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-rw-r--r--arch/arm26/mm/fault.c318
1 files changed, 318 insertions, 0 deletions
diff --git a/arch/arm26/mm/fault.c b/arch/arm26/mm/fault.c
new file mode 100644
index 000000000000..dacca8bb7744
--- /dev/null
+++ b/arch/arm26/mm/fault.c
@@ -0,0 +1,318 @@
+/*
+ * linux/arch/arm26/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ * Modifications for ARM processor (c) 1995-2001 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#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/proc_fs.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h> //FIXME this header may be bogusly included
+
+#include "fault.h"
+
+#define FAULT_CODE_LDRSTRPOST 0x80
+#define FAULT_CODE_LDRSTRPRE 0x40
+#define FAULT_CODE_LDRSTRREG 0x20
+#define FAULT_CODE_LDMSTM 0x10
+#define FAULT_CODE_LDCSTC 0x08
+#define FAULT_CODE_PREFETCH 0x04
+#define FAULT_CODE_WRITE 0x02
+#define FAULT_CODE_FORCECOW 0x01
+
+#define DO_COW(m) ((m) & (FAULT_CODE_WRITE|FAULT_CODE_FORCECOW))
+#define READ_FAULT(m) (!((m) & FAULT_CODE_WRITE))
+#define DEBUG
+/*
+ * This is useful to dump out the page tables associated with
+ * 'addr' in mm 'mm'.
+ */
+void show_pte(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgd;
+
+ if (!mm)
+ mm = &init_mm;
+
+ printk(KERN_ALERT "pgd = %p\n", mm->pgd);
+ pgd = pgd_offset(mm, addr);
+ printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
+
+ do {
+ pmd_t *pmd;
+ pte_t *pte;
+
+ pmd = pmd_offset(pgd, addr);
+
+ if (pmd_none(*pmd))
+ break;
+
+ if (pmd_bad(*pmd)) {
+ printk("(bad)");
+ break;
+ }
+
+ /* We must not map this if we have highmem enabled */
+ /* FIXME */
+ pte = pte_offset_map(pmd, addr);
+ printk(", *pte=%08lx", pte_val(*pte));
+ pte_unmap(pte);
+ } while(0);
+
+ printk("\n");
+}
+
+/*
+ * Oops. The kernel tried to access some page that wasn't present.
+ */
+static void
+__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ /*
+ * Are we prepared to handle this kernel fault?
+ */
+ if (fixup_exception(regs))
+ return;
+
+ /*
+ * No handler, we'll have to terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+ printk(KERN_ALERT
+ "Unable to handle kernel %s at virtual address %08lx\n",
+ (addr < PAGE_SIZE) ? "NULL pointer dereference" :
+ "paging request", addr);
+
+ show_pte(mm, addr);
+ die("Oops", regs, fsr);
+ bust_spinlocks(0);
+ do_exit(SIGKILL);
+}
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * User mode accesses just cause a SIGSEGV
+ */
+static void
+__do_user_fault(struct task_struct *tsk, unsigned long addr,
+ unsigned int fsr, int code, struct pt_regs *regs)
+{
+ struct siginfo si;
+
+#ifdef CONFIG_DEBUG_USER
+ printk("%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
+ tsk->comm, addr, fsr);
+ show_pte(tsk->mm, addr);
+ show_regs(regs);
+ //dump_backtrace(regs, tsk); // FIXME ARM32 dropped this - why?
+ while(1); //FIXME - hack to stop debug going nutso
+#endif
+
+ tsk->thread.address = addr;
+ tsk->thread.error_code = fsr;
+ tsk->thread.trap_no = 14;
+ si.si_signo = SIGSEGV;
+ si.si_errno = 0;
+ si.si_code = code;
+ si.si_addr = (void *)addr;
+ force_sig_info(SIGSEGV, &si, tsk);
+}
+
+static int
+__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+ struct task_struct *tsk)
+{
+ struct vm_area_struct *vma;
+ int fault, mask;
+
+ vma = find_vma(mm, addr);
+ fault = -2; /* bad map area */
+ if (!vma)
+ goto out;
+ if (vma->vm_start > addr)
+ goto check_stack;
+
+ /*
+ * Ok, we have a good vm_area for this
+ * memory access, so we can handle it.
