+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-/*
- * arch/cris/mm/fault.c
- *
- * Copyright (C) 2000-2010 Axis Communications AB
- */
-
-#include <linux/mm.h>
-#include <linux/interrupt.h>
-#include <linux/extable.h>
-#include <linux/wait.h>
-#include <linux/sched/signal.h>
-#include <linux/uaccess.h>
-#include <arch/system.h>
-
-extern int find_fixup_code(struct pt_regs *);
-extern void die_if_kernel(const char *, struct pt_regs *, long);
-extern void show_registers(struct pt_regs *regs);
-
-/* debug of low-level TLB reload */
-#undef DEBUG
-
-#ifdef DEBUG
-#define D(x) x
-#else
-#define D(x)
-#endif
-
-/* debug of higher-level faults */
-#define DPG(x)
-
-/* current active page directory */
-
-DEFINE_PER_CPU(pgd_t *, current_pgd);
-unsigned long cris_signal_return_page;
-
-/*
- * This routine handles page faults. It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
- *
- * Notice that the address we're given is aligned to the page the fault
- * occurred in, since we only get the PFN in R_MMU_CAUSE not the complete
- * address.
- *
- * error_code:
- * bit 0 == 0 means no page found, 1 means protection fault
- * bit 1 == 0 means read, 1 means write
- *
- * If this routine detects a bad access, it returns 1, otherwise it
- * returns 0.
- */
-
-asmlinkage void
-do_page_fault(unsigned long address, struct pt_regs *regs,
- int protection, int writeaccess)
-{
- struct task_struct *tsk;
- struct mm_struct *mm;
- struct vm_area_struct * vma;
- siginfo_t info;
- int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
-
- D(printk(KERN_DEBUG
- "Page fault for %lX on %X at %lX, prot %d write %d\n",
- address, smp_processor_id(), instruction_pointer(regs),
- protection, writeaccess));
-
- tsk = current;
-
- /*
- * 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.
- *
- * NOTE2: This is done so that, when updating the vmalloc
- * mappings we don't have to walk all processes pgdirs and
- * add the high mappings all at once. Instead we do it as they
- * are used. However vmalloc'ed page entries have the PAGE_GLOBAL
- * bit set so sometimes the TLB can use a lingering entry.
- *
- * This verifies that the fault happens in kernel space
- * and that the fault was not a protection error (error_code & 1).
- */
-
- if (address >= VMALLOC_START &&
- !protection &&
- !user_mode(regs))
- goto vmalloc_fault;
-
- /* When stack execution is not allowed we store the signal
- * trampolines in the reserved cris_signal_return_page.
- * Handle this in the exact same way as vmalloc (we know
- * that the mapping is there and is valid so no need to
- * call handle_mm_fault).
- */
- if (cris_signal_return_page &&
- address == cris_signal_return_page &&
- !protection && user_mode(regs))
- goto vmalloc_fault;
-
- /* we can and should enable interrupts at this point */
- local_irq_enable();
-
- mm = tsk->mm;
- info.si_code = SEGV_MAPERR;
-
- /*
- * If we're in an interrupt, have pagefaults disabled or have no
- * user context, we must not take the fault.
- */
-
- if (faulthandler_disabled() || !mm)
- goto no_context;
-
- if (user_mode(regs))
- flags |= FAULT_FLAG_USER;
-retry:
- 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 (user_mode(regs)) {
- /*
- * accessing the stack below usp is always a bug.
- * we get page-aligned addresses so we can only check
- * if we're within a page from usp, but that might be
- * enough to catch brutal errors at least.
- */
- if (address + PAGE_SIZE < rdusp())
- 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;
-
- /* first do some preliminary protection checks */
-
- if (writeaccess == 2){
- if (!(vma->vm_flags & VM_EXEC))
- goto bad_area;
- } else if (writeaccess == 1) {
- if (!(vma->vm_flags & VM_WRITE))
- goto bad_area;
- flags |= FAULT_FLAG_WRITE;
- } else {
- 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(vma, address, flags);
-
- if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
- return;
-
- if (unlikely(fault & VM_FAULT_ERROR)) {
- if (fault & VM_FAULT_OOM)
- goto out_of_memory;
- else if (fault & VM_FAULT_SIGSEGV)
- goto bad_area;
- else if (fault & VM_FAULT_SIGBUS)
- goto do_sigbus;
- BUG();
- }
-
- if (flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR)
- tsk->maj_flt++;
- else
- tsk->min_flt++;
- if (fault & VM_FAULT_RETRY) {
- flags &= ~FAULT_FLAG_ALLOW_RETRY;
- flags |= FAULT_FLAG_TRIED;
-
- /*
- * No need to up_read(&mm->mmap_sem) as we would
- * have already released it in __lock_page_or_retry
- * in mm/filemap.c.
