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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mm/fault.c
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/arm/mm/fault.c')
-rw-r--r--arch/arm/mm/fault.c462
1 files changed, 462 insertions, 0 deletions
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
new file mode 100644
index 000000000000..29be1c018949
--- /dev/null
+++ b/arch/arm/mm/fault.c
@@ -0,0 +1,462 @@
+/*
+ * linux/arch/arm/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ * Modifications for ARM processor (c) 1995-2004 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/module.h>
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/uaccess.h>
+
+#include "fault.h"
+
+/*
+ * 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;
+
+ if (pgd_none(*pgd))
+ break;
+
+ if (pgd_bad(*pgd)) {
+ printk("(bad)");
+ break;
+ }
+
+ pmd = pmd_offset(pgd, addr);
+#if PTRS_PER_PMD != 1
+ printk(", *pmd=%08lx", pmd_val(*pmd));
+#endif
+
+ if (pmd_none(*pmd))
+ break;
+
+ if (pmd_bad(*pmd)) {
+ printk("(bad)");
+ break;
+ }
+
+#ifndef CONFIG_HIGHMEM
+ /* We must not map this if we have highmem enabled */
+ pte = pte_offset_map(pmd, addr);
+ printk(", *pte=%08lx", pte_val(*pte));
+ printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
+ pte_unmap(pte);
+#endif
+ } 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
+ if (user_debug & UDBG_SEGV) {
+ printk(KERN_DEBUG "%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
+ tsk->comm, addr, fsr);
+ show_pte(tsk->mm, addr);
+ show_regs(regs);
+ }
+#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 __user *)addr;
+ force_sig_info(SIGSEGV, &si, tsk);
+}
+
+void
+do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr,
+ unsigned int fsr, struct pt_regs *regs)
+{
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ */
+ if (user_mode(regs))
+ __do_user_fault(tsk, addr, fsr, SEGV_MAPERR, regs);
+ else
+ __do_kernel_fault(mm, addr, fsr, regs);
+}
+
+#define VM_FAULT_BADMAP (-20)
+#define VM_FAULT_BADACCESS (-21)
+
+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 = VM_FAULT_BADMAP;
+ 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 (fsr & (1 << 11)) /* write? */
+ mask = VM_WRITE;
+ else
+ mask = VM_READ|VM_EXEC;
+
+ fault = VM_FAULT_BADACCESS;
+ 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, fsr & (1 << 11));
+
+ /*
+ * Handle the "normal" cases first - successful and sigbus
+ */
+ switch (fault) {
+ case VM_FAULT_MAJOR:
+ tsk->maj_flt++;
+ return fault;
+ case VM_FAULT_MINOR:
+ tsk->min_flt++;
+ case VM_FAULT_SIGBUS:
+ return fault;
+ }
+
+ 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;
+}
+
+static 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.
+ */
+ if (!user_mode(regs))
+ goto no_context;
+
+ if (fault == VM_FAULT_OOM) {
+ /*
+ * 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 == VM_FAULT_BADACCESS ?
+ 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;
+ tsk->thread.error_code = fsr;
+ tsk->thread.trap_no = 14;
+ force_sig(SIGBUS, tsk);
+#ifdef CONFIG_DEBUG_USER
+ if (user_debug & UDBG_BUS) {
+ 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;
+}
+
+/*
+ * First Level Translation Fault Handler
+ *
+ * We enter here because the first level page table doesn't contain
+ * a valid entry for the address.
+ *
+ * If the address is in kernel space (>= TASK_SIZE), then we are
+ * probably faulting in the vmalloc() area.
+ *
+ * If the init_task's first level page tables contains the relevant
+ * entry, we copy the it to this task. If not, we send the process
+ * a signal, fixup the exception, or oops the kernel.
+ *
+ * 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.
+ */
+static int
+do_translation_fault(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ unsigned int index;
+ pgd_t *pgd, *pgd_k;
+ pmd_t *pmd, *pmd_k;
+
+ if (addr < TASK_SIZE)
+ return do_page_fault(addr, fsr, regs);
+
+ index = pgd_index(addr);
+
+ /*
+ * FIXME: CP15 C1 is write only on ARMv3 architectures.
