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>
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
new file mode 100644
index 0000000..c10b76f
--- /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);
+}