tile: implement gettimeofday() via vDSO

This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)

Note that glibc has supported the tile vDSO since release 2.17.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 2 insertions, 35 deletions

diff --git a/arch/tile/mm/elf.c b/arch/tile/mm/elf.c
index 1691b81b2b0c..23f044e8a7ab 100644
--- a/arch/tile/mm/elf.c
+++ b/arch/tile/mm/elf.c
@@ -21,6 +21,7 @@
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
+#include <asm/vdso.h>
 #include <arch/sim.h>
 
 /* Notify a running simulator, if any, that an exec just occurred. */
@@ -102,37 +103,10 @@ static void sim_notify_interp(unsigned long load_addr)
 }
 
 
-/* Kernel address of page used to map read-only kernel data into userspace. */
-static void *vdso_page;
-
-/* One-entry array used for install_special_mapping. */
-static struct page *vdso_pages[1];
-
-static int __init vdso_setup(void)
-{
-        vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
-        memcpy(vdso_page, __rt_sigreturn, __rt_sigreturn_end - __rt_sigreturn);
-        vdso_pages[0] = virt_to_page(vdso_page);
-        return 0;
-}
-device_initcall(vdso_setup);
-
-const char *arch_vma_name(struct vm_area_struct *vma)
-{
-        if (vma->vm_private_data == vdso_pages)
-                return "[vdso]";
-#ifndef __tilegx__
-        if (vma->vm_start == MEM_USER_INTRPT)
-                return "[intrpt]";
-#endif
-        return NULL;
-}
-
 int arch_setup_additional_pages(struct linux_binprm *bprm,
                                 int executable_stack)
 {
         struct mm_struct *mm = current->mm;
-        unsigned long vdso_base;
         int retval = 0;
 
         down_write(&mm->mmap_sem);
@@ -145,14 +119,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         if (!notify_exec(mm))
                 sim_notify_exec(bprm->filename);
 
-        /*
-         * MAYWRITE to allow gdb to COW and set breakpoints
-         */
-        vdso_base = VDSO_BASE;
-        retval = install_special_mapping(mm, vdso_base, PAGE_SIZE,
-                                         VM_READ|VM_EXEC|
-                                         VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-                                         vdso_pages);
+        retval = setup_vdso_pages();
 
 #ifndef __tilegx__
         /*