+ */
+ pgd = cpu_get_pgd() + index;
+ pgd_k = init_mm.pgd + index;
+
+ if (pgd_none(*pgd_k))
+ goto bad_area;
+
+ if (!pgd_present(*pgd))
+ set_pgd(pgd, *pgd_k);
+
+ pmd_k = pmd_offset(pgd_k, addr);
+ pmd = pmd_offset(pgd, addr);
+
+ if (pmd_none(*pmd_k))
+ goto bad_area;
+
+ copy_pmd(pmd, pmd_k);
+ return 0;
+
+bad_area:
+ tsk = current;
+
+ do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
+ return 0;
+}
+
+/*
+ * Some section permission faults need to be handled gracefully.
+ * They can happen due to a __{get,put}_user during an oops.
+ */
+static int
+do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ struct task_struct *tsk = current;
+ do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
+ return 0;
+}
+
+/*
+ * This abort handler always returns "fault".
+ */
+static int
+do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ return 1;
+}
+
+static struct fsr_info {
+ int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+ int sig;
+ const char *name;
+} fsr_info[] = {
+ /*
+ * The following are the standard ARMv3 and ARMv4 aborts. ARMv5
+ * defines these to be "precise" aborts.
+ */
+ { do_bad, SIGSEGV, "vector exception" },
+ { do_bad, SIGILL, "alignment exception" },
+ { do_bad, SIGKILL, "terminal exception" },
+ { do_bad, SIGILL, "alignment exception" },
+ { do_bad, SIGBUS, "external abort on linefetch" },
+ { do_translation_fault, SIGSEGV, "section translation fault" },
+ { do_bad, SIGBUS, "external abort on linefetch" },
+ { do_page_fault, SIGSEGV, "page translation fault" },
+ { do_bad, SIGBUS, "external abort on non-linefetch" },
+ { do_bad, SIGSEGV, "section domain fault" },
+ { do_bad, SIGBUS, "external abort on non-linefetch" },
+ { do_bad, SIGSEGV, "page domain fault" },
+ { do_bad, SIGBUS, "external abort on translation" },
+ { do_sect_fault, SIGSEGV, "section permission fault" },
+ { do_bad, SIGBUS, "external abort on translation" },
+ { do_page_fault, SIGSEGV, "page permission fault" },
+ /*
+ * The following are "imprecise" aborts, which are signalled by bit
+ * 10 of the FSR, and may not be recoverable. These are only
+ * supported if the CPU abort handler supports bit 10.
+ */
+ { do_bad, SIGBUS, "unknown 16" },
+ { do_bad, SIGBUS, "unknown 17" },
+ { do_bad, SIGBUS, "unknown 18" },
+ { do_bad, SIGBUS, "unknown 19" },
+ { do_bad, SIGBUS, "lock abort" }, /* xscale */
+ { do_bad, SIGBUS, "unknown 21" },
+ { do_bad, SIGBUS, "imprecise external abort" }, /* xscale */
+ { do_bad, SIGBUS, "unknown 23" },
+ { do_bad, SIGBUS, "dcache parity error" }, /* xscale */
+ { do_bad, SIGBUS, "unknown 25" },
+ { do_bad, SIGBUS, "unknown 26" },
+ { do_bad, SIGBUS, "unknown 27" },
+ { do_bad, SIGBUS, "unknown 28" },
+ { do_bad, SIGBUS, "unknown 29" },
+ { do_bad, SIGBUS, "unknown 30" },
+ { do_bad, SIGBUS, "unknown 31" }
+};
+
+void __init
+hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+ int sig, const char *name)
+{
+ if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
+ fsr_info[nr].fn = fn;
+ fsr_info[nr].sig = sig;
+ fsr_info[nr].name = name;
+ }
+}
+
+/*
+ * Dispatch a data abort to the relevant handler.
+ */
+asmlinkage void
+do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
+
+ if (!inf->fn(addr, fsr, regs))
+ return;
+
+ printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
+ inf->name, fsr, addr);
+ force_sig(inf->sig, current);
+ show_pte(current->mm, addr);
+ die_if_kernel("Oops", regs, 0);
+}
+
+asmlinkage void
+do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+{
+ do_translation_fault(addr, 0, regs);
+}
+