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  */
  77 #define TIF_SYSCALL_TRACE       0       /* syscall trace active */
  78 #define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
  79 #define TIF_SIGPENDING          2       /* signal pending */
  80 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
  81 #define TIF_SINGLESTEP          4       /* reenable singlestep on user return*/
  82 #define TIF_SYSCALL_EMU         6       /* syscall emulation active */
  83 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
  84 #define TIF_SECCOMP             8       /* secure computing */
  85 #define TIF_USER_RETURN_NOTIFY  11      /* notify kernel of userspace return */
  86 #define TIF_UPROBE              12      /* breakpointed or singlestepping */
  87 #define TIF_PATCH_PENDING       13      /* pending live patching update */
  88 #define TIF_NOCPUID             15      /* CPUID is not accessible in userland */
  89 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
  90 #define TIF_IA32                17      /* IA32 compatibility process */
  91 #define TIF_NOHZ                19      /* in adaptive nohz mode */
  92 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
  93 #define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
  94 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
  95 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
  96 #define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
  97 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
  98 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
  99 #define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
 100 #define TIF_X32                 30      /* 32-bit native x86-64 binary */
 101
 102 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 103 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 104 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 105 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 106 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 107 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 108 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 109 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 110 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 111 #define _TIF_UPROBE             (1 << TIF_UPROBE)
 112 #define _TIF_PATCH_PENDING      (1 << TIF_PATCH_PENDING)
 113 #define _TIF_NOCPUID            (1 << TIF_NOCPUID)
 114 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 115 #define _TIF_IA32               (1 << TIF_IA32)
 116 #define _TIF_NOHZ               (1 << TIF_NOHZ)
 117 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 118 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 119 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
 120 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 121 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 122 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 123 #define _TIF_ADDR32             (1 << TIF_ADDR32)
 124 #define _TIF_X32                (1 << TIF_X32)
 125
 126 /*
 127  * work to do in syscall_trace_enter().  Also includes TIF_NOHZ for
 128  * enter_from_user_mode()
 129  */
 130 #define _TIF_WORK_SYSCALL_ENTRY \
 131         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
 132          _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |       \
 133          _TIF_NOHZ)
 134
 135 /* work to do on any return to user space */
 136 #define _TIF_ALLWORK_MASK                                               \
 137         (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING |    \
 138          _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU |       \
 139          _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE |   \
 140          _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT)
 141
 142 /* flags to check in __switch_to() */
 143 #define _TIF_WORK_CTXSW                                                 \
 144         (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP)
 145
 146 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 147 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
 148
 149 #define STACK_WARN              (THREAD_SIZE/8)
 150
 151 /*
 152  * macros/functions for gaining access to the thread information structure
 153  *
 154  * preempt_count needs to be 1 initially, until the scheduler is functional.
 155  */
 156 #ifndef __ASSEMBLY__
 157
 158 static inline unsigned long current_stack_pointer(void)
 159 {
 160         unsigned long sp;
 161 #ifdef CONFIG_X86_64
 162         asm("mov %%rsp,%0" : "=g" (sp));
 163 #else
 164         asm("mov %%esp,%0" : "=g" (sp));
 165 #endif
 166         return sp;
 167 }
 168
 169 /*
 170  * Walks up the stack frames to make sure that the specified object is
 171  * entirely contained by a single stack frame.
 172  *
 173  * Returns:
 174  *      GOOD_FRAME      if within a frame
 175  *      BAD_STACK       if placed across a frame boundary (or outside stack)
 176  *      NOT_STACK       unable to determine (no frame pointers, etc)
 177  */
 178 static inline int arch_within_stack_frames(const void * const stack,
 179                                            const void * const stackend,
 180                                            const void *obj, unsigned long len)
 181 {
 182 #if defined(CONFIG_FRAME_POINTER)
 183         const void *frame = NULL;
 184         const void *oldframe;
 185
 186         oldframe = __builtin_frame_address(1);
 187         if (oldframe)
 188                 frame = __builtin_frame_address(2);
 189         /*
 190          * low ----------------------------------------------> high
 191          * [saved bp][saved ip][args][local vars][saved bp][saved ip]
 192          *                     ^----------------^
 193          *               allow copies only within here
 194          */
 195         while (stack <= frame && frame < stackend) {
 196                 /*
 197                  * If obj + len extends past the last frame, this
 198                  * check won't pass and the next frame will be 0,
 199                  * causing us to bail out and correctly report
 200                  * the copy as invalid.
 201                  */
 202                 if (obj + len <= frame)
 203                         return obj >= oldframe + 2 * sizeof(void *) ?
 204                                 GOOD_FRAME : BAD_STACK;
 205                 oldframe = frame;
 206                 frame = *(const void * const *)frame;
 207         }
 208         return BAD_STACK;
 209 #else
 210         return NOT_STACK;
 211 #endif
 212 }
 213
 214 #else /* !__ASSEMBLY__ */
 215
 216 #ifdef CONFIG_X86_64
 217 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
 218 #endif
 219
 220 #endif
 221
 222 #ifdef CONFIG_COMPAT
 223 #define TS_I386_REGS_POKED      0x0004  /* regs poked by 32-bit ptracer */
 224 #endif
 225 #ifndef __ASSEMBLY__
 226
 227 #ifdef CONFIG_X86_32
 228 #define in_ia32_syscall() true
 229 #else
 230 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
 231                            current->thread.status & TS_COMPAT)
 232 #endif
 233
 234 /*
 235  * Force syscall return via IRET by making it look as if there was
 236  * some work pending. IRET is our most capable (but slowest) syscall
 237  * return path, which is able to restore modified SS, CS and certain
 238  * EFLAGS values that other (fast) syscall return instructions
 239  * are not able to restore properly.
 240  */
 241 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
 242
 243 extern void arch_task_cache_init(void);
 244 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 245 extern void arch_release_task_struct(struct task_struct *tsk);
 246 extern void arch_setup_new_exec(void);
 247 #define arch_setup_new_exec arch_setup_new_exec
 248 #endif  /* !__ASSEMBLY__ */
 249
 250 #endif /* _ASM_X86_THREAD_INFO_H */