| /* |
| * 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, |
| &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; |
| } |