+ */
+good_area:
+ if (READ_FAULT(fsr)) /* read? */
+ mask = VM_READ|VM_EXEC;
+ else
+ mask = VM_WRITE;
+
+ fault = -1; /* bad access type */
+ if (!(vma->vm_flags & mask))
+ goto out;
+
+ /*
+ * If for any reason at all we couldn't handle
+ * the fault, make sure we exit gracefully rather
+ * than endlessly redo the fault.
+ */
+survive:
+ fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
+
+ /*
+ * Handle the "normal" cases first - successful and sigbus
+ */
+ switch (fault) {
+ case 2:
+ tsk->maj_flt++;
+ return fault;
+ case 1:
+ tsk->min_flt++;
+ case 0:
+ return fault;
+ }
+
+ fault = -3; /* out of memory */
+ if (tsk->pid != 1)
+ goto out;
+
+ /*
+ * If we are out of memory for pid1,
+ * sleep for a while and retry
+ */
+ yield();
+ goto survive;
+
+check_stack:
+ if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
+ goto good_area;
+out:
+ return fault;
+}
+
+int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ int fault;
+
+ tsk = current;
+ mm = tsk->mm;
+
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (in_interrupt() || !mm)
+ goto no_context;
+
+ down_read(&mm->mmap_sem);
+ fault = __do_page_fault(mm, addr, fsr, tsk);
+ up_read(&mm->mmap_sem);
+
+ /*
+ * Handle the "normal" case first
+ */
+ if (fault > 0)
+ return 0;
+
+ /*
+ * We had some memory, but were unable to
+ * successfully fix up this page fault.
+ */
+ if (fault == 0){
+ goto do_sigbus;
+ }
+
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ * FIXME - is this test right?
+ */
+ if (!user_mode(regs)){
+ goto no_context;
+ }
+
+ if (fault == -3) {
+ /*
+ * We ran out of memory, or some other thing happened to
+ * us that made us unable to handle the page fault gracefully.
+ */
+ printk("VM: killing process %s\n", tsk->comm);
+ do_exit(SIGKILL);
+ }
+ else{
+ __do_user_fault(tsk, addr, fsr, fault == -1 ? SEGV_ACCERR : SEGV_MAPERR, regs);
+ }
+
+ return 0;
+
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+do_sigbus:
+ /*
+ * Send a sigbus, regardless of whether we were in kernel
+ * or user mode.
+ */
+ tsk->thread.address = addr; //FIXME - need other bits setting?
+ tsk->thread.error_code = fsr;
+ tsk->thread.trap_no = 14;
+ force_sig(SIGBUS, tsk);
+#ifdef CONFIG_DEBUG_USER
+ printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n",
+ current->comm, addr, instruction_pointer(regs));
+#endif
+
+ /* Kernel mode? Handle exceptions or die */
+ if (user_mode(regs))
+ return 0;
+
+no_context:
+ __do_kernel_fault(mm, addr, fsr, regs);
+ return 0;
+}
+
+/*
+ * Handle a data abort. Note that we have to handle a range of addresses
+ * on ARM2/3 for ldm. If both pages are zero-mapped, then we have to force
+ * a copy-on-write. However, on the second page, we always force COW.
+ */
+asmlinkage void
+do_DataAbort(unsigned long min_addr, unsigned long max_addr, int mode, struct pt_regs *regs)
+{
+ do_page_fault(min_addr, mode, regs);
+
+ if ((min_addr ^ max_addr) >> PAGE_SHIFT){
+ do_page_fault(max_addr, mode | FAULT_CODE_FORCECOW, regs);
+ }
+}
+
+asmlinkage int
+do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+{
+#if 0
+ if (the memc mapping for this page exists) {
+ printk ("Page in, but got abort (undefined instruction?)\n");
+ return 0;
+ }
+#endif
+ do_page_fault(addr, FAULT_CODE_PREFETCH, regs);
+ return 1;
+}
+
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