arch/x86/include/asm/thread_info.h

   1 /* thread_info.h: 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_X86_THREAD_INFO_H
   8 #define _ASM_X86_THREAD_INFO_H
   9
  10 #include <linux/compiler.h>
  11 #include <asm/page.h>
  12 #include <asm/percpu.h>
  13 #include <asm/types.h>
  14
  15 /*
  16  * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
  17  * reserve at the top of the kernel stack.  We do it because of a nasty
  18  * 32-bit corner case.  On x86_32, the hardware stack frame is
  19  * variable-length.  Except for vm86 mode, struct pt_regs assumes a
  20  * maximum-length frame.  If we enter from CPL 0, the top 8 bytes of
  21  * pt_regs don't actually exist.  Ordinarily this doesn't matter, but it
  22  * does in at least one case:
  23  *
  24  * If we take an NMI early enough in SYSENTER, then we can end up with
  25  * pt_regs that extends above sp0.  On the way out, in the espfix code,
  26  * we can read the saved SS value, but that value will be above sp0.
  27  * Without this offset, that can result in a page fault.  (We are
  28  * careful that, in this case, the value we read doesn't matter.)
  29  *
  30  * In vm86 mode, the hardware frame is much longer still, but we neither
  31  * access the extra members from NMI context, nor do we write such a
  32  * frame at sp0 at all.
  33  *
  34  * x86_64 has a fixed-length stack frame.
  35  */
  36 #ifdef CONFIG_X86_32
  37 # define TOP_OF_KERNEL_STACK_PADDING 8
  38 #else
  39 # define TOP_OF_KERNEL_STACK_PADDING 0
  40 #endif
  41
  42 /*
  43  * low level task data that entry.S needs immediate access to
  44  * - this struct should fit entirely inside of one cache line
  45  * - this struct shares the supervisor stack pages
  46  */
  47 #ifndef __ASSEMBLY__
  48 struct task_struct;
  49 struct exec_domain;
  50 #include <asm/processor.h>
  51 #include <linux/atomic.h>
  52
  53 struct thread_info {
  54         struct task_struct      *task;          /* main task structure */
  55         struct exec_domain      *exec_domain;   /* execution domain */
  56         __u32                   flags;          /* low level flags */
  57         __u32                   status;         /* thread synchronous flags */
  58         __u32                   cpu;            /* current CPU */
  59         int                     saved_preempt_count;
  60         mm_segment_t            addr_limit;
  61         void __user             *sysenter_return;
  62         unsigned int            sig_on_uaccess_error:1;
  63         unsigned int            uaccess_err:1;  /* uaccess failed */
  64 };
  65
  66 #define INIT_THREAD_INFO(tsk)                   \
  67 {                                               \
  68         .task           = &tsk,                 \
  69         .exec_domain    = &default_exec_domain, \
  70         .flags          = 0,                    \
  71         .cpu            = 0,                    \
  72         .saved_preempt_count = INIT_PREEMPT_COUNT,      \
  73         .addr_limit     = KERNEL_DS,            \
  74 }
  75
  76 #define init_thread_info        (init_thread_union.thread_info)
  77 #define init_stack              (init_thread_union.stack)
  78
  79 #else /* !__ASSEMBLY__ */
  80
  81 #include <asm/asm-offsets.h>
  82
  83 #endif
  84
  85 /*
  86  * thread information flags
  87  * - these are process state flags that various assembly files
  88  *   may need to access
  89  * - pending work-to-be-done flags are in LSW
  90  * - other flags in MSW
  91  * Warning: layout of LSW is hardcoded in entry.S
  92  */
  93 #define TIF_SYSCALL_TRACE       0       /* syscall trace active */
  94 #define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
  95 #define TIF_SIGPENDING          2       /* signal pending */
  96 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
  97 #define TIF_SINGLESTEP          4       /* reenable singlestep on user return*/
  98 #define TIF_SYSCALL_EMU         6       /* syscall emulation active */
  99 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 100 #define TIF_SECCOMP             8       /* secure computing */
 101 #define TIF_USER_RETURN_NOTIFY  11      /* notify kernel of userspace return */
 102 #define TIF_UPROBE              12      /* breakpointed or singlestepping */
 103 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
 104 #define TIF_IA32                17      /* IA32 compatibility process */
 105 #define TIF_FORK                18      /* ret_from_fork */
 106 #define TIF_NOHZ                19      /* in adaptive nohz mode */
 107 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
 108 #define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
 109 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
 110 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
 111 #define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
 112 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
 113 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
 114 #define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
 115 #define TIF_X32                 30      /* 32-bit native x86-64 binary */
 116
 117 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 118 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 119 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 120 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 121 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 122 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 123 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 124 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 125 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 126 #define _TIF_UPROBE             (1 << TIF_UPROBE)
 127 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 128 #define _TIF_IA32               (1 << TIF_IA32)
 129 #define _TIF_FORK               (1 << TIF_FORK)
 130 #define _TIF_NOHZ               (1 << TIF_NOHZ)
 131 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 132 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 133 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
 134 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 135 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 136 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 137 #define _TIF_ADDR32             (1 << TIF_ADDR32)
 138 #define _TIF_X32                (1 << TIF_X32)
 139
 140 /* work to do in syscall_trace_enter() */
 141 #define _TIF_WORK_SYSCALL_ENTRY \
 142         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
 143          _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT |     \
 144          _TIF_NOHZ)
 145
 146 /* work to do in syscall_trace_leave() */
 147 #define _TIF_WORK_SYSCALL_EXIT  \
 148         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP |    \
 149          _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)
 150
 151 /* work to do on interrupt/exception return */
 152 #define _TIF_WORK_MASK                                                  \
 153         (0x0000FFFF &                                                   \
 154          ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|                       \
 155            _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
 156
 157 /* work to do on any return to user space */
 158 #define _TIF_ALLWORK_MASK                                               \
 159         ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |       \
 160         _TIF_NOHZ)
 161
 162 /* Only used for 64 bit */
 163 #define _TIF_DO_NOTIFY_MASK                                             \
 164         (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME |                         \
 165          _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE)
 166
 167 /* flags to check in __switch_to() */
 168 #define _TIF_WORK_CTXSW                                                 \
 169         (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
 170
 171 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 172 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
 173
 174 #define STACK_WARN              (THREAD_SIZE/8)
 175
 176 /*
 177  * macros/functions for gaining access to the thread information structure
 178  *
 179  * preempt_count needs to be 1 initially, until the scheduler is functional.
 180  */
 181 #ifndef __ASSEMBLY__
 182
 183 DECLARE_PER_CPU(unsigned long, kernel_stack);
 184
 185 static inline struct thread_info *current_thread_info(void)
 186 {
 187         return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
 188 }
 189
 190 static inline unsigned long current_stack_pointer(void)
 191 {
 192         unsigned long sp;
 193 #ifdef CONFIG_X86_64
 194         asm("mov %%rsp,%0" : "=g" (sp));
 195 #else
 196         asm("mov %%esp,%0" : "=g" (sp));
 197 #endif
 198         return sp;
 199 }
 200
 201 #else /* !__ASSEMBLY__ */
 202
 203 /* Load thread_info address into "reg" */
 204 #define GET_THREAD_INFO(reg) \
 205         _ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \
 206         _ASM_SUB $(THREAD_SIZE),reg ;
 207
 208 /*
 209  * ASM operand which evaluates to thread_info address
 210  * if it is known that "reg" is exactly "off" bytes below stack top.
 211  * Example (fetch thread_info->fieldname):
 212  *  mov TI_fieldname+THREAD_INFO(reg, off),%eax
 213  */
 214 #define THREAD_INFO(reg, off) ((off)-THREAD_SIZE)(reg)
 215
 216 #endif
 217
 218 /*
 219  * Thread-synchronous status.
 220  *
 221  * This is different from the flags in that nobody else
 222  * ever touches our thread-synchronous status, so we don't
 223  * have to worry about atomic accesses.
 224  */
 225 #define TS_COMPAT               0x0002  /* 32bit syscall active (64BIT)*/
 226 #define TS_RESTORE_SIGMASK      0x0008  /* restore signal mask in do_signal() */
 227
 228 #ifndef __ASSEMBLY__
 229 #define HAVE_SET_RESTORE_SIGMASK        1
 230 static inline void set_restore_sigmask(void)
 231 {
 232         struct thread_info *ti = current_thread_info();
 233         ti->status |= TS_RESTORE_SIGMASK;
 234         WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
 235 }
 236 static inline void clear_restore_sigmask(void)
 237 {
 238         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 239 }
 240 static inline bool test_restore_sigmask(void)
 241 {
 242         return current_thread_info()->status & TS_RESTORE_SIGMASK;
 243 }
 244 static inline bool test_and_clear_restore_sigmask(void)
 245 {
 246         struct thread_info *ti = current_thread_info();
 247         if (!(ti->status & TS_RESTORE_SIGMASK))
 248                 return false;
 249         ti->status &= ~TS_RESTORE_SIGMASK;
 250         return true;
 251 }
 252
 253 static inline bool is_ia32_task(void)
 254 {
 255 #ifdef CONFIG_X86_32
 256         return true;
 257 #endif
 258 #ifdef CONFIG_IA32_EMULATION
 259         if (current_thread_info()->status & TS_COMPAT)
 260                 return true;
 261 #endif
 262         return false;
 263 }
 264
 265 /*
 266  * Force syscall return via IRET by making it look as if there was
 267  * some work pending. IRET is our most capable (but slowest) syscall
 268  * return path, which is able to restore modified SS, CS and certain
 269  * EFLAGS values that other (fast) syscall return instructions
 270  * are not able to restore properly.
 271  */
 272 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
 273
 274 #endif  /* !__ASSEMBLY__ */
 275
 276 #ifndef __ASSEMBLY__
 277 extern void arch_task_cache_init(void);
 278 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 279 extern void arch_release_task_struct(struct task_struct *tsk);
 280 #endif
 281 #endif /* _ASM_X86_THREAD_INFO_H */