1 /* thread_info.h: i386 low-level thread information
2 *
3 * Copyright (C) 2002 David Howells (dhowells@redhat.com)
4 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
5 */
6
7 #ifndef _ASM_THREAD_INFO_H
8 #define _ASM_THREAD_INFO_H
9
10 #ifdef __KERNEL__
11
12 #include <linux/compiler.h>
13 #include <asm/page.h>
14
15 #ifndef __ASSEMBLY__
16 #include <asm/processor.h>
17 #endif
18
19 /*
20 * low level task data that entry.S needs immediate access to
21 * - this struct should fit entirely inside of one cache line
22 * - this struct shares the supervisor stack pages
23 * - if the contents of this structure are changed, the assembly constants must also be changed
24 */
25 #ifndef __ASSEMBLY__
26
27 struct thread_info {
28 struct task_struct *task; /* main task structure */
29 struct exec_domain *exec_domain; /* execution domain */
30 unsigned long flags; /* low level flags */
31 unsigned long status; /* thread-synchronous flags */
32 __u32 cpu; /* current CPU */
33 int preempt_count; /* 0 => preemptable, <0 => BUG */
34
35
36 mm_segment_t addr_limit; /* thread address space:
37 0-0xBFFFFFFF for user-thead
38 0-0xFFFFFFFF for kernel-thread
39 */
40 void *sysenter_return;
41 struct restart_block restart_block;
42
43 unsigned long previous_esp; /* ESP of the previous stack in case
44 of nested (IRQ) stacks
45 */
46 __u8 supervisor_stack[0];
47 };
48
49 #else /* !__ASSEMBLY__ */
50
51 #include <asm/asm-offsets.h>
52
53 #endif
54
55 #define PREEMPT_ACTIVE 0x10000000
56 #ifdef CONFIG_4KSTACKS
57 #define THREAD_SIZE (4096)
58 #else
59 #define THREAD_SIZE (8192)
60 #endif
61
62 #define STACK_WARN (THREAD_SIZE/8)
63 /*
64 * macros/functions for gaining access to the thread information structure
65 *
66 * preempt_count needs to be 1 initially, until the scheduler is functional.
67 */
68 #ifndef __ASSEMBLY__
69
70 #define INIT_THREAD_INFO(tsk) \
71 { \
72 .task = &tsk, \
73 .exec_domain = &default_exec_domain, \
74 .flags = 0, \
75 .cpu = 0, \
76 .preempt_count = 1, \
77 .addr_limit = KERNEL_DS, \
78 .restart_block = { \
79 .fn = do_no_restart_syscall, \
80 }, \
81 }
82
83 #define init_thread_info (init_thread_union.thread_info)
84 #define init_stack (init_thread_union.stack)
85
86
87 /* how to get the current stack pointer from C */
88 register unsigned long current_stack_pointer asm("esp") __attribute_used__;
89
90 /* how to get the thread information struct from C */
current_thread_info(void)91 static inline struct thread_info *current_thread_info(void)
92 {
93 return (struct thread_info *)(current_stack_pointer & ~(THREAD_SIZE - 1));
94 }
95
96 /* thread information allocation */
97 #ifdef CONFIG_DEBUG_STACK_USAGE
98 #define alloc_thread_info(tsk) ((struct thread_info *) \
99 __get_free_pages(GFP_KERNEL| __GFP_ZERO, get_order(THREAD_SIZE)))
100 #else
101 #define alloc_thread_info(tsk) ((struct thread_info *) \
102 __get_free_pages(GFP_KERNEL, get_order(THREAD_SIZE)))
103 #endif
104
105 #define free_thread_info(info) free_pages((unsigned long)(info), get_order(THREAD_SIZE))
106
107 #else /* !__ASSEMBLY__ */
108
109 /* how to get the thread information struct from ASM */
110 #define GET_THREAD_INFO(reg) \
111 movl $-THREAD_SIZE, reg; \
112 andl %esp, reg
113
114 /* use this one if reg already contains %esp */
115 #define GET_THREAD_INFO_WITH_ESP(reg) \
116 andl $-THREAD_SIZE, reg
117
118 #endif
119
120 /*
121 * thread information flags
122 * - these are process state flags that various assembly files may need to access
123 * - pending work-to-be-done flags are in LSW
124 * - other flags in MSW
125 */
126 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
127 #define TIF_SIGPENDING 1 /* signal pending */
128 #define TIF_NEED_RESCHED 2 /* rescheduling necessary */
129 #define TIF_SINGLESTEP 3 /* restore singlestep on return to user mode */
130 #define TIF_IRET 4 /* return with iret */
131 #define TIF_SYSCALL_EMU 5 /* syscall emulation active */
132 #define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */
133 #define TIF_SECCOMP 7 /* secure computing */
134 #define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal() */
135 #define TIF_MEMDIE 16
136 #define TIF_DEBUG 17 /* uses debug registers */
137 #define TIF_IO_BITMAP 18 /* uses I/O bitmap */
138 #define TIF_FREEZE 19 /* is freezing for suspend */
139 #define TIF_NOTSC 20 /* TSC is not accessible in userland */
140
141 #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
142 #define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
143 #define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
144 #define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
145 #define _TIF_IRET (1<<TIF_IRET)
146 #define _TIF_SYSCALL_EMU (1<<TIF_SYSCALL_EMU)
147 #define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
148 #define _TIF_SECCOMP (1<<TIF_SECCOMP)
149 #define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
150 #define _TIF_DEBUG (1<<TIF_DEBUG)
151 #define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
152 #define _TIF_FREEZE (1<<TIF_FREEZE)
153 #define _TIF_NOTSC (1<<TIF_NOTSC)
154
155 /* work to do on interrupt/exception return */
156 #define _TIF_WORK_MASK \
157 (0x0000FFFF & ~(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
158 _TIF_SECCOMP | _TIF_SYSCALL_EMU))
159 /* work to do on any return to u-space */
160 #define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
161
162 /* flags to check in __switch_to() */
163 #define _TIF_WORK_CTXSW_NEXT (_TIF_IO_BITMAP | _TIF_NOTSC | _TIF_DEBUG)
164 #define _TIF_WORK_CTXSW_PREV (_TIF_IO_BITMAP | _TIF_NOTSC)
165
166 /*
167 * Thread-synchronous status.
168 *
169 * This is different from the flags in that nobody else
170 * ever touches our thread-synchronous status, so we don't
171 * have to worry about atomic accesses.
172 */
173 #define TS_USEDFPU 0x0001 /* FPU was used by this task this quantum (SMP) */
174 #define TS_POLLING 0x0002 /* True if in idle loop and not sleeping */
175
176 #define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
177
178 #endif /* __KERNEL__ */
179
180 #endif /* _ASM_THREAD_INFO_H */
181