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08dbd0f8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
cd5b61d6 RK |
2 | /* |
3 | * vDSO implementation for Hexagon | |
4 | * | |
e1858b2a | 5 | * Copyright (c) 2011, The Linux Foundation. All rights reserved. |
cd5b61d6 RK |
6 | */ |
7 | ||
8 | #include <linux/err.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/vmalloc.h> | |
6bbbc30c | 11 | #include <linux/binfmts.h> |
cd5b61d6 RK |
12 | |
13 | #include <asm/vdso.h> | |
14 | ||
15 | static struct page *vdso_page; | |
16 | ||
17 | /* Create a vDSO page holding the signal trampoline. | |
18 | * We want this for a non-executable stack. | |
19 | */ | |
20 | static int __init vdso_init(void) | |
21 | { | |
22 | struct hexagon_vdso *vdso; | |
23 | ||
24 | vdso_page = alloc_page(GFP_KERNEL); | |
25 | if (!vdso_page) | |
26 | panic("Cannot allocate vdso"); | |
27 | ||
28 | vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL); | |
29 | if (!vdso) | |
30 | panic("Cannot map vdso"); | |
31 | clear_page(vdso); | |
32 | ||
33 | /* Install the signal trampoline; currently looks like this: | |
34 | * r6 = #__NR_rt_sigreturn; | |
35 | * trap0(#1); | |
36 | */ | |
37 | vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0]; | |
38 | vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1]; | |
39 | ||
40 | vunmap(vdso); | |
41 | ||
42 | return 0; | |
43 | } | |
44 | arch_initcall(vdso_init); | |
45 | ||
46 | /* | |
47 | * Called from binfmt_elf. Create a VMA for the vDSO page. | |
48 | */ | |
49 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) | |
50 | { | |
51 | int ret; | |
52 | unsigned long vdso_base; | |
53 | struct mm_struct *mm = current->mm; | |
54 | ||
69048176 MH |
55 | if (down_write_killable(&mm->mmap_sem)) |
56 | return -EINTR; | |
cd5b61d6 RK |
57 | |
58 | /* Try to get it loaded right near ld.so/glibc. */ | |
59 | vdso_base = STACK_TOP; | |
60 | ||
61 | vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0); | |
62 | if (IS_ERR_VALUE(vdso_base)) { | |
63 | ret = vdso_base; | |
64 | goto up_fail; | |
65 | } | |
66 | ||
67 | /* MAYWRITE to allow gdb to COW and set breakpoints. */ | |
68 | ret = install_special_mapping(mm, vdso_base, PAGE_SIZE, | |
69 | VM_READ|VM_EXEC| | |
909af768 | 70 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
cd5b61d6 RK |
71 | &vdso_page); |
72 | ||
73 | if (ret) | |
74 | goto up_fail; | |
75 | ||
76 | mm->context.vdso = (void *)vdso_base; | |
77 | ||
78 | up_fail: | |
79 | up_write(&mm->mmap_sem); | |
80 | return ret; | |
81 | } | |
82 | ||
83 | const char *arch_vma_name(struct vm_area_struct *vma) | |
84 | { | |
85 | if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) | |
86 | return "[vdso]"; | |
87 | return NULL; | |
88 | } |