- */
-
- goto retry;
- }
- }
-
- 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:
- DPG(show_registers(regs));
-
- /* User mode accesses just cause a SIGSEGV */
-
- if (user_mode(regs)) {
-#ifdef CONFIG_NO_SEGFAULT_TERMINATION
- DECLARE_WAIT_QUEUE_HEAD(wq);
-#endif
- printk(KERN_NOTICE "%s (pid %d) segfaults for page "
- "address %08lx at pc %08lx\n",
- tsk->comm, tsk->pid,
- address, instruction_pointer(regs));
-
- /* With DPG on, we've already dumped registers above. */
- DPG(if (0))
- show_registers(regs);
-
-#ifdef CONFIG_NO_SEGFAULT_TERMINATION
- wait_event_interruptible(wq, 0 == 1);
-#else
- info.si_signo = SIGSEGV;
- info.si_errno = 0;
- /* info.si_code has been set above */
- info.si_addr = (void *)address;
- force_sig_info(SIGSEGV, &info, tsk);
-#endif
- return;
- }
-
- no_context:
-
- /* Are we prepared to handle this kernel fault?
- *
- * (The kernel has valid exception-points in the source
- * when it accesses user-memory. When it fails in one
- * of those points, we find it in a table and do a jump
- * to some fixup code that loads an appropriate error
- * code)
- */
-
- if (find_fixup_code(regs))
- return;
-
- /*
- * Oops. The kernel tried to access some bad page. We'll have to
- * terminate things with extreme prejudice.
- */
-
- if (!oops_in_progress) {
- oops_in_progress = 1;
- if ((unsigned long) (address) < PAGE_SIZE)
- printk(KERN_ALERT "Unable to handle kernel NULL "
- "pointer dereference");
- else
- printk(KERN_ALERT "Unable to handle kernel access"
- " at virtual address %08lx\n", address);
-
- die_if_kernel("Oops", regs, (writeaccess << 1) | protection);
- oops_in_progress = 0;
- }
-
- 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);
- if (!user_mode(regs))
- goto no_context;
- pagefault_out_of_memory();
- return;
-
- do_sigbus:
- up_read(&mm->mmap_sem);
-
- /*
- * Send a sigbus, regardless of whether we were in kernel
- * or user mode.
- */
- info.si_signo = SIGBUS;
- info.si_errno = 0;
- info.si_code = BUS_ADRERR;
- info.si_addr = (void *)address;
- force_sig_info(SIGBUS, &info, tsk);
-
- /* Kernel mode? Handle exceptions or die */
- if (!user_mode(regs))
- goto no_context;
- return;
-
-vmalloc_fault:
- {
- /*
- * Synchronize this task's top level page-table
- * with the 'reference' page table.
- *
- * Use current_pgd instead of tsk->active_mm->pgd
- * since the latter might be unavailable if this
- * code is executed in a misfortunately run irq
- * (like inside schedule() between switch_mm and
- * switch_to...).
- */
-
- int offset = pgd_index(address);
- pgd_t *pgd, *pgd_k;
- pud_t *pud, *pud_k;
- pmd_t *pmd, *pmd_k;
- pte_t *pte_k;
-
- pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset;
- pgd_k = init_mm.pgd + offset;
-
- /* Since we're two-level, we don't need to do both
- * set_pgd and set_pmd (they do the same thing). If
- * we go three-level at some point, do the right thing
- * with pgd_present and set_pgd here.
- *
- * Also, since the vmalloc area is global, we don't
- * need to copy individual PTE's, it is enough to
- * copy the pgd pointer into the pte page of the
- * root task. If that is there, we'll find our pte if
- * it exists.
- */
-
- pud = pud_offset(pgd, address);
- pud_k = pud_offset(pgd_k, address);
- if (!pud_present(*pud_k))
- goto no_context;
-
- pmd = pmd_offset(pud, address);
- pmd_k = pmd_offset(pud_k, address);
-
- if (!pmd_present(*pmd_k))
- goto bad_area_nosemaphore;
-
- set_pmd(pmd, *pmd_k);
-
- /* Make sure the actual PTE exists as well to
- * catch kernel vmalloc-area accesses to non-mapped
- * addresses. If we don't do this, this will just
- * silently loop forever.
- */
-
- pte_k = pte_offset_kernel(pmd_k, address);
- if (!pte_present(*pte_k))
- goto no_context;
-
- return;
- }
-}
-
-/* Find fixup code. */
-int
-find_fixup_code(struct pt_regs *regs)
-{
- const struct exception_table_entry *fixup;
- /* in case of delay slot fault (v32) */
- unsigned long ip = (instruction_pointer(regs) & ~0x1);
-
- fixup = search_exception_tables(ip);
- if (fixup != 0) {
- /* Adjust the instruction pointer in the stackframe. */
- instruction_pointer(regs) = fixup->fixup;
- arch_fixup(regs);
- return 1;
- }
-
- return 0;
-}
git.samba.org / sfrench / cifs-2.6.git / blobdiff