| Richard Kuo | cd5b61d | 2011-10-31 18:41:21 -0500 | [diff] [blame] | 1 | /* |
| 2 | * vDSO implementation for Hexagon |
| 3 | * |
| 4 | * Copyright (c) 2011, Code Aurora Forum. All rights reserved. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 and |
| 8 | * only version 2 as published by the Free Software Foundation. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 18 | * 02110-1301, USA. |
| 19 | */ |
| 20 | |
| 21 | #include <linux/err.h> |
| 22 | #include <linux/mm.h> |
| 23 | #include <linux/vmalloc.h> |
| 24 | |
| 25 | #include <asm/vdso.h> |
| 26 | |
| 27 | static struct page *vdso_page; |
| 28 | |
| 29 | /* Create a vDSO page holding the signal trampoline. |
| 30 | * We want this for a non-executable stack. |
| 31 | */ |
| 32 | static int __init vdso_init(void) |
| 33 | { |
| 34 | struct hexagon_vdso *vdso; |
| 35 | |
| 36 | vdso_page = alloc_page(GFP_KERNEL); |
| 37 | if (!vdso_page) |
| 38 | panic("Cannot allocate vdso"); |
| 39 | |
| 40 | vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL); |
| 41 | if (!vdso) |
| 42 | panic("Cannot map vdso"); |
| 43 | clear_page(vdso); |
| 44 | |
| 45 | /* Install the signal trampoline; currently looks like this: |
| 46 | * r6 = #__NR_rt_sigreturn; |
| 47 | * trap0(#1); |
| 48 | */ |
| 49 | vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0]; |
| 50 | vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1]; |
| 51 | |
| 52 | vunmap(vdso); |
| 53 | |
| 54 | return 0; |
| 55 | } |
| 56 | arch_initcall(vdso_init); |
| 57 | |
| 58 | /* |
| 59 | * Called from binfmt_elf. Create a VMA for the vDSO page. |
| 60 | */ |
| 61 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| 62 | { |
| 63 | int ret; |
| 64 | unsigned long vdso_base; |
| 65 | struct mm_struct *mm = current->mm; |
| 66 | |
| 67 | down_write(&mm->mmap_sem); |
| 68 | |
| 69 | /* Try to get it loaded right near ld.so/glibc. */ |
| 70 | vdso_base = STACK_TOP; |
| 71 | |
| 72 | vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0); |
| 73 | if (IS_ERR_VALUE(vdso_base)) { |
| 74 | ret = vdso_base; |
| 75 | goto up_fail; |
| 76 | } |
| 77 | |
| 78 | /* MAYWRITE to allow gdb to COW and set breakpoints. */ |
| 79 | ret = install_special_mapping(mm, vdso_base, PAGE_SIZE, |
| 80 | VM_READ|VM_EXEC| |
| 81 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| |
| 82 | VM_ALWAYSDUMP, |
| 83 | &vdso_page); |
| 84 | |
| 85 | if (ret) |
| 86 | goto up_fail; |
| 87 | |
| 88 | mm->context.vdso = (void *)vdso_base; |
| 89 | |
| 90 | up_fail: |
| 91 | up_write(&mm->mmap_sem); |
| 92 | return ret; |
| 93 | } |
| 94 | |
| 95 | const char *arch_vma_name(struct vm_area_struct *vma) |
| 96 | { |
| 97 | if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) |
| 98 | return "[vdso]"; |
| 99 | return NULL; |
| 100 | } |