Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $

 * fault.c:  Page fault handlers for the Sparc.

 *

 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)

 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)

 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)

 */

#include <asm/head.h>

#include <linux/string.h>

#include <linux/types.h>

#include <linux/sched.h>

#include <linux/ptrace.h>

#include <linux/mman.h>

#include <linux/threads.h>

#include <linux/kernel.h>

#include <linux/signal.h>

#include <linux/mm.h>

#include <linux/smp.h>

#include <linux/interrupt.h>

#include <linux/module.h>

#include <linux/kdebug.h>

#include <asm/system.h>

#include <asm/page.h>

#include <asm/pgtable.h>

#include <asm/memreg.h>

#include <asm/openprom.h>

#include <asm/oplib.h>

#include <asm/smp.h>

#include <asm/traps.h>

#include <asm/uaccess.h>

extern int prom_node_root;

/* At boot time we determine these two values necessary for setting

 * up the segment maps and page table entries (pte's).

 */

int num_segmaps, num_contexts;

int invalid_segment;

/* various Virtual Address Cache parameters we find at boot time... */

int vac_size, vac_linesize, vac_do_hw_vac_flushes;

int vac_entries_per_context, vac_entries_per_segment;

int vac_entries_per_page;

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

int prom_probe_memory (void)

{

        register struct linux_mlist_v0 *mlist;

        register unsigned long bytes, base_paddr, tally;

        register int i;

        i = 0;

        mlist= *prom_meminfo()->v0_available;

        bytes = tally = mlist->num_bytes;

        base_paddr = (unsigned long) 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 = (unsigned long) mlist->start_adr;

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

        }

        i++;

        sp_banks[i].base_addr = 0xdeadbeef;

        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;

}

/* Traverse the memory lists in the prom to see how much physical we

 * have.

 */

unsigned long

probe_memory(void)

{

        int total;

        total = prom_probe_memory();

        /* Oh man, much nicer, keep the dirt in promlib. */

        return total;

}

extern void sun4c_complete_all_stores(void);

/* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */

asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,

                                unsigned long svaddr, unsigned long aerr,

                                unsigned long avaddr)

{

        sun4c_complete_all_stores();

        printk("FAULT: NMI received\n");

        printk("SREGS: Synchronous Error %08lx\n", serr);

        printk("       Synchronous Vaddr %08lx\n", svaddr);

        printk("      Asynchronous Error %08lx\n", aerr);

        printk("      Asynchronous Vaddr %08lx\n", avaddr);

        if (sun4c_memerr_reg)

                printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);

        printk("REGISTER DUMP:\n");

        show_regs(regs);

        prom_halt();

}

static void unhandled_fault(unsigned long, struct task_struct *,

                struct pt_regs *) __attribute__ ((noreturn));

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 %08lx\n", address);

        }

        printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",

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

        printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",

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

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

        die_if_kernel("Oops", regs);

}

asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,

                            unsigned long address)

{

        struct pt_regs regs;

        unsigned long g2;

        unsigned int insn;

        int i;

        i = search_extables_range(ret_pc, &g2);

        switch (i) {

        case 3:

                /* load & store will be handled by fixup */

                return 3;

        case 1:

                /* store will be handled by fixup, load will bump out */

                /* for _to_ macros */

                insn = *((unsigned int *) pc);

                if ((insn >> 21) & 1)

                        return 1;

                break;

        case 2:

                /* load will be handled by fixup, store will bump out */

                /* for _from_ macros */

                insn = *((unsigned int *) pc);

                if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)

                        return 2;

                break;

        default:

                break;

        };

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

        regs.pc = pc;

        regs.npc = pc + 4;

        __asm__ __volatile__(

                "rd %%psr, %0\n\t"

                "nop\n\t"

                "nop\n\t"

                "nop\n" : "=r" (regs.psr));

        unhandled_fault(address, current, &regs);

        /* Not reached */

        return 0;

}

extern unsigned long safe_compute_effective_address(struct pt_regs *,

                                                    unsigned int);

static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)

{

        unsigned int insn;

        if (text_fault)

                return regs->pc;

        if (regs->psr & PSR_PS) {

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

        } else {

                __get_user(insn, (unsigned int *) regs->pc);

        }

        return safe_compute_effective_address(regs, insn);

}

asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,

                               unsigned long address)

{

        struct vm_area_struct *vma;

        struct task_struct *tsk = current;

        struct mm_struct *mm = tsk->mm;

        unsigned int fixup;

        unsigned long g2;

        siginfo_t info;

        int from_user = !(regs->psr & PSR_PS);

        int fault;

        if(text_fault)

                address = regs->pc;

        /*

         * We fault-in kernel-space virtual memory on-demand. The

         * 'reference' page table is init_mm.pgd.

         *

         * NOTE! We MUST NOT take any locks for this case. We may

         * be in an interrupt or a critical region, and should

         * only copy the information from the master page table,

         * nothing more.

