1 files changed, 440 insertions, 0 deletions

diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c
new file mode 100644
index 000000000000..57d9930843ac
--- /dev/null
+++ b/arch/ppc/mm/fault.c
@@ -0,0 +1,440 @@
+/*
+ *  arch/ppc/mm/fault.c
+ *
+ *  PowerPC version
+ *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ *  Derived from "arch/i386/mm/fault.c"
+ *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  Modified by Cort Dougan and Paul Mackerras.
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version
+ *  2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/tlbflush.h>
+
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+extern void (*debugger)(struct pt_regs *);
+extern void (*debugger_fault_handler)(struct pt_regs *);
+extern int (*debugger_dabr_match)(struct pt_regs *);
+int debugger_kernel_faults = 1;
+#endif
+
+unsigned long htab_reloads;     /* updated by hashtable.S:hash_page() */
+unsigned long htab_evicts;      /* updated by hashtable.S:hash_page() */
+unsigned long htab_preloads;    /* updated by hashtable.S:add_hash_page() */
+unsigned long pte_misses;       /* updated by do_page_fault() */
+unsigned long pte_errors;       /* updated by do_page_fault() */
+unsigned int probingmem;
+
+/*
+ * Check whether the instruction at regs->nip is a store using
+ * an update addressing form which will update r1.
+ */
+static int store_updates_sp(struct pt_regs *regs)
+{
+        unsigned int inst;
+
+        if (get_user(inst, (unsigned int __user *)regs->nip))
+                return 0;
+        /* check for 1 in the rA field */
+        if (((inst >> 16) & 0x1f) != 1)
+                return 0;
+        /* check major opcode */
+        switch (inst >> 26) {
+        case 37:        /* stwu */
+        case 39:        /* stbu */
+        case 45:        /* sthu */
+        case 53:        /* stfsu */
+        case 55:        /* stfdu */
+                return 1;
+        case 31:
+                /* check minor opcode */
+                switch ((inst >> 1) & 0x3ff) {
+                case 183:       /* stwux */
+                case 247:       /* stbux */
+                case 439:       /* sthux */
+                case 695:       /* stfsux */
+                case 759:       /* stfdux */
+                        return 1;
+                }
+        }
+        return 0;
+}
+
+/*
+ * For 600- and 800-family processors, the error_code parameter is DSISR
+ * for a data fault, SRR1 for an instruction fault. For 400-family processors
+ * the error_code parameter is ESR for a data fault, 0 for an instruction
+ * fault.
+ */
+int do_page_fault(struct pt_regs *regs, unsigned long address,
+                  unsigned long error_code)
+{
+        struct vm_area_struct * vma;
+        struct mm_struct *mm = current->mm;
+        siginfo_t info;
+        int code = SEGV_MAPERR;
+#if defined(CONFIG_4xx) || defined (CONFIG_BOOKE)
+        int is_write = error_code & ESR_DST;
+#else
+        int is_write = 0;
+
+        /*
+         * Fortunately the bit assignments in SRR1 for an instruction
+         * fault and DSISR for a data fault are mostly the same for the
+         * bits we are interested in.  But there are some bits which
+         * indicate errors in DSISR but can validly be set in SRR1.
+         */
+        if (TRAP(regs) == 0x400)
+                error_code &= 0x48200000;
+        else
+                is_write = error_code & 0x02000000;
+#endif /* CONFIG_4xx || CONFIG_BOOKE */
+
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+        if (debugger_fault_handler && TRAP(regs) == 0x300) {
+                debugger_fault_handler(regs);
+                return 0;
+        }
+#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
+        if (error_code & 0x00400000) {
+                /* DABR match */
+                if (debugger_dabr_match(regs))
+                        return 0;
+        }
+#endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/
+#endif /* CONFIG_XMON || CONFIG_KGDB */
+
+        if (in_atomic() || mm == NULL)
+                return SIGSEGV;
+
+        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 (!is_write)
+                goto bad_area;
+
+        /*
+         * N.B. The rs6000/xcoff ABI allows programs to access up to
+         * a few hundred bytes below the stack pointer.
+         * The kernel signal delivery code writes up to about 1.5kB
+         * below the stack pointer (r1) before decrementing it.
+         * The exec code can write slightly over 640kB to the stack
+         * before setting the user r1.  Thus we allow the stack to
+         * expand to 1MB without further checks.
+         */
+        if (address + 0x100000 < vma->vm_end) {
+                /* get user regs even if this fault is in kernel mode */
+                struct pt_regs *uregs = current->thread.regs;
+                if (uregs == NULL)
+                        goto bad_area;
+
+                /*
+                 * A user-mode access to an address a long way below
+                 * the stack pointer is only valid if the instruction
+                 * is one which would update the stack pointer to the
+                 * address accessed if the instruction completed,
+                 * i.e. either stwu rs,n(r1) or stwux rs,r1,rb
+                 * (or the byte, halfword, float or double forms).
+                 *
+                 * If we don't check this then any write to the area
+                 * between the last mapped region and the stack will
+                 * expand the stack rather than segfaulting.
