1 /* Definitions for thread-local data handling. Hurd/i386 version.
2 Copyright (C) 2003-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
23 /* Some things really need not be machine-dependent. */
24 #include <sysdeps/mach/hurd/tls.h>
30 /* Type of the TCB. */
33 void *tcb
; /* Points to this structure. */
34 dtv_t
*dtv
; /* Vector of pointers to TLS data. */
35 thread_t self
; /* This thread's control port. */
38 uintptr_t stack_guard
;
39 uintptr_t pointer_guard
;
42 /* Reservation of some values for the TM ABI. */
43 void *__private_tm
[4];
44 /* GCC split stack support. */
50 /* The TCB can have any size and the memory following the address the
51 thread pointer points to is unspecified. Allocate the TCB there. */
52 #define TLS_TCB_AT_TP 1
53 #define TLS_DTV_AT_TP 0
57 /* Use i386-specific RPCs to arrange that %gs segment register prefix
58 addresses the TCB in each thread. */
59 # include <mach/i386/mach_i386.h>
61 # ifndef HAVE_I386_SET_GDT
62 # define __i386_set_gdt(thr, sel, desc) ((void) (thr), (void) (sel), (void) (desc), MIG_BAD_ID)
68 # define HURD_TLS_DESC_DECL(desc, tcb) \
69 struct descriptor desc = \
71 0xffff /* limit 0..15 */ \
72 | (((unsigned int) (tcb)) << 16) /* base 0..15 */ \
74 ((((unsigned int) (tcb)) >> 16) & 0xff) /* base 16..23 */ \
75 | ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */ \
76 | (0xf << 16) /* limit 16..19 */ \
77 | ((4 | 8) << 20) /* granularity = SZ_32|SZ_G */ \
78 | (((unsigned int) (tcb)) & 0xff000000) /* base 24..31 */ \
82 static inline const char * __attribute__ ((unused
))
83 _hurd_tls_init (tcbhead_t
*tcb
)
85 HURD_TLS_DESC_DECL (desc
, tcb
);
87 /* This field is used by TLS accesses to get our "thread pointer"
88 from the TLS point of view. */
91 /* Cache our thread port. */
92 tcb
->self
= __mach_thread_self ();
94 /* Get the first available selector. */
96 error_t err
= __i386_set_gdt (tcb
->self
, &sel
, desc
);
97 if (err
== MIG_BAD_ID
)
99 /* Old kernel, use a per-thread LDT. */
101 err
= __i386_set_ldt (tcb
->self
, sel
, &desc
, 1);
104 return "i386_set_ldt failed";
108 assert_perror (err
); /* Separate from above with different line #. */
109 return "i386_set_gdt failed";
112 /* Now install the new selector. */
113 asm volatile ("mov %w0, %%gs" :: "q" (sel
));
118 /* Code to initially initialize the thread pointer. This might need
119 special attention since 'errno' is not yet available and if the
120 operation can cause a failure 'errno' must not be touched. */
121 # define TLS_INIT_TP(descr) \
122 _hurd_tls_init ((tcbhead_t *) (descr))
124 /* Return the TCB address of the current thread. */
125 # define THREAD_SELF \
126 ({ tcbhead_t *__tcb; \
127 __asm__ ("movl %%gs:%c1,%0" : "=r" (__tcb) \
128 : "i" (offsetof (tcbhead_t, tcb))); \
131 /* Install new dtv for current thread. */
132 # define INSTALL_NEW_DTV(dtvp) \
133 ({ asm volatile ("movl %0,%%gs:%P1" \
134 : : "ir" (dtvp), "i" (offsetof (tcbhead_t, dtv))); })
136 /* Return the address of the dtv for the current thread. */
137 # define THREAD_DTV() \
139 asm ("movl %%gs:%P1,%0" : "=q" (_dtv) : "i" (offsetof (tcbhead_t, dtv)));\
142 # include <mach/machine/thread_status.h>
144 /* Set up TLS in the new thread of a fork child, copying from our own. */
145 static inline error_t
__attribute__ ((unused
))
146 _hurd_tls_fork (thread_t child
, struct i386_thread_state
*state
)
148 /* Fetch the selector set by _hurd_tls_init. */
150 asm ("mov %%gs, %w0" : "=q" (sel
) : "0" (0));
151 if (sel
== state
->ds
) /* _hurd_tls_init was never called. */
154 tcbhead_t
*const tcb
= THREAD_SELF
;
155 HURD_TLS_DESC_DECL (desc
, tcb
);
158 if (__builtin_expect (sel
, 0x50) & 4) /* LDT selector */
159 err
= __i386_set_ldt (child
, sel
, &desc
, 1);
161 err
= __i386_set_gdt (child
, &sel
, desc
);
167 #endif /* !__ASSEMBLER__ */
169 #endif /* i386/tls.h */