patch-2.4.2 linux/arch/cris/mm/fault.c
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- Lines: 391
- Date:
Thu Feb 8 16:32:44 2001
- Orig file:
v2.4.1/linux/arch/cris/mm/fault.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.4.1/linux/arch/cris/mm/fault.c linux/arch/cris/mm/fault.c
@@ -0,0 +1,390 @@
+/*
+ * linux/arch/cris/mm/fault.c
+ *
+ * Copyright (C) 2000 Axis Communications AB
+ *
+ * Authors: Bjorn Wesen
+ *
+ * $Log: fault.c,v $
+ * Revision 1.8 2000/11/22 14:45:31 bjornw
+ * * 2.4.0-test10 removed the set_pgdir instantaneous kernel global mapping
+ * into all processes. Instead we fill in the missing PTE entries on demand.
+ *
+ * Revision 1.7 2000/11/21 16:39:09 bjornw
+ * fixup switches frametype
+ *
+ * Revision 1.6 2000/11/17 16:54:08 bjornw
+ * More detailed siginfo reporting
+ *
+ *
+ */
+
+#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 <asm/system.h>
+#include <asm/segment.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/svinto.h>
+
+extern void die_if_kernel(const char *,struct pt_regs *,long);
+
+asmlinkage void do_invalid_op (struct pt_regs *, unsigned long);
+asmlinkage void do_page_fault(unsigned long address, struct pt_regs *regs,
+ int error_code);
+
+/* debug of low-level TLB reload */
+#define D(x)
+/* debug of higher-level faults */
+#define DPG(x)
+
+/* fast TLB-fill fault handler */
+
+void
+handle_mmu_bus_fault(struct pt_regs *regs)
+{
+ int cause, select;
+ int index;
+ int page_id;
+ int miss, we, acc, inv;
+ struct mm_struct *mm = current->active_mm;
+ pmd_t *pmd;
+ pte_t pte;
+ int errcode = 0;
+ unsigned long address;
+
+ cause = *R_MMU_CAUSE;
+ select = *R_TLB_SELECT;
+
+ address = cause & PAGE_MASK; /* get faulting address */
+
+ page_id = IO_EXTRACT(R_MMU_CAUSE, page_id, cause);
+ miss = IO_EXTRACT(R_MMU_CAUSE, miss_excp, cause);
+ we = IO_EXTRACT(R_MMU_CAUSE, we_excp, cause);
+ acc = IO_EXTRACT(R_MMU_CAUSE, acc_excp, cause);
+ inv = IO_EXTRACT(R_MMU_CAUSE, inv_excp, cause);
+ index = IO_EXTRACT(R_TLB_SELECT, index, select);
+
+ D(printk("bus_fault from IRP 0x%x: addr 0x%x, miss %d, inv %d, we %d, acc %d, "
+ "idx %d pid %d\n",
+ regs->irp, address, miss, inv, we, acc, index, page_id));
+
+ /* for a miss, we need to reload the TLB entry */
+
+ if(miss) {
+
+ /* see if the pte exists at all */
+
+ pmd = (pmd_t *)pgd_offset(mm, address);
+ if(pmd_none(*pmd))
+ goto dofault;
+ if(pmd_bad(*pmd)) {
+ printk("bad pgdir entry 0x%x at 0x%x\n", *pmd, pmd);
+ pmd_clear(pmd);
+ return;
+ }
+ pte = *pte_offset(pmd, address);
+ if(!pte_present(pte))
+ goto dofault;
+
+ D(printk(" found pte %x pg %x ", pte_val(pte), pte_page(pte)));
+ D(
+ {
+ if(pte_val(pte) & _PAGE_SILENT_WRITE)
+ printk("Silent-W ");
+ if(pte_val(pte) & _PAGE_KERNEL)
+ printk("Kernel ");
+ if(pte_val(pte) & _PAGE_SILENT_READ)
+ printk("Silent-R ");
+ if(pte_val(pte) & _PAGE_GLOBAL)
+ printk("Global ");
+ if(pte_val(pte) & _PAGE_PRESENT)
+ printk("Present ");
+ if(pte_val(pte) & _PAGE_ACCESSED)
+ printk("Accessed ");
+ if(pte_val(pte) & _PAGE_MODIFIED)
+ printk("Modified ");
+ if(pte_val(pte) & _PAGE_READ)
+ printk("Readable ");
+ if(pte_val(pte) & _PAGE_WRITE)
+ printk("Writeable ");
+ printk("\n");
+ });
+
+ /* load up the chosen TLB entry
+ * this assumes the pte format is the same as the TLB_LO layout.
