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(fmt: "Cannot allocate vdso" ); |
28 | |
29 | vdso = vmap(pages: &vdso_page, count: 1, flags: 0, PAGE_KERNEL); |
30 | if (!vdso) |
31 | panic(fmt: "Cannot map vdso" ); |
32 | clear_page(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(addr: 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, addr: vdso_base, PAGE_SIZE, |
70 | VM_READ|VM_EXEC| |
71 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
72 | pages: &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 | |