--- /dev/null
+/*
+ * linux/arch/alpha/mm/fault.c
+ *
+ * Copyright (C) 1995 Linus Torvalds
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <asm/io.h>
+
+#define __EXTERN_INLINE inline
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#undef __EXTERN_INLINE
+
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+
+extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
+
+
+/*
+ * Force a new ASN for a task.
+ */
+
+#ifndef CONFIG_SMP
+unsigned long last_asn = ASN_FIRST_VERSION;
+#endif
+
+void
+__load_new_mm_context(struct mm_struct *next_mm)
+{
+ unsigned long mmc;
+ struct pcb_struct *pcb;
+
+ mmc = __get_new_mm_context(next_mm, smp_processor_id());
+ next_mm->context[smp_processor_id()] = mmc;
+
+ pcb = ¤t_thread_info()->pcb;
+ pcb->asn = mmc & HARDWARE_ASN_MASK;
+ pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
+
+ __reload_thread(pcb);
+}
+
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to handle_mm_fault().
+ *
+ * mmcsr:
+ * 0 = translation not valid
+ * 1 = access violation
+ * 2 = fault-on-read
+ * 3 = fault-on-execute
+ * 4 = fault-on-write
+ *
+ * cause:
+ * -1 = instruction fetch
+ * 0 = load
+ * 1 = store
+ *
+ * Registers $9 through $15 are saved in a block just prior to `regs' and
+ * are saved and restored around the call to allow exception code to
+ * modify them.
+ */
+
+/* Macro for exception fixup code to access integer registers. */
+#define dpf_reg(r) \
+ (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
+ (r) <= 18 ? (r)+8 : (r)-10])
+
+asmlinkage void
+do_page_fault(unsigned long address, unsigned long mmcsr,
+ long cause, struct pt_regs *regs)
+{
+ struct vm_area_struct * vma;
+ struct mm_struct *mm = current->mm;
+ const struct exception_table_entry *fixup;
+ int fault, si_code = SEGV_MAPERR;
+ siginfo_t info;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+
+ /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
+ (or is suppressed by the PALcode). Support that for older CPUs
+ by ignoring such an instruction. */
+ if (cause == 0) {
+ unsigned int insn;
+ __get_user(insn, (unsigned int __user *)regs->pc);
+ if ((insn >> 21 & 0x1f) == 0x1f &&
+ /* ldq ldl ldt lds ldg ldf ldwu ldbu */
+ (1ul << (insn >> 26) & 0x30f00001400ul)) {
+ regs->pc += 4;
+ return;
+ }
+ }
+
+ /* If we're in an interrupt context, or have no user context,
+ we must not take the fault. */
+ if (!mm || faulthandler_disabled())
+ goto no_context;
+
+#ifdef CONFIG_ALPHA_LARGE_VMALLOC
+ if (address >= TASK_SIZE)
+ goto vmalloc_fault;
+#endif
+ 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 (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:
+ si_code = SEGV_ACCERR;
+ if (cause < 0) {
+ if (!(vma->vm_flags & VM_EXEC))
+ goto bad_area;
+ } else if (!cause) {
+ /* Allow reads even for write-only mappings */
+ if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
+ goto bad_area;
+ } else {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
+ }
+
+ /* 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(mm, 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)
+ current->maj_flt++;
+ else
+ current->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+ /* 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);
+
+ if (user_mode(regs))
+ goto do_sigsegv;
+
+ no_context:
+ /* Are we prepared to handle this fault as an exception? */
+ if ((fixup = search_exception_tables(regs->pc)) != 0) {
+ unsigned long newpc;
+ newpc = fixup_exception(dpf_reg, fixup, regs->pc);
+ regs->pc = newpc;
+ return;
+ }
+
+ /* Oops. The kernel tried to access some bad page. We'll have to
+ terminate things with extreme prejudice. */
+ printk(KERN_ALERT "Unable to handle kernel paging request at "
+ "virtual address %016lx\n", address);
+ die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
+ 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 __user *) address;
+ force_sig_info(SIGBUS, &info, current);
+ if (!user_mode(regs))
+ goto no_context;
+ return;
+
+ do_sigsegv:
+ info.si_signo = SIGSEGV;
+ info.si_errno = 0;
+ info.si_code = si_code;
+ info.si_addr = (void __user *) address;
+ force_sig_info(SIGSEGV, &info, current);
+ return;
+
+#ifdef CONFIG_ALPHA_LARGE_VMALLOC
+ vmalloc_fault:
+ if (user_mode(regs))
+ goto do_sigsegv;
+ else {
+ /* Synchronize this task's top level page-table
+ with the "reference" page table from init. */
+ long index = pgd_index(address);
+ pgd_t *pgd, *pgd_k;
+
+ pgd = current->active_mm->pgd + index;
+ pgd_k = swapper_pg_dir + index;
+ if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
+ pgd_val(*pgd) = pgd_val(*pgd_k);
+ return;
+ }
+ goto no_context;
+ }
+#endif
+}
Code Review / kvmfornfv.git / blobdiff