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git.proxmox.com Git - mirror_ubuntu-kernels.git/blob - arch/x86/kernel/tls.c
1 #include <linux/kernel.h>
2 #include <linux/errno.h>
3 #include <linux/sched.h>
4 #include <linux/user.h>
6 #include <asm/uaccess.h>
8 #include <asm/system.h>
10 #include <asm/processor.h>
11 #include <asm/proto.h>
14 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
16 static int get_free_idx(void)
18 struct thread_struct
*t
= ¤t
->thread
;
21 for (idx
= 0; idx
< GDT_ENTRY_TLS_ENTRIES
; idx
++)
22 if (desc_empty(&t
->tls_array
[idx
]))
23 return idx
+ GDT_ENTRY_TLS_MIN
;
28 * Set a given TLS descriptor:
30 int do_set_thread_area(struct task_struct
*p
, int idx
,
31 struct user_desc __user
*u_info
,
34 struct thread_struct
*t
= &p
->thread
;
35 struct user_desc info
;
39 if (copy_from_user(&info
, u_info
, sizeof(info
)))
43 idx
= info
.entry_number
;
46 * index -1 means the kernel should try to find and
47 * allocate an empty descriptor:
49 if (idx
== -1 && can_allocate
) {
53 if (put_user(idx
, &u_info
->entry_number
))
57 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
60 desc
= (u32
*) &t
->tls_array
[idx
- GDT_ENTRY_TLS_MIN
];
63 * We must not get preempted while modifying the TLS.
67 if (LDT_empty(&info
)) {
71 desc
[0] = LDT_entry_a(&info
);
72 desc
[1] = LDT_entry_b(&info
);
74 if (t
== ¤t
->thread
)
81 asmlinkage
int sys_set_thread_area(struct user_desc __user
*u_info
)
83 return do_set_thread_area(current
, -1, u_info
, 1);
88 * Get the current Thread-Local Storage area:
91 #define GET_LIMIT(desc) (((desc)[0] & 0x0ffff) | ((desc)[1] & 0xf0000))
92 #define GET_32BIT(desc) (((desc)[1] >> 22) & 1)
93 #define GET_CONTENTS(desc) (((desc)[1] >> 10) & 3)
94 #define GET_WRITABLE(desc) (((desc)[1] >> 9) & 1)
95 #define GET_LIMIT_PAGES(desc) (((desc)[1] >> 23) & 1)
96 #define GET_PRESENT(desc) (((desc)[1] >> 15) & 1)
97 #define GET_USEABLE(desc) (((desc)[1] >> 20) & 1)
98 #define GET_LONGMODE(desc) (((desc)[1] >> 21) & 1)
100 int do_get_thread_area(struct task_struct
*p
, int idx
,
101 struct user_desc __user
*u_info
)
103 struct thread_struct
*t
= &p
->thread
;
104 struct user_desc info
;
107 if (idx
== -1 && get_user(idx
, &u_info
->entry_number
))
109 if (idx
< GDT_ENTRY_TLS_MIN
|| idx
> GDT_ENTRY_TLS_MAX
)
112 desc
= (u32
*) &t
->tls_array
[idx
- GDT_ENTRY_TLS_MIN
];
114 memset(&info
, 0, sizeof(struct user_desc
));
115 info
.entry_number
= idx
;
116 info
.base_addr
= get_desc_base((void *)desc
);
117 info
.limit
= GET_LIMIT(desc
);
118 info
.seg_32bit
= GET_32BIT(desc
);
119 info
.contents
= GET_CONTENTS(desc
);
120 info
.read_exec_only
= !GET_WRITABLE(desc
);
121 info
.limit_in_pages
= GET_LIMIT_PAGES(desc
);
122 info
.seg_not_present
= !GET_PRESENT(desc
);
123 info
.useable
= GET_USEABLE(desc
);
125 info
.lm
= GET_LONGMODE(desc
);
128 if (copy_to_user(u_info
, &info
, sizeof(info
)))
133 asmlinkage
int sys_get_thread_area(struct user_desc __user
*u_info
)
135 return do_get_thread_area(current
, -1, u_info
);