         */

        if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)

                goto vmalloc_fault;

        info.si_code = SEGV_MAPERR;

        /*

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

         * context, we must not take the fault..

         */

        if (in_atomic() || !mm)

                goto no_context;

        down_read(&mm->mmap_sem);

        /*

         * The kernel referencing a bad kernel pointer can lock up

         * a sun4c machine completely, so we must attempt recovery.

         */

        if(!from_user && address >= PAGE_OFFSET)

                goto bad_area;

        vma = find_vma(mm, address);

        if(!vma)

                goto bad_area;

        if(vma->vm_start <= address)

                goto good_area;

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

                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:

        info.si_code = SEGV_ACCERR;

        if(write) {

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

                        goto bad_area;

        } else {

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

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

                        goto bad_area;

        }

        /*

         * If for any reason at all we couldn't handle the fault,

         * make sure we exit gracefully rather than endlessly redo

         * the fault.

         */

        fault = handle_mm_fault(mm, vma, address, write);

        if (unlikely(fault & VM_FAULT_ERROR)) {

                if (fault & VM_FAULT_OOM)

                        goto out_of_memory;

                else if (fault & VM_FAULT_SIGBUS)

                        goto do_sigbus;

                BUG();

        }

        if (fault & VM_FAULT_MAJOR)

                current->maj_flt++;

        else

                current->min_flt++;

        up_read(&mm->mmap_sem);

        return;

        /*

         * 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:

        up_read(&mm->mmap_sem);

bad_area_nosemaphore:

        /* User mode accesses just cause a SIGSEGV */

        if(from_user) {

#if 0

                printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",

                       tsk->comm, tsk->pid, address, regs->pc);

#endif

                info.si_signo = SIGSEGV;

                info.si_errno = 0;

                /* info.si_code set above to make clear whether

                   this was a SEGV_MAPERR or SEGV_ACCERR fault.  */

                info.si_addr = (void __user *)compute_si_addr(regs, text_fault);

                info.si_trapno = 0;

                force_sig_info (SIGSEGV, &info, tsk);

                return;

        }

        /* Is this in ex_table? */

no_context:

        g2 = regs->u_regs[UREG_G2];

        if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {

                if (fixup > 10) { /* Values below are reserved for other things */

                        extern const unsigned __memset_start[];

                        extern const unsigned __memset_end[];

                        extern const unsigned __csum_partial_copy_start[];

                        extern const unsigned __csum_partial_copy_end[];

#ifdef DEBUG_EXCEPTIONS

                        printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);

                        printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",

                                regs->pc, fixup, g2);

#endif

                        if ((regs->pc >= (unsigned long)__memset_start &&

                             regs->pc < (unsigned long)__memset_end) ||

                            (regs->pc >= (unsigned long)__csum_partial_copy_start &&

                             regs->pc < (unsigned long)__csum_partial_copy_end)) {

                                regs->u_regs[UREG_I4] = address;

                                regs->u_regs[UREG_I5] = regs->pc;

                        }

                        regs->u_regs[UREG_G2] = g2;

                        regs->pc = fixup;

                        regs->npc = regs->pc + 4;

                        return;

                }

        }

        unhandled_fault (address, tsk, regs);

        do_exit(SIGKILL);

/*

 * 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:

        up_read(&mm->mmap_sem);

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

        if (from_user)

                do_group_exit(SIGKILL);

        goto no_context;

do_sigbus:

        up_read(&mm->mmap_sem);

        info.si_signo = SIGBUS;

        info.si_errno = 0;

        info.si_code = BUS_ADRERR;

        info.si_addr = (void __user *) compute_si_addr(regs, text_fault);

        info.si_trapno = 0;

        force_sig_info (SIGBUS, &info, tsk);

        if (!from_user)

                goto no_context;

vmalloc_fault:

        {

                /*

                 * Synchronize this task's top level page-table

                 * with the 'reference' page table.

                 */

                int offset = pgd_index(address);

                pgd_t *pgd, *pgd_k;

                pmd_t *pmd, *pmd_k;

                pgd = tsk->active_mm->pgd + offset;

                pgd_k = init_mm.pgd + offset;

                if (!pgd_present(*pgd)) {

                        if (!pgd_present(*pgd_k))

                                goto bad_area_nosemaphore;

                        pgd_val(*pgd) = pgd_val(*pgd_k);

                        return;

                }

                pmd = pmd_offset(pgd, address);

                pmd_k = pmd_offset(pgd_k, address);

                if (pmd_present(*pmd) || !pmd_present(*pmd_k))

                        goto bad_area_nosemaphore;

                *pmd = *pmd_k;

                return;

        }

}

asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,

                               unsigned long address)

{

        extern void sun4c_update_mmu_cache(struct vm_area_struct *,

                                           unsigned long,pte_t);

        extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);

        struct task_struct *tsk = current;

        struct mm_struct *mm = tsk->mm;

        pgd_t *pgdp;

        pte_t *ptep;

        if (text_fault) {

                address = regs->pc;

        } else if (!write &&

                   !(regs->psr & PSR_PS)) {

                unsigned int insn, __user *ip;

                ip = (unsigned int __user *)regs->pc;

                if (!get_user(insn, ip)) {

                        if ((insn & 0xc1680000) == 0xc0680000)

                                write = 1;

                }

        }

        if (!mm) {

                /* We are oopsing. */

                do_sparc_fault(regs, text_fault, write, address);

                BUG();  /* P3 Oops already, you bitch */

        }

        pgdp = pgd_offset(mm, address);

        ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);

        if (pgd_val(*pgdp)) {

            if (write) {

                if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))

                                   == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {

                        unsigned long flags;

                        *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |

                                      _SUN4C_PAGE_MODIFIED |

                                      _SUN4C_PAGE_VALID |

                                      _SUN4C_PAGE_DIRTY);

                        local_irq_save(flags);

                        if (sun4c_get_segmap(address) != invalid_segment) {

                                sun4c_put_pte(address, pte_val(*ptep));

                                local_irq_restore(flags);

                                return;

                        }

                        local_irq_restore(flags);

                }

            } else {

                if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))

                                   == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {

                        unsigned long flags;

                        *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |

                                      _SUN4C_PAGE_VALID);

                        local_irq_save(flags);

                        if (sun4c_get_segmap(address) != invalid_segment) {

                                sun4c_put_pte(address, pte_val(*ptep));

                                local_irq_restore(flags);

                                return;

                        }

                        local_irq_restore(flags);

                }

            }

        }

        /* This conditional is 'interesting'. */

        if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))

            && (pte_val(*ptep) & _SUN4C_PAGE_VALID))

                /* Note: It is safe to not grab the MMAP semaphore here because

                 *       we know that update_mmu_cache() will not sleep for

                 *       any reason (at least not in the current implementation)

                 *       and therefore there is no danger of another thread getting

                 *       on the CPU and doing a shrink_mmap() on this vma.

                 */

                sun4c_update_mmu_cache (find_vma(current->mm, address), address,

                                        *ptep);

        else

                do_sparc_fault(regs, text_fault, write, address);

}

/* This always deals with user addresses. */

inline void force_user_fault(unsigned long address, int write)

{

        struct vm_area_struct *vma;

        struct task_struct *tsk = current;

        struct mm_struct *mm = tsk->mm;

        siginfo_t info;

        info.si_code = SEGV_MAPERR;

#if 0

        printk("wf<pid=%d,wr=%d,addr=%08lx>\n",

               tsk->pid, write, address);

#endif

        down_read(&mm->mmap_sem);

        vma = find_vma(mm, address);

        if(!vma)

                goto bad_area;

        if(vma->vm_start <= address)

                goto good_area;

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

                goto bad_area;

        if(expand_stack(vma, address))

                goto bad_area;

good_area:

        info.si_code = SEGV_ACCERR;

        if(write) {

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

                        goto bad_area;

        } else {

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

                        goto bad_area;

        }

        switch (handle_mm_fault(mm, vma, address, write)) {

        case VM_FAULT_SIGBUS:

        case VM_FAULT_OOM:

                goto do_sigbus;

        }

        up_read(&mm->mmap_sem);

        return;

bad_area:

        up_read(&mm->mmap_sem);

#if 0

        printk("Window whee %s [%d]: segfaults at %08lx\n",

               tsk->comm, tsk->pid, address);

#endif

        info.si_signo = SIGSEGV;

        info.si_errno = 0;

        /* info.si_code set above to make clear whether

           this was a SEGV_MAPERR or SEGV_ACCERR fault.  */

        info.si_addr = (void __user *) address;

        info.si_trapno = 0;

        force_sig_info (SIGSEGV, &info, tsk);

        return;

do_sigbus:

        up_read(&mm->mmap_sem);

        info.si_signo = SIGBUS;

        info.si_errno = 0;

        info.si_code = BUS_ADRERR;

        info.si_addr = (void __user *) address;

        info.si_trapno = 0;

        force_sig_info (SIGBUS, &info, tsk);

}

void window_overflow_fault(void)

{

        unsigned long sp;

        sp = current_thread_info()->rwbuf_stkptrs[0];

        if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))

                force_user_fault(sp + 0x38, 1);

        force_user_fault(sp, 1);

}

void window_underflow_fault(unsigned long sp)

{

        if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))

                force_user_fault(sp + 0x38, 0);

        force_user_fault(sp, 0);

}

void window_ret_fault(struct pt_regs *regs)

{

        unsigned long sp;

        sp = regs->u_regs[UREG_FP];

        if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))

                force_user_fault(sp + 0x38, 0);

        force_user_fault(sp, 0);

}