xref: /openbmc/linux/arch/mips/kernel/vdso.c (revision b34e08d5)
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2009, 2010 Cavium Networks, Inc.
7  */
8 
9 
10 #include <linux/kernel.h>
11 #include <linux/err.h>
12 #include <linux/sched.h>
13 #include <linux/mm.h>
14 #include <linux/init.h>
15 #include <linux/binfmts.h>
16 #include <linux/elf.h>
17 #include <linux/vmalloc.h>
18 #include <linux/unistd.h>
19 
20 #include <asm/vdso.h>
21 #include <asm/uasm.h>
22 
23 /*
24  * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
25  */
26 #define __NR_O32_sigreturn		4119
27 #define __NR_O32_rt_sigreturn		4193
28 #define __NR_N32_rt_sigreturn		6211
29 
30 static struct page *vdso_page;
31 
32 static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
33 {
34 	uasm_i_addiu(&tramp, 2, 0, sigreturn);	/* li v0, sigreturn */
35 	uasm_i_syscall(&tramp, 0);
36 }
37 
38 static int __init init_vdso(void)
39 {
40 	struct mips_vdso *vdso;
41 
42 	vdso_page = alloc_page(GFP_KERNEL);
43 	if (!vdso_page)
44 		panic("Cannot allocate vdso");
45 
46 	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
47 	if (!vdso)
48 		panic("Cannot map vdso");
49 	clear_page(vdso);
50 
51 	install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
52 #ifdef CONFIG_32BIT
53 	install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
54 #else
55 	install_trampoline(vdso->n32_rt_signal_trampoline,
56 			   __NR_N32_rt_sigreturn);
57 	install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
58 	install_trampoline(vdso->o32_rt_signal_trampoline,
59 			   __NR_O32_rt_sigreturn);
60 #endif
61 
62 	vunmap(vdso);
63 
64 	return 0;
65 }
66 subsys_initcall(init_vdso);
67 
68 static unsigned long vdso_addr(unsigned long start)
69 {
70 	return STACK_TOP;
71 }
72 
73 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
74 {
75 	int ret;
76 	unsigned long addr;
77 	struct mm_struct *mm = current->mm;
78 
79 	down_write(&mm->mmap_sem);
80 
81 	addr = vdso_addr(mm->start_stack);
82 
83 	addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
84 	if (IS_ERR_VALUE(addr)) {
85 		ret = addr;
86 		goto up_fail;
87 	}
88 
89 	ret = install_special_mapping(mm, addr, PAGE_SIZE,
90 				      VM_READ|VM_EXEC|
91 				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
92 				      &vdso_page);
93 
94 	if (ret)
95 		goto up_fail;
96 
97 	mm->context.vdso = (void *)addr;
98 
99 up_fail:
100 	up_write(&mm->mmap_sem);
101 	return ret;
102 }
103 
104 const char *arch_vma_name(struct vm_area_struct *vma)
105 {
106 	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
107 		return "[vdso]";
108 	return NULL;
109 }
110