+ *
+ * the write to R_TLB_LO also writes the vpn and page_id fields from
+ * R_MMU_CAUSE, which we in this case obviously want to keep
+ */
+
+ *R_TLB_LO = pte_val(pte);
+
+ return;
+ }
+
+ errcode = 0x01 | (we << 1);
+
+ dofault:
+ /* leave it to the MM system fault handler below */
+ D(printk("do_page_fault %p errcode %d\n", address, errcode));
+ do_page_fault(address, regs, errcode);
+}
+
+/*
+ * 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
+ * occured 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 error_code)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ struct vm_area_struct * vma;
+ int writeaccess;
+ int fault;
+ unsigned long fixup;
+ siginfo_t info;
+
+ 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.
+ *
+ * TODO: On CRIS, we have a PTE Global bit which should be set in
+ * all the PTE's related to vmalloc in all processes - that means if
+ * we switch process and a vmalloc PTE is still in the TLB, it won't
+ * need to be reloaded. It's an optimization.
+ *
+ * Linux/CRIS's kernel is not page-mapped, so the comparision below
+ * should really be >= VMALLOC_START, however, kernel fixup errors
+ * will be handled more quickly by going through vmalloc_fault and then
+ * into bad_area_nosemaphore than falling through the find_vma user-mode
+ * tests.
+ */
+
+ if (address >= TASK_SIZE)
+ goto vmalloc_fault;
+
+ mm = tsk->mm;
+ writeaccess = error_code & 2;
+ info.si_code = SEGV_MAPERR;
+
+ /*
+ * 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(&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) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ } 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.
+ */
+
+ switch (handle_mm_fault(mm, vma, address, writeaccess)) {
+ case 1:
+ tsk->min_flt++;
+ break;
+ case 2:
+ tsk->maj_flt++;
+ break;
+ case 0:
+ goto do_sigbus;
+ default:
+ goto out_of_memory;
+ }
+
+ up(&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(&mm->mmap_sem);
+
+ bad_area_nosemaphore:
+ DPG(show_registers(regs));
+
+ /* User mode accesses just cause a SIGSEGV */
+
+ if (user_mode(regs)) {
+ 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);
+ return;
+ }
+
+ no_context:
+
+ /* Are we prepared to handle this kernel fault?
+ *
+ * (The kernel has valid exception-points in the source
+ * when it acesses 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 ((fixup = search_exception_table(regs->irp)) != 0) {
+ regs->irp = fixup;
+ regs->frametype = CRIS_FRAME_FIXUP;
+ D(printk("doing fixup to 0x%x\n", fixup));
+ return;
+ }
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ 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");
+ printk(" at virtual address %08lx\n",address);
+
+ die_if_kernel("Oops", regs, error_code);
+
+ 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(&mm->mmap_sem);
+ printk("VM: killing process %s\n", tsk->comm);
+ if(user_mode(regs))
+ do_exit(SIGKILL);
+ goto no_context;
+
+ do_sigbus:
+ up(&mm->mmap_sem);
+
+ /*
+ * Send a sigbus, regardless of whether we were in kernel
+ * or user mode.
+ */
+ info.si_code = 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.
+ */
+ int offset = pgd_index(address);
+ pgd_t *pgd, *pgd_k;
+ pmd_t *pmd, *pmd_k;
+
+ pgd = tsk->active_mm->pgd + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ if (!pgd_present(*pgd)) {
+ if (!pgd_present(*pgd_k))
+ goto bad_area_nosemaphore;
+ set_pgd(pgd, *pgd_k);
+ return;
+ }
+
+ pmd = pmd_offset(pgd, address);
+ pmd_k = pmd_offset(pgd_k, address);
+
+ if (pmd_present(*pmd) || !pmd_present(*pmd_k))
+ goto bad_area_nosemaphore;
+ set_pmd(pmd, *pmd_k);
+ return;
+ }
+
+}
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