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-rw-r--r--arch/ppc/mm/fault.c440
1 files changed, 440 insertions, 0 deletions
diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c
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+++ 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 */
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