addr = (void *) address;

        info.si_trapno = 0;

        force_sig_info(sig, &info, current);

}

extern int handle_ldf_stq(u32, struct pt_regs *);

extern int handle_ld_nf(u32, struct pt_regs *);

static inline unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)

{

        if (!insn) {

                if (!regs->tpc || (regs->tpc & 0x3))

                        return 0;

                if (regs->tstate & TSTATE_PRIV) {

                        insn = *(unsigned int *) regs->tpc;

                } else {

                        insn = get_user_insn(regs->tpc);

                }

        }

        return insn;

}

static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,

                            unsigned int insn, unsigned long address)

{

        unsigned long g2;

        unsigned char asi = ASI_P;

        if ((!insn) && (regs->tstate & TSTATE_PRIV))

                goto cannot_handle;

        /* If user insn could be read (thus insn is zero), that

         * is fine.  We will just gun down the process with a signal

         * in that case.

         */

        if (!(fault_code & FAULT_CODE_WRITE) &&

            (insn & 0xc0800000) == 0xc0800000) {

                if (insn & 0x2000)

                        asi = (regs->tstate >> 24);

                else

                        asi = (insn >> 5);

                if ((asi & 0xf2) == 0x82) {

                        if (insn & 0x1000000) {

                                handle_ldf_stq(insn, regs);

                        } else {

                                /* This was a non-faulting load. Just clear the

                                 * destination register(s) and continue with the next

                                 * instruction. -jj

                                 */

                                handle_ld_nf(insn, regs);

                        }

                        return;

                }

        }

        g2 = regs->u_regs[UREG_G2];

        /* Is this in ex_table? */

        if (regs->tstate & TSTATE_PRIV) {

                unsigned long fixup;

                if (asi == ASI_P && (insn & 0xc0800000) == 0xc0800000) {

                        if (insn & 0x2000)

                                asi = (regs->tstate >> 24);

                        else

                                asi = (insn >> 5);

                }

                /* Look in asi.h: All _S asis have LS bit set */

                if ((asi & 0x1) &&

                    (fixup = search_exception_table (regs->tpc, &g2))) {

                        regs->tpc = fixup;

                        regs->tnpc = regs->tpc + 4;

                        regs->u_regs[UREG_G2] = g2;

                        return;

                }

        } else {

                /* The si_code was set to make clear whether

                 * this was a SEGV_MAPERR or SEGV_ACCERR fault.

                 */

                do_fault_siginfo(si_code, SIGSEGV, address);

                return;

        }

cannot_handle:

        unhandled_fault (address, current, regs);

}

asmlinkage void do_sparc64_fault(struct pt_regs *regs)

{

        struct mm_struct *mm = current->mm;

        struct vm_area_struct *vma;

        unsigned int insn = 0;

        int si_code, fault_code;

        unsigned long address;

        si_code = SEGV_MAPERR;

        fault_code = current->thread.fault_code;

        address = current->thread.fault_address;

        if ((fault_code & FAULT_CODE_ITLB) &&

            (fault_code & FAULT_CODE_DTLB))

                BUG();

        if (regs->tstate & TSTATE_PRIV) {

                unsigned long tpc = regs->tpc;

                extern unsigned int _etext;

                /* Sanity check the PC. */

                if ((tpc >= KERNBASE && tpc < (unsigned long) &_etext) ||

                    (tpc >= MODULES_VADDR && tpc < MODULES_END)) {

                        /* Valid, no problems... */

                } else {

                        bad_kernel_pc(regs);

                        return;

                }

        }

        /*

         * If we're in an interrupt or have no user

         * context, we must not take the fault..

         */

        if (in_interrupt() || !mm)

                goto intr_or_no_mm;

        if ((current->thread.flags & SPARC_FLAG_32BIT) != 0) {

                regs->tpc &= 0xffffffff;

                address &= 0xffffffff;

        }

        down_read(&mm->mmap_sem);

        vma = find_vma(mm, address);

        if (!vma)

                goto bad_area;

        /* Pure DTLB misses do not tell us whether the fault causing

         * load/store/atomic was a write or not, it only says that there

         * was no match.  So in such a case we (carefully) read the

         * instruction to try and figure this out.  It's an optimization

         * so it's ok if we can't do this.

