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1da177e4 LT |
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 <asm/proto.h> | |
13 | #include <asm/tlbflush.h> | |
14 | #include <asm/ia32_unistd.h> | |
15 | ||
16 | /* 32bit VDSOs mapped into user space. */ | |
17 | asm(".section \".init.data\",\"aw\"\n" | |
18 | "syscall32_syscall:\n" | |
19 | ".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n" | |
20 | "syscall32_syscall_end:\n" | |
21 | "syscall32_sysenter:\n" | |
22 | ".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n" | |
23 | "syscall32_sysenter_end:\n" | |
24 | ".previous"); | |
25 | ||
26 | extern unsigned char syscall32_syscall[], syscall32_syscall_end[]; | |
27 | extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[]; | |
28 | extern int sysctl_vsyscall32; | |
29 | ||
30 | char *syscall32_page; | |
31 | static int use_sysenter = -1; | |
32 | ||
33 | /* | |
34 | * Map the 32bit vsyscall page on demand. | |
35 | * | |
36 | * RED-PEN: This knows too much about high level VM. | |
37 | * | |
38 | * Alternative would be to generate a vma with appropriate backing options | |
39 | * and let it be handled by generic VM. | |
40 | */ | |
41 | int __map_syscall32(struct mm_struct *mm, unsigned long address) | |
42 | { | |
43 | pgd_t *pgd; | |
44 | pud_t *pud; | |
45 | pte_t *pte; | |
46 | pmd_t *pmd; | |
47 | int err = -ENOMEM; | |
48 | ||
49 | spin_lock(&mm->page_table_lock); | |
50 | pgd = pgd_offset(mm, address); | |
51 | pud = pud_alloc(mm, pgd, address); | |
52 | if (pud) { | |
53 | pmd = pmd_alloc(mm, pud, address); | |
54 | if (pmd && (pte = pte_alloc_map(mm, pmd, address)) != NULL) { | |
55 | if (pte_none(*pte)) { | |
56 | set_pte(pte, | |
57 | mk_pte(virt_to_page(syscall32_page), | |
58 | PAGE_KERNEL_VSYSCALL32)); | |
59 | } | |
60 | /* Flush only the local CPU. Other CPUs taking a fault | |
61 | will just end up here again | |
62 | This probably not needed and just paranoia. */ | |
63 | __flush_tlb_one(address); | |
64 | err = 0; | |
65 | } | |
66 | } | |
67 | spin_unlock(&mm->page_table_lock); | |
68 | return err; | |
69 | } | |
70 | ||
71 | int map_syscall32(struct mm_struct *mm, unsigned long address) | |
72 | { | |
73 | int err; | |
74 | down_read(&mm->mmap_sem); | |
75 | err = __map_syscall32(mm, address); | |
76 | up_read(&mm->mmap_sem); | |
77 | return err; | |
78 | } | |
79 | ||
80 | static int __init init_syscall32(void) | |
81 | { | |
82 | syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); | |
83 | if (!syscall32_page) | |
84 | panic("Cannot allocate syscall32 page"); | |
85 | SetPageReserved(virt_to_page(syscall32_page)); | |
86 | if (use_sysenter > 0) { | |
87 | memcpy(syscall32_page, syscall32_sysenter, | |
88 | syscall32_sysenter_end - syscall32_sysenter); | |
89 | } else { | |
90 | memcpy(syscall32_page, syscall32_syscall, | |
91 | syscall32_syscall_end - syscall32_syscall); | |
92 | } | |
93 | return 0; | |
94 | } | |
95 | ||
96 | __initcall(init_syscall32); | |
97 | ||
98 | /* May not be __init: called during resume */ | |
99 | void syscall32_cpu_init(void) | |
100 | { | |
101 | if (use_sysenter < 0) | |
102 | use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL); | |
103 | ||
104 | /* Load these always in case some future AMD CPU supports | |
105 | SYSENTER from compat mode too. */ | |
106 | checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS); | |
107 | checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL); | |
108 | checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target); | |
109 | ||
110 | wrmsrl(MSR_CSTAR, ia32_cstar_target); | |
111 | } |