253 lines
6.1 KiB
C
253 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/arch/alpha/mm/fault.c
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*
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* Copyright (C) 1995 Linus Torvalds
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*/
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#include <linux/sched/signal.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <asm/io.h>
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#define __EXTERN_INLINE inline
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#undef __EXTERN_INLINE
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/extable.h>
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#include <linux/uaccess.h>
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extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
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/*
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* Force a new ASN for a task.
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*/
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#ifndef CONFIG_SMP
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unsigned long last_asn = ASN_FIRST_VERSION;
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#endif
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void
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__load_new_mm_context(struct mm_struct *next_mm)
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{
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unsigned long mmc;
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struct pcb_struct *pcb;
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mmc = __get_new_mm_context(next_mm, smp_processor_id());
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next_mm->context[smp_processor_id()] = mmc;
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pcb = ¤t_thread_info()->pcb;
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pcb->asn = mmc & HARDWARE_ASN_MASK;
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pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
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__reload_thread(pcb);
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to handle_mm_fault().
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*
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* mmcsr:
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* 0 = translation not valid
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* 1 = access violation
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* 2 = fault-on-read
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* 3 = fault-on-execute
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* 4 = fault-on-write
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*
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* cause:
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* -1 = instruction fetch
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* 0 = load
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* 1 = store
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*
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* Registers $9 through $15 are saved in a block just prior to `regs' and
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* are saved and restored around the call to allow exception code to
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* modify them.
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*/
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/* Macro for exception fixup code to access integer registers. */
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#define dpf_reg(r) \
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(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
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(r) <= 18 ? (r)+10 : (r)-10])
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asmlinkage void
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do_page_fault(unsigned long address, unsigned long mmcsr,
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long cause, struct pt_regs *regs)
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{
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struct vm_area_struct * vma;
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struct mm_struct *mm = current->mm;
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const struct exception_table_entry *fixup;
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int si_code = SEGV_MAPERR;
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vm_fault_t fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
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(or is suppressed by the PALcode). Support that for older CPUs
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by ignoring such an instruction. */
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if (cause == 0) {
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unsigned int insn;
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__get_user(insn, (unsigned int __user *)regs->pc);
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if ((insn >> 21 & 0x1f) == 0x1f &&
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/* ldq ldl ldt lds ldg ldf ldwu ldbu */
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(1ul << (insn >> 26) & 0x30f00001400ul)) {
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regs->pc += 4;
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return;
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}
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}
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/* If we're in an interrupt context, or have no user context,
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we must not take the fault. */
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if (!mm || faulthandler_disabled())
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goto no_context;
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#ifdef CONFIG_ALPHA_LARGE_VMALLOC
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if (address >= TASK_SIZE)
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goto vmalloc_fault;
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#endif
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/* Ok, we have a good vm_area for this memory access, so
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we can handle it. */
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good_area:
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si_code = SEGV_ACCERR;
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if (cause < 0) {
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if (!(vma->vm_flags & VM_EXEC))
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goto bad_area;
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} else if (!cause) {
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/* Allow reads even for write-only mappings */
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if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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flags |= FAULT_FLAG_WRITE;
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}
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/* If for any reason at all we couldn't handle the fault,
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make sure we exit gracefully rather than endlessly redo
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the fault. */
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fault = handle_mm_fault(vma, address, flags);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return;
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGSEGV)
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goto bad_area;
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else if (fault & VM_FAULT_SIGBUS)
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goto do_sigbus;
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BUG();
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}
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR)
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current->maj_flt++;
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else
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* in mm/filemap.c.
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*/
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goto retry;
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}
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}
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up_read(&mm->mmap_sem);
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return;
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/* Something tried to access memory that isn't in our memory map.
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Fix it, but check if it's kernel or user first. */
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bad_area:
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up_read(&mm->mmap_sem);
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if (user_mode(regs))
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goto do_sigsegv;
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no_context:
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/* Are we prepared to handle this fault as an exception? */
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if ((fixup = search_exception_tables(regs->pc)) != 0) {
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unsigned long newpc;
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newpc = fixup_exception(dpf_reg, fixup, regs->pc);
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regs->pc = newpc;
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return;
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}
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/* Oops. The kernel tried to access some bad page. We'll have to
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terminate things with extreme prejudice. */
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printk(KERN_ALERT "Unable to handle kernel paging request at "
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"virtual address %016lx\n", address);
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die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
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do_exit(SIGKILL);
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/* We ran out of memory, or some other thing happened to us that
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made us unable to handle the page fault gracefully. */
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (!user_mode(regs))
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goto no_context;
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pagefault_out_of_memory();
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return;
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do_sigbus:
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up_read(&mm->mmap_sem);
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/* Send a sigbus, regardless of whether we were in kernel
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or user mode. */
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force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0, current);
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if (!user_mode(regs))
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goto no_context;
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return;
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do_sigsegv:
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force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0, current);
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return;
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#ifdef CONFIG_ALPHA_LARGE_VMALLOC
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vmalloc_fault:
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if (user_mode(regs))
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goto do_sigsegv;
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else {
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/* Synchronize this task's top level page-table
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with the "reference" page table from init. */
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long index = pgd_index(address);
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pgd_t *pgd, *pgd_k;
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pgd = current->active_mm->pgd + index;
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pgd_k = swapper_pg_dir + index;
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if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
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pgd_val(*pgd) = pgd_val(*pgd_k);
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return;
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}
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goto no_context;
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}
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#endif
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}
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