         *

         * Special hack, window spill/fill knows the exact fault type.

         */

        if (((fault_code &

              (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&

            (vma->vm_flags & VM_WRITE) != 0) {

                insn = get_fault_insn(regs, 0);

                if (!insn)

                        goto continue_fault;

                if ((insn & 0xc0200000) == 0xc0200000 &&

                    (insn & 0x1780000) != 0x1680000) {

                        /* Don't bother updating thread struct value,

                         * because update_mmu_cache only cares which tlb

                         * the access came from.

                         */

                        fault_code |= FAULT_CODE_WRITE;

                }

        }

continue_fault:

        if (vma->vm_start <= address)

                goto good_area;

        if (!(vma->vm_flags & VM_GROWSDOWN))

                goto bad_area;

        if (!(fault_code & FAULT_CODE_WRITE)) {

                /* Non-faulting loads shouldn't expand stack. */

                insn = get_fault_insn(regs, insn);

                if ((insn & 0xc0800000) == 0xc0800000) {

                        unsigned char asi;

                        if (insn & 0x2000)

                                asi = (regs->tstate >> 24);

                        else

                                asi = (insn >> 5);

                        if ((asi & 0xf2) == 0x82)

                                goto bad_area;

                }

        }

        if (expand_stack(vma, address))

                goto bad_area;

        /*

         * Ok, we have a good vm_area for this memory access, so

         * we can handle it..

         */

good_area:

        si_code = SEGV_ACCERR;

        if (fault_code & FAULT_CODE_WRITE) {

                if (!(vma->vm_flags & VM_WRITE))

                        goto bad_area;

                /* Spitfire has an icache which does not snoop

                 * processor stores.  Later processors do...

                 */

                if (tlb_type == spitfire &&

                    (vma->vm_flags & VM_EXEC) != 0 &&

                    vma->vm_file != NULL)

                        current->thread.use_blkcommit = 1;

        } else {

                /* Allow reads even for write-only mappings */

                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))

                        goto bad_area;

        }

        switch (handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE))) {

        case 1:

                current->min_flt++;

                break;

        case 2:

                current->maj_flt++;

                break;

        case 0:

                goto do_sigbus;

        default:

                goto out_of_memory;

        }

        up_read(&mm->mmap_sem);

        goto fault_done;

        /*

         * Something tried to access memory that isn't in our memory map..

         * Fix it, but check if it's kernel or user first..

         */

bad_area:

        insn = get_fault_insn(regs, insn);

        up_read(&mm->mmap_sem);

handle_kernel_fault:

        do_kernel_fault(regs, si_code, fault_code, insn, address);

        goto fault_done;

/*

 * We ran out of memory, or some other thing happened to us that made

 * us unable to handle the page fault gracefully.

 */

out_of_memory:

        insn = get_fault_insn(regs, insn);

        up_read(&mm->mmap_sem);

        printk("VM: killing process %s\n", current->comm);

        if (!(regs->tstate & TSTATE_PRIV))

                do_exit(SIGKILL);

        goto handle_kernel_fault;

intr_or_no_mm:

        insn = get_fault_insn(regs, 0);

        goto handle_kernel_fault;

do_sigbus:

        insn = get_fault_insn(regs, insn);

        up_read(&mm->mmap_sem);

        /*

         * Send a sigbus, regardless of whether we were in kernel

         * or user mode.

         */

        do_fault_siginfo(BUS_ADRERR, SIGBUS, address);

        /* Kernel mode? Handle exceptions or die */

        if (regs->tstate & TSTATE_PRIV)

                goto handle_kernel_fault;

fault_done:

        /* These values are no longer needed, clear them. */

        current->thread.fault_code = 0;

        current->thread.use_blkcommit = 0;

        current->thread.fault_address = 0;

}