1 files changed, 251 insertions, 0 deletions
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
new file mode 100644
index 0000000000..5458b52b40
--- /dev/null
+++ b/arch/ia64/mm/fault.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MMU fault handling support.
+ *
+ * Copyright (C) 1998-2002 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+#include <linux/sched/signal.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/extable.h>
+#include <linux/interrupt.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/prefetch.h>
+#include <linux/uaccess.h>
+#include <linux/perf_event.h>
+
+#include <asm/processor.h>
+#include <asm/exception.h>
+
+extern int die(char *, struct pt_regs *, long);
+
+/*
+ * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
+ * (inside region 5, on ia64) and that page is present.
+ */
+static int
+mapped_kernel_page_is_present (unsigned long address)
+{
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *ptep, pte;
+
+	pgd = pgd_offset_k(address);
+	if (pgd_none(*pgd) || pgd_bad(*pgd))
+		return 0;
+
+	p4d = p4d_offset(pgd, address);
+	if (p4d_none(*p4d) || p4d_bad(*p4d))
+		return 0;
+
+	pud = pud_offset(p4d, address);
+	if (pud_none(*pud) || pud_bad(*pud))
+		return 0;
+
+	pmd = pmd_offset(pud, address);
+	if (pmd_none(*pmd) || pmd_bad(*pmd))
+		return 0;
+
+	ptep = pte_offset_kernel(pmd, address);
+	if (!ptep)
+		return 0;
+
+	pte = *ptep;
+	return pte_present(pte);
+}
+
+#	define VM_READ_BIT	0
+#	define VM_WRITE_BIT	1
+#	define VM_EXEC_BIT	2
+
+void __kprobes
+ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
+{
+	int signal = SIGSEGV, code = SEGV_MAPERR;
+	struct vm_area_struct *vma, *prev_vma;
+	struct mm_struct *mm = current->mm;
+	unsigned long mask;
+	vm_fault_t fault;
+	unsigned int flags = FAULT_FLAG_DEFAULT;
+
+	mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
+		| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
+
+	/* mmap_lock is performance critical.... */
+	prefetchw(&mm->mmap_lock);
+
+	/*
+	 * If we're in an interrupt or have no user context, we must not take the fault..
+	 */
+	if (faulthandler_disabled() || !mm)
+		goto no_context;
+
+	/*
+	 * This is to handle the kprobes on user space access instructions
+	 */
+	if (kprobe_page_fault(regs, TRAP_BRKPT))
+		return;
+
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (mask & VM_WRITE)
+		flags |= FAULT_FLAG_WRITE;
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+retry:
+	mmap_read_lock(mm);
+
+	vma = find_vma_prev(mm, address, &prev_vma);
+	if (!vma && !prev_vma )
+		goto bad_area;
+
+        /*
+         * find_vma_prev() returns vma such that address < vma->vm_end or NULL
+         *
+         * May find no vma, but could be that the last vm area is the
+         * register backing store that needs to expand upwards, in
+         * this case vma will be null, but prev_vma will ne non-null
+         */
+        if (( !vma && prev_vma ) || (address < vma->vm_start) ) {
+		vma = expand_stack(mm, address);
+		if (!vma)
+			goto bad_area_nosemaphore;
+	}
+
+	code = SEGV_ACCERR;
+
+	/* OK, we've got a good vm_area for this memory area.  Check the access permissions: */
+
+#	if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
+	    || (1 << VM_EXEC_BIT) != VM_EXEC)
+#		error File is out of sync with <linux/mm.h>.  Please update.
+#	endif
+
+	if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
+		goto bad_area;
+
+	if ((vma->vm_flags & mask) != mask)
+		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, regs);
+
+	if (fault_signal_pending(fault, regs)) {
+		if (!user_mode(regs))
+			goto no_context;
+		return;
+	}
+
+	/* The fault is fully completed (including releasing mmap lock) */
+	if (fault & VM_FAULT_COMPLETED)
+		return;
+
+	if (unlikely(fault & VM_FAULT_ERROR)) {
+		/*
+		 * We ran out of memory, or some other thing happened
+		 * to us that made us unable to handle the page fault
+		 * gracefully.
+		 */
+		if (fault & VM_FAULT_OOM) {
+			goto out_of_memory;
+		} else if (fault & VM_FAULT_SIGSEGV) {
+			goto bad_area;
+		} else if (fault & VM_FAULT_SIGBUS) {
+			signal = SIGBUS;
+			goto bad_area;
+		}
+		BUG();
+	}
+
+	if (fault & VM_FAULT_RETRY) {
+		flags |= FAULT_FLAG_TRIED;
+
+		/* No need to mmap_read_unlock(mm) as we would
+		 * have already released it in __lock_page_or_retry
+		 * in mm/filemap.c.
+		 */
+
+		goto retry;
+	}
+
+	mmap_read_unlock(mm);
+	return;
+
+  bad_area:
+	mmap_read_unlock(mm);
+  bad_area_nosemaphore:
+	if ((isr & IA64_ISR_SP)
+	    || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
+	{
+		/*
+		 * This fault was due to a speculative load or lfetch.fault, set the "ed"
+		 * bit in the psr to ensure forward progress.  (Target register will get a
+		 * NaT for ld.s, lfetch will be canceled.)
+		 */
+		ia64_psr(regs)->ed = 1;
+		return;
+	}
+	if (user_mode(regs)) {
+		force_sig_fault(signal, code, (void __user *) address,
+				0, __ISR_VALID, isr);
+		return;
+	}
+
+  no_context:
+	if ((isr & IA64_ISR_SP)
+	    || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
+	{
+		/*
+		 * This fault was due to a speculative load or lfetch.fault, set the "ed"
+		 * bit in the psr to ensure forward progress.  (Target register will get a
+		 * NaT for ld.s, lfetch will be canceled.)
+		 */
+		ia64_psr(regs)->ed = 1;
+		return;
+	}
+
+	/*
+	 * Since we have no vma's for region 5, we might get here even if the address is
+	 * valid, due to the VHPT walker inserting a non present translation that becomes
+	 * stale. If that happens, the non present fault handler already purged the stale
+	 * translation, which fixed the problem. So, we check to see if the translation is
+	 * valid, and return if it is.
+	 */
+	if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
+		return;
+
+	if (ia64_done_with_exception(regs))
+		return;
+
+	/*
+	 * Oops. The kernel tried to access some bad page. We'll have to terminate things
+	 * with extreme prejudice.
+	 */
+	bust_spinlocks(1);
+
+	if (address < PAGE_SIZE)
+		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
+	else
+		printk(KERN_ALERT "Unable to handle kernel paging request at "
+		       "virtual address %016lx\n", address);
+	if (die("Oops", regs, isr))
+		regs = NULL;
+	bust_spinlocks(0);
+	if (regs)
+		make_task_dead(SIGKILL);
+	return;
+
+  out_of_memory:
+	mmap_read_unlock(mm);
+	if (!user_mode(regs))
+		goto no_context;
+	pagefault_out_of_memory();
+}