Merge master.kernel.org:/home/rmk/linux-2.6-serial
[linux-2.6] / arch / x86_64 / ia32 / syscall32.c
1 /* Copyright 2002,2003 Andi Kleen, SuSE Labs */
2
3 /* vsyscall handling for 32bit processes. Map a stub page into it 
4    on demand because 32bit cannot reach the kernel's fixmaps */
5
6 #include <linux/mm.h>
7 #include <linux/string.h>
8 #include <linux/kernel.h>
9 #include <linux/gfp.h>
10 #include <linux/init.h>
11 #include <linux/stringify.h>
12 #include <linux/security.h>
13 #include <asm/proto.h>
14 #include <asm/tlbflush.h>
15 #include <asm/ia32_unistd.h>
16
17 /* 32bit VDSOs mapped into user space. */ 
18 asm(".section \".init.data\",\"aw\"\n"
19     "syscall32_syscall:\n"
20     ".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n"
21     "syscall32_syscall_end:\n"
22     "syscall32_sysenter:\n"
23     ".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n"
24     "syscall32_sysenter_end:\n"
25     ".previous");
26
27 extern unsigned char syscall32_syscall[], syscall32_syscall_end[];
28 extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[];
29 extern int sysctl_vsyscall32;
30
31 char *syscall32_page; 
32 static int use_sysenter = -1;
33
34 static struct page *
35 syscall32_nopage(struct vm_area_struct *vma, unsigned long adr, int *type)
36 {
37         struct page *p = virt_to_page(adr - vma->vm_start + syscall32_page);
38         get_page(p);
39         return p;
40 }
41
42 /* Prevent VMA merging */
43 static void syscall32_vma_close(struct vm_area_struct *vma)
44 {
45 }
46
47 static struct vm_operations_struct syscall32_vm_ops = {
48         .close = syscall32_vma_close,
49         .nopage = syscall32_nopage,
50 };
51
52 struct linux_binprm;
53
54 /* Setup a VMA at program startup for the vsyscall page */
55 int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
56 {
57         int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
58         struct vm_area_struct *vma;
59         struct mm_struct *mm = current->mm;
60         int ret;
61
62         vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
63         if (!vma)
64                 return -ENOMEM;
65         if (security_vm_enough_memory(npages)) {
66                 kmem_cache_free(vm_area_cachep, vma);
67                 return -ENOMEM;
68         }
69
70         memset(vma, 0, sizeof(struct vm_area_struct));
71         /* Could randomize here */
72         vma->vm_start = VSYSCALL32_BASE;
73         vma->vm_end = VSYSCALL32_END;
74         /* MAYWRITE to allow gdb to COW and set breakpoints */
75         vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYEXEC|VM_MAYWRITE;
76         vma->vm_flags |= mm->def_flags;
77         vma->vm_page_prot = protection_map[vma->vm_flags & 7];
78         vma->vm_ops = &syscall32_vm_ops;
79         vma->vm_mm = mm;
80
81         down_write(&mm->mmap_sem);
82         if ((ret = insert_vm_struct(mm, vma))) {
83                 up_write(&mm->mmap_sem);
84                 kmem_cache_free(vm_area_cachep, vma);
85                 return ret;
86         }
87         mm->total_vm += npages;
88         up_write(&mm->mmap_sem);
89         return 0;
90 }
91
92 static int __init init_syscall32(void)
93
94         syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); 
95         if (!syscall32_page) 
96                 panic("Cannot allocate syscall32 page"); 
97         if (use_sysenter > 0) {
98                 memcpy(syscall32_page, syscall32_sysenter,
99                        syscall32_sysenter_end - syscall32_sysenter);
100         } else {
101                 memcpy(syscall32_page, syscall32_syscall,
102                        syscall32_syscall_end - syscall32_syscall);
103         }       
104         return 0;
105
106         
107 __initcall(init_syscall32); 
108
109 /* May not be __init: called during resume */
110 void syscall32_cpu_init(void)
111 {
112         if (use_sysenter < 0)
113                 use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL);
114
115         /* Load these always in case some future AMD CPU supports
116            SYSENTER from compat mode too. */
117         checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
118         checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL);
119         checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
120
121         wrmsrl(MSR_CSTAR, ia32_cstar_target);
122 }