+                 */
+                if (address + 2048 < uregs->gpr[1]
+                    && (!user_mode(regs) || !store_updates_sp(regs)))
+                        goto bad_area;
+        }
+        if (expand_stack(vma, address))
+                goto bad_area;
+
+good_area:
+        code = SEGV_ACCERR;
+#if defined(CONFIG_6xx)
+        if (error_code & 0x95700000)
+                /* an error such as lwarx to I/O controller space,
+                   address matching DABR, eciwx, etc. */
+                goto bad_area;
+#endif /* CONFIG_6xx */
+#if defined(CONFIG_8xx)
+        /* The MPC8xx seems to always set 0x80000000, which is
+         * "undefined".  Of those that can be set, this is the only
+         * one which seems bad.
+         */
+        if (error_code & 0x10000000)
+                /* Guarded storage error. */
+                goto bad_area;
+#endif /* CONFIG_8xx */
+
+        /* a write */
+        if (is_write) {
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
+        /* an exec  - 4xx/Book-E allows for per-page execute permission */
+        } else if (TRAP(regs) == 0x400) {
+                pte_t *ptep;
+
+#if 0
+                /* It would be nice to actually enforce the VM execute
+                   permission on CPUs which can do so, but far too
+                   much stuff in userspace doesn't get the permissions
+                   right, so we let any page be executed for now. */
+                if (! (vma->vm_flags & VM_EXEC))
+                        goto bad_area;
+#endif
+
+                /* Since 4xx/Book-E supports per-page execute permission,
+                 * we lazily flush dcache to icache. */
+                ptep = NULL;
+                if (get_pteptr(mm, address, &ptep) && pte_present(*ptep)) {
+                        struct page *page = pte_page(*ptep);
+
+                        if (! test_bit(PG_arch_1, &page->flags)) {
+                                flush_dcache_icache_page(page);
+                                set_bit(PG_arch_1, &page->flags);
+                        }
+                        pte_update(ptep, 0, _PAGE_HWEXEC);
+                        _tlbie(address);
+                        pte_unmap(ptep);
+                        up_read(&mm->mmap_sem);
+                        return 0;
+                }
+                if (ptep != NULL)
+                        pte_unmap(ptep);
+#endif
+        /* a read */
+        } else {
+                /* protection fault */
+                if (error_code & 0x08000000)
+                        goto bad_area;
+                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.
+         */
+ survive:
+        switch (handle_mm_fault(mm, vma, address, is_write)) {
+        case VM_FAULT_MINOR:
+                current->min_flt++;
+                break;
+        case VM_FAULT_MAJOR:
+                current->maj_flt++;
+                break;
+        case VM_FAULT_SIGBUS:
+                goto do_sigbus;
+        case VM_FAULT_OOM:
+                goto out_of_memory;
+        default:
+                BUG();
+        }
+
+        up_read(&mm->mmap_sem);
+        /*
+         * keep track of tlb+htab misses that are good addrs but
+         * just need pte's created via handle_mm_fault()
+         * -- Cort
+         */
+        pte_misses++;
+        return 0;
+
+bad_area:
+        up_read(&mm->mmap_sem);
+        pte_errors++;
+
+        /* User mode accesses cause a SIGSEGV */
+        if (user_mode(regs)) {
+                info.si_signo = SIGSEGV;
+                info.si_errno = 0;
+                info.si_code = code;
+                info.si_addr = (void __user *) address;
+                force_sig_info(SIGSEGV, &info, current);
+                return 0;
+        }
+
+        return SIGSEGV;
+
+/*
+ * 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);
+        if (current->pid == 1) {
+                yield();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        printk("VM: killing process %s\n", current->comm);
+        if (user_mode(regs))
+                do_exit(SIGKILL);
+        return SIGKILL;
+
+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;
+        force_sig_info (SIGBUS, &info, current);
+        if (!user_mode(regs))
+                return SIGBUS;
+        return 0;
+}
+
+/*
+ * bad_page_fault is called when we have a bad access from the kernel.
+ * It is called from the DSI and ISI handlers in head.S and from some
+ * of the procedures in traps.c.
+ */
+void
+bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
+{
+        const struct exception_table_entry *entry;
+
+        /* Are we prepared to handle this fault?  */
+        if ((entry = search_exception_tables(regs->nip)) != NULL) {
+                regs->nip = entry->fixup;
+                return;
+        }
+
+        /* kernel has accessed a bad area */
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+        if (debugger_kernel_faults)
+                debugger(regs);
+#endif
+        die("kernel access of bad area", regs, sig);
+}
+
+#ifdef CONFIG_8xx
+
+/* The pgtable.h claims some functions generically exist, but I
+ * can't find them......
+ */
+pte_t *va_to_pte(unsigned long address)
+{
+        pgd_t *dir;
+        pmd_t *pmd;
+        pte_t *pte;
+
+        if (address < TASK_SIZE)
+                return NULL;
+
+        dir = pgd_offset(&init_mm, address);
+        if (dir) {
+                pmd = pmd_offset(dir, address & PAGE_MASK);
+                if (pmd && pmd_present(*pmd)) {
+                        pte = pte_offset_kernel(pmd, address & PAGE_MASK);
+                        if (pte && pte_present(*pte))
+                                return(pte);
+                }
+        }
+        return NULL;
+}
+
+unsigned long va_to_phys(unsigned long address)
+{
+        pte_t *pte;
+
+        pte = va_to_pte(address);
+        if (pte)
+                return(((unsigned long)(pte_val(*pte)) & PAGE_MASK) | (address & ~(PAGE_MASK)));
+        return (0);
+}
+
+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(pgd, 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(pgd, 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);
+}
+#endif /* CONFIG_8xx */