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tile: implement gettimeofday() via vDSO

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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>
This commit is contained in:
Chris Metcalf
2013-08-07 15:33:32 -04:00
parent 0c1d1917c5
commit 4a556f4f56
22 changed files with 732 additions and 62 deletions
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37
arch/tile/mm/elf.c
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@@ -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__
/*