arch/x86/include/asm/thread_info.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* thread_info.h: low-level thread information
   3  *
   4  * Copyright (C) 2002  David Howells (dhowells@redhat.com)
   5  * - Incorporating suggestions made by Linus Torvalds and Dave Miller
   6  */
   7
   8 #ifndef _ASM_X86_THREAD_INFO_H
   9 #define _ASM_X86_THREAD_INFO_H
  10
  11 #include <linux/compiler.h>
  12 #include <asm/page.h>
  13 #include <asm/percpu.h>
  14 #include <asm/types.h>
  15
  16 /*
  17  * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
  18  * reserve at the top of the kernel stack.  We do it because of a nasty
  19  * 32-bit corner case.  On x86_32, the hardware stack frame is
  20  * variable-length.  Except for vm86 mode, struct pt_regs assumes a
  21  * maximum-length frame.  If we enter from CPL 0, the top 8 bytes of
  22  * pt_regs don't actually exist.  Ordinarily this doesn't matter, but it
  23  * does in at least one case:
  24  *
  25  * If we take an NMI early enough in SYSENTER, then we can end up with
  26  * pt_regs that extends above sp0.  On the way out, in the espfix code,
  27  * we can read the saved SS value, but that value will be above sp0.
  28  * Without this offset, that can result in a page fault.  (We are
  29  * careful that, in this case, the value we read doesn't matter.)
  30  *
  31  * In vm86 mode, the hardware frame is much longer still, so add 16
  32  * bytes to make room for the real-mode segments.
  33  *
  34  * x86_64 has a fixed-length stack frame.
  35  */
  36 #ifdef CONFIG_X86_32
  37 # ifdef CONFIG_VM86
  38 #  define TOP_OF_KERNEL_STACK_PADDING 16
  39 # else
  40 #  define TOP_OF_KERNEL_STACK_PADDING 8
  41 # endif
  42 #else
  43 # define TOP_OF_KERNEL_STACK_PADDING 0
  44 #endif
  45
  46 /*
  47  * low level task data that entry.S needs immediate access to
  48  * - this struct should fit entirely inside of one cache line
  49  * - this struct shares the supervisor stack pages
  50  */
  51 #ifndef __ASSEMBLY__
  52 struct task_struct;
  53 #include <asm/cpufeature.h>
  54 #include <linux/atomic.h>
  55
  56 struct thread_info {
  57         unsigned long           flags;          /* low level flags */
  58         unsigned long           syscall_work;   /* SYSCALL_WORK_ flags */
  59         u32                     status;         /* thread synchronous flags */
  60 };
  61
  62 #define INIT_THREAD_INFO(tsk)                   \
  63 {                                               \
  64         .flags          = 0,                    \
  65 }
  66
  67 #else /* !__ASSEMBLY__ */
  68
  69 #include <asm/asm-offsets.h>
  70
  71 #endif
  72
  73 /*
  74  * thread information flags
  75  * - these are process state flags that various assembly files
  76  *   may need to access
  77  */
  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_SSBD                5       /* Speculative store bypass disable */
  83 #define TIF_SPEC_IB             9       /* Indirect branch speculation mitigation */
  84 #define TIF_SPEC_FORCE_UPDATE   10      /* Force speculation MSR update in context switch */
  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_NEED_FPU_LOAD       14      /* load FPU on return to userspace */
  89 #define TIF_NOCPUID             15      /* CPUID is not accessible in userland */
  90 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
  91 #define TIF_NOTIFY_SIGNAL       17      /* signal notifications exist */
  92 #define TIF_SLD                 18      /* Restore split lock detection on context switch */
  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_ADDR32              29      /* 32-bit address space on 64 bits */
 100
 101 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 102 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 103 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 104 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 105 #define _TIF_SSBD               (1 << TIF_SSBD)
 106 #define _TIF_SPEC_IB            (1 << TIF_SPEC_IB)
 107 #define _TIF_SPEC_FORCE_UPDATE  (1 << TIF_SPEC_FORCE_UPDATE)
 108 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 109 #define _TIF_UPROBE             (1 << TIF_UPROBE)
 110 #define _TIF_PATCH_PENDING      (1 << TIF_PATCH_PENDING)