1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * vDSO implementation for Hexagon
4 *
5 * Copyright (c) 2011, The Linux Foundation. All rights reserved.
6 */
7
8 #include <linux/err.h>
9 #include <linux/mm.h>
10 #include <linux/vmalloc.h>
11 #include <linux/binfmts.h>
12
13 #include <asm/elf.h>
14 #include <asm/vdso.h>
15
16 static struct page *vdso_page;
17
18 /* Create a vDSO page holding the signal trampoline.
19 * We want this for a non-executable stack.
20 */
21 static int __init vdso_init(void)
22 {
23 struct hexagon_vdso *vdso;
24
25 vdso_page = alloc_page(GFP_KERNEL);
26 if (!vdso_page)
27 panic("Cannot allocate vdso");
28
29 vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
30 if (!vdso)
31 panic("Cannot map vdso");
32 clear_page(vdso);
33
34 /* Install the signal trampoline; currently looks like this:
35 * r6 = #__NR_rt_sigreturn;
36 * trap0(#1);
37 */
38 vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
39 vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];
40
41 vunmap(vdso);
42
43 return 0;
44 }
45 arch_initcall(vdso_init);
46
47 /*
48 * Called from binfmt_elf. Create a VMA for the vDSO page.
49 */
50 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
51 {
52 int ret;
53 unsigned long vdso_base;
54 struct mm_struct *mm = current->mm;
55
56 if (mmap_write_lock_killable(mm))
57 return -EINTR;
58
59 /* Try to get it loaded right near ld.so/glibc. */
60 vdso_base = STACK_TOP;
61
62 vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
63 if (IS_ERR_VALUE(vdso_base)) {
64 ret = vdso_base;
65 goto up_fail;
66 }
67
68 /* MAYWRITE to allow gdb to COW and set breakpoints. */
69 ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
70 VM_READ|VM_EXEC|
71 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
72 &vdso_page);
73
74 if (ret)
75 goto up_fail;
76
77 mm->context.vdso = (void *)vdso_base;
78
79 up_fail:
80 mmap_write_unlock(mm);
81 return ret;
82 }
83
84 const char *arch_vma_name(struct vm_area_struct *vma)
85 {
86 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
87 return "[vdso]";
88 return NULL;
89 }
90
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.