Hexagon: Add page-fault support.

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Linas Vepstas <linas@codeaurora.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 187 insertions, 0 deletions

diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
new file mode 100644
index 000000000000..c10b76ff9d65
--- /dev/null
+++ b/arch/hexagon/mm/vm_fault.c
@@ -0,0 +1,187 @@
+/*
+ * Memory fault handling for Hexagon
+ *
+ * Copyright (c) 2010-2011 Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/*
+ * Page fault handling for the Hexagon Virtual Machine.
+ * Can also be called by a native port emulating the HVM
+ * execptions.
+ */
+
+#include <asm/pgtable.h>
+#include <asm/traps.h>
+#include <asm/uaccess.h>
+#include <linux/mm.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/hardirq.h>
+
+/*
+ * Decode of hardware exception sends us to one of several
+ * entry points.  At each, we generate canonical arguments
+ * for handling by the abstract memory management code.
+ */
+#define FLT_IFETCH     -1
+#define FLT_LOAD        0
+#define FLT_STORE       1
+
+
+/*
+ * Canonical page fault handler
+ */
+void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
+{
+        struct vm_area_struct *vma;
+        struct mm_struct *mm = current->mm;
+        siginfo_t info;
+        int si_code = SEGV_MAPERR;
+        int fault;
+        const struct exception_table_entry *fixup;
+
+        /*
+         * If we're in an interrupt or have no user context,
+         * then must not take the fault.
+         */
+        if (unlikely(in_interrupt() || !mm))
+                goto no_context;
+
+        local_irq_enable();
+
+        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;
+
+good_area:
+        /* Address space is OK.  Now check access rights. */
+        si_code = SEGV_ACCERR;
+
+        switch (cause) {
+        case FLT_IFETCH:
+                if (!(vma->vm_flags & VM_EXEC))
+                        goto bad_area;
+                break;
+        case FLT_LOAD:
+                if (!(vma->vm_flags & VM_READ))
+                        goto bad_area;
+                break;
+        case FLT_STORE:
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+                break;
+        }
+
+        fault = handle_mm_fault(mm, vma, address, (cause > 0));
+
+        /* The most common case -- we are done. */
+        if (likely(!(fault & VM_FAULT_ERROR))) {
+                if (fault & VM_FAULT_MAJOR)
+                        current->maj_flt++;
+                else
+                        current->min_flt++;
+
+                up_read(&mm->mmap_sem);
+                return;
+        }
+
+        up_read(&mm->mmap_sem);
+
+        /* Handle copyin/out exception cases */
+        if (!user_mode(regs))
+                goto no_context;
+
+        if (fault & VM_FAULT_OOM) {
+                pagefault_out_of_memory();
+                return;
+        }
+
+        /* User-mode address is in the memory map, but we are
+         * unable to fix up the page fault.
+         */
+        if (fault & VM_FAULT_SIGBUS) {
+                info.si_signo = SIGBUS;
+                info.si_code = BUS_ADRERR;
+        }
+        /* Address is not in the memory map */
+        else {
+                info.si_signo = SIGSEGV;
+                info.si_code = SEGV_ACCERR;
+        }
+        info.si_errno = 0;
+        info.si_addr = (void __user *)address;
+        force_sig_info(info.si_code, &info, current);
+        return;
+
+bad_area:
+        up_read(&mm->mmap_sem);
+
+        if (user_mode(regs)) {
+                info.si_signo = SIGSEGV;
+                info.si_errno = 0;
+                info.si_code = si_code;
+                info.si_addr = (void *)address;
+                force_sig_info(SIGSEGV, &info, current);
+                return;
+        }
+        /* Kernel-mode fault falls through */
+
+no_context:
+        fixup = search_exception_tables(pt_elr(regs));
+        if (fixup) {
+                pt_set_elr(regs, fixup->fixup);
+                return;
+        }
+
+        /* Things are looking very, very bad now */
+        bust_spinlocks(1);
+        printk(KERN_EMERG "Unable to handle kernel paging request at "
+                "virtual address 0x%08lx, regs %p\n", address, regs);
+        die("Bad Kernel VA", regs, SIGKILL);
+}
+
+
+void read_protection_fault(struct pt_regs *regs)
+{
+        unsigned long badvadr = pt_badva(regs);
+
+        do_page_fault(badvadr, FLT_LOAD, regs);
+}
+
+void write_protection_fault(struct pt_regs *regs)
+{
+        unsigned long badvadr = pt_badva(regs);
+
+        do_page_fault(badvadr, FLT_STORE, regs);
+}
+
+void execute_protection_fault(struct pt_regs *regs)
+{
+        unsigned long badvadr = pt_badva(regs);
+
+        do_page_fault(badvadr, FLT_IFETCH, regs);
+}