Hexagon: Add signal functions

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, 100 insertions, 0 deletions

diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c
new file mode 100644
index 000000000000..16277c33308a
--- /dev/null
+++ b/arch/hexagon/kernel/vdso.c
@@ -0,0 +1,100 @@
+/*
+ * vDSO implementation for Hexagon
+ *
+ * Copyright (c) 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.
+ */
+
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+
+#include <asm/vdso.h>
+
+static struct page *vdso_page;
+
+/* Create a vDSO page holding the signal trampoline.
+ * We want this for a non-executable stack.
+ */
+static int __init vdso_init(void)
+{
+        struct hexagon_vdso *vdso;
+
+        vdso_page = alloc_page(GFP_KERNEL);
+        if (!vdso_page)
+                panic("Cannot allocate vdso");
+
+        vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
+        if (!vdso)
+                panic("Cannot map vdso");
+        clear_page(vdso);
+
+        /* Install the signal trampoline; currently looks like this:
+         *      r6 = #__NR_rt_sigreturn;
+         *      trap0(#1);
+         */
+        vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
+        vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];
+
+        vunmap(vdso);
+
+        return 0;
+}
+arch_initcall(vdso_init);
+
+/*
+ * Called from binfmt_elf.  Create a VMA for the vDSO page.
+ */
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+        int ret;
+        unsigned long vdso_base;
+        struct mm_struct *mm = current->mm;
+
+        down_write(&mm->mmap_sem);
+
+        /* Try to get it loaded right near ld.so/glibc. */
+        vdso_base = STACK_TOP;
+
+        vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
+        if (IS_ERR_VALUE(vdso_base)) {
+                ret = vdso_base;
+                goto up_fail;
+        }
+
+        /* MAYWRITE to allow gdb to COW and set breakpoints. */
+        ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+                                      VM_READ|VM_EXEC|
+                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+                                      VM_ALWAYSDUMP,
+                                      &vdso_page);
+
+        if (ret)
+                goto up_fail;
+
+        mm->context.vdso = (void *)vdso_base;
+
+up_fail:
+        up_write(&mm->mmap_sem);
+        return ret;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+        if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
+                return "[vdso]";
+        return NULL;
+}