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, so add 16
  31  * bytes to make room for the real-mode segments.
  32  *
  33  * x86_64 has a fixed-length stack frame.
  34  */
  35 #ifdef CONFIG_X86_32
  36 # ifdef CONFIG_VM86
  37 #  define TOP_OF_KERNEL_STACK_PADDING 16
  38 # else
  39 #  define TOP_OF_KERNEL_STACK_PADDING 8
  40 # endif
  41 #else
  42 # define TOP_OF_KERNEL_STACK_PADDING 0
  43 #endif
  44
  45 /*
  46  * low level task data that entry.S needs immediate access to
  47  * - this struct should fit entirely inside of one cache line
  48  * - this struct shares the supervisor stack pages
  49  */
  50 #ifndef __ASSEMBLY__
  51 struct task_struct;
  52 #include <asm/cpufeature.h>
  53 #include <linux/atomic.h>
  54
  55 struct thread_info {
  56         unsigned long           flags;          /* low level flags */
  57 };
  58
  59 #define INIT_THREAD_INFO(tsk)                   \
  60 {                                               \
  61         .flags          = 0,                    \
  62 }
  63
  64 #define init_stack              (init_thread_union.stack)
  65
  66 #else /* !__ASSEMBLY__ */
  67
  68 #include <asm/asm-offsets.h>
  69
  70 #endif
  71
  72 /*
  73  * thread information flags
  74  * - these are process state flags that various assembly files
  75  *   may need to access
  76  * - pending work-to-be-done flags are in LSW
  77  * - other flags in MSW
  78  * Warning: layout of LSW is hardcoded in entry.S
  79  */
  80 #define TIF_SYSCALL_TRACE       0       /* syscall trace active */
  81 #define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
  82 #define TIF_SIGPENDING          2       /* signal pending */
  83 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
  84 #define TIF_SINGLESTEP          4       /* reenable singlestep on user return*/
  85 #define TIF_SYSCALL_EMU         6       /* syscall emulation active */
  86 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
  87 #define TIF_SECCOMP             8       /* secure computing */
  88 #define TIF_USER_RETURN_NOTIFY  11      /* notify kernel of userspace return */
  89 #define TIF_UPROBE              12      /* breakpointed or singlestepping */
  90 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
  91 #define TIF_IA32                17      /* IA32 compatibility process */
  92 #define TIF_NOHZ                19      /* in adaptive nohz mode */
  93 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
  94 #define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
  95 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
  96 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
  97 #define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
  98 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
  99 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
 100 #define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
 101 #define TIF_X32                 30      /* 32-bit native x86-64 binary */
 102
 103 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 104 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 105 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 106 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 107 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 108 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 109 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 110 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 111 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 112 #define _TIF_UPROBE             (1 << TIF_UPROBE)
 113 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 114 #define _TIF_IA32               (1 << TIF_IA32)
 115 #define _TIF_NOHZ               (1 << TIF_NOHZ)
 116 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 117 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 118 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
 119 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 120 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 121 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 122 #define _TIF_ADDR32             (1 << TIF_ADDR32)
 123 #define _TIF_X32                (1 << TIF_X32)
 124
 125 /*
 126  * work to do in syscall_trace_enter().  Also includes TIF_NOHZ for
 127  * enter_from_user_mode()
 128  */
 129 #define _TIF_WORK_SYSCALL_ENTRY \
 130         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
 131          _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |       \
 132          _TIF_NOHZ)
 133
 134 /* work to do on any return to user space */
 135 #define _TIF_ALLWORK_MASK                                               \
 136         ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |       \
 137         _TIF_NOHZ)
 138
 139 /* flags to check in __switch_to() */
 140 #define _TIF_WORK_CTXSW                                                 \
 141         (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
 142
 143 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 144 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
 145
 146 #define STACK_WARN              (THREAD_SIZE/8)
 147
 148 /*
 149  * macros/functions for gaining access to the thread information structure
 150  *
 151  * preempt_count needs to be 1 initially, until the scheduler is functional.
 152  */
 153 #ifndef __ASSEMBLY__
 154
 155 static inline unsigned long current_stack_pointer(void)
 156 {
 157         unsigned long sp;
 158 #ifdef CONFIG_X86_64
 159         asm("mov %%rsp,%0" : "=g" (sp));
 160 #else
 161         asm("mov %%esp,%0" : "=g" (sp));
 162 #endif
 163         return sp;
 164 }
 165
 166 /*
 167  * Walks up the stack frames to make sure that the specified object is
 168  * entirely contained by a single stack frame.
 169  *
 170  * Returns:
 171  *               1 if within a frame
 172  *              -1 if placed across a frame boundary (or outside stack)
 173  *               0 unable to determine (no frame pointers, etc)
 174  */
 175 static inline int arch_within_stack_frames(const void * const stack,
 176                                            const void * const stackend,
 177                                            const void *obj, unsigned long len)
 178 {
 179 #if defined(CONFIG_FRAME_POINTER)
 180         const void *frame = NULL;
 181         const void *oldframe;
 182
 183         oldframe = __builtin_frame_address(1);
 184         if (oldframe)
 185                 frame = __builtin_frame_address(2);
 186         /*
 187          * low ----------------------------------------------> high
 188          * [saved bp][saved ip][args][local vars][saved bp][saved ip]
 189          *                     ^----------------^
 190          *               allow copies only within here
 191          */
 192         while (stack <= frame && frame < stackend) {
 193                 /*
 194                  * If obj + len extends past the last frame, this
 195                  * check won't pass and the next frame will be 0,
 196                  * causing us to bail out and correctly report
 197                  * the copy as invalid.
 198                  */
 199                 if (obj + len <= frame)
 200                         return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
 201                 oldframe = frame;
 202                 frame = *(const void * const *)frame;
 203         }
 204         return -1;
 205 #else
 206         return 0;
 207 #endif
 208 }
 209
 210 #else /* !__ASSEMBLY__ */
 211
 212 #ifdef CONFIG_X86_64
 213 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
 214 #endif
 215
 216 #endif
 217
 218 #ifdef CONFIG_COMPAT
 219 #define TS_I386_REGS_POKED      0x0004  /* regs poked by 32-bit ptracer */
 220 #endif
 221 #ifndef __ASSEMBLY__
 222
 223 #ifdef CONFIG_X86_32
 224 #define in_ia32_syscall() true
 225 #else
 226 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
 227                            current->thread.status & TS_COMPAT)
 228 #endif
 229
 230 /*
 231  * Force syscall return via IRET by making it look as if there was
 232  * some work pending. IRET is our most capable (but slowest) syscall
 233  * return path, which is able to restore modified SS, CS and certain
 234  * EFLAGS values that other (fast) syscall return instructions
 235  * are not able to restore properly.
 236  */
 237 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
 238
 239 extern void arch_task_cache_init(void);
 240 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 241 extern void arch_release_task_struct(struct task_struct *tsk);
 242 #endif  /* !__ASSEMBLY__ */
 243
 244 #endif /* _ASM_X86_THREAD_INFO_H */