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/*
* vDSO implementation for Hexagon
*
* Copyright (c) 2011, The Linux Foundation. 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 <linux/binfmts.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,
&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;
}
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