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   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/config.h>
  13 #include <linux/compiler.h>
  14 #include <asm/page.h>
  15
  16 #ifndef __ASSEMBLY__
  17 #include <asm/processor.h>
  18 #endif
  19
  20 /*
  21  * low level task data that entry.S needs immediate access to
  22  * - this struct should fit entirely inside of one cache line
  23  * - this struct shares the supervisor stack pages
  24  * - if the contents of this structure are changed, the assembly constants must also be changed
  25  */
  26 #ifndef __ASSEMBLY__
  27
  28 struct thread_info {
  29         struct task_struct      *task;          /* main task structure */
  30         struct exec_domain      *exec_domain;   /* execution domain */
  31         unsigned long           flags;          /* low level flags */
  32         unsigned long           status;         /* thread-synchronous flags */
  33         __u32                   cpu;            /* current CPU */
  34         __s32                   preempt_count; /* 0 => preemptable, <0 => BUG */
  35
  36
  37         mm_segment_t            addr_limit;     /* thread address space:
  38                                                    0-0xBFFFFFFF for user-thead
  39                                                    0-0xFFFFFFFF for kernel-thread
  40                                                 */
  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 thread information struct from C */
  88 static inline struct thread_info *current_thread_info(void)
  89 {
  90         struct thread_info *ti;
  91         __asm__("andl %%esp,%0; ":"=r" (ti) : "0" (~(THREAD_SIZE - 1)));
  92         return ti;
  93 }
  94
  95 /* how to get the current stack pointer from C */
  96 register unsigned long current_stack_pointer asm("esp") __attribute_used__;
  97
  98 /* thread information allocation */
  99 #ifdef CONFIG_DEBUG_STACK_USAGE
 100 #define alloc_thread_info(tsk)                                  \
 101         ({                                                      \
 102                 struct thread_info *ret;                        \
 103                                                                 \
 104                 ret = kmalloc(THREAD_SIZE, GFP_KERNEL);         \
 105                 if (ret)                                        \
 106                         memset(ret, 0, THREAD_SIZE);            \
 107                 ret;                                            \
 108         })
 109 #else
 110 #define alloc_thread_info(tsk) kmalloc(THREAD_SIZE, GFP_KERNEL)
 111 #endif
 112
 113 #define free_thread_info(info)  kfree(info)
 114 #define get_thread_info(ti) get_task_struct((ti)->task)
 115 #define put_thread_info(ti) put_task_struct((ti)->task)
 116
 117 #else /* !__ASSEMBLY__ */
 118
 119 /* how to get the thread information struct from ASM */
 120 #define GET_THREAD_INFO(reg) \
 121         movl $-THREAD_SIZE, reg; \
 122         andl %esp, reg
 123
 124 /* use this one if reg already contains %esp */
 125 #define GET_THREAD_INFO_WITH_ESP(reg) \
 126         andl $-THREAD_SIZE, reg
 127
 128 #endif
 129
 130 /*
 131  * thread information flags
 132  * - these are process state flags that various assembly files may need to access
 133  * - pending work-to-be-done flags are in LSW
 134  * - other flags in MSW
 135  */
 136 #define TIF_SYSCALL_TRACE       0       /* syscall trace active */
 137 #define TIF_NOTIFY_RESUME       1       /* resumption notification requested */
 138 #define TIF_SIGPENDING          2       /* signal pending */
 139 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
 140 #define TIF_SINGLESTEP          4       /* restore singlestep on return to user mode */
 141 #define TIF_IRET                5       /* return with iret */
 142 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 143 #define TIF_SECCOMP             8       /* secure computing */
 144 #define TIF_POLLING_NRFLAG      16      /* true if poll_idle() is polling TIF_NEED_RESCHED */
 145 #define TIF_MEMDIE              17
 146
 147 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
 148 #define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
 149 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
 150 #define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
 151 #define _TIF_SINGLESTEP         (1<<TIF_SINGLESTEP)
 152 #define _TIF_IRET               (1<<TIF_IRET)
 153 #define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 154 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
 155 #define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 156
 157 /* work to do on interrupt/exception return */
 158 #define _TIF_WORK_MASK \
 159   (0x0000FFFF & ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP|_TIF_SECCOMP))
 160 /* work to do on any return to u-space */
 161 #define _TIF_ALLWORK_MASK       (0x0000FFFF & ~_TIF_SECCOMP)
 162
 163 /*
 164  * Thread-synchronous status.
 165  *
 166  * This is different from the flags in that nobody else
 167  * ever touches our thread-synchronous status, so we don't
 168  * have to worry about atomic accesses.
 169  */
 170 #define TS_USEDFPU              0x0001  /* FPU was used by this task this quantum (SMP) */
 171
 172 #endif /* __KERNEL__ */
 173
 174 #endif /* _ASM_THREAD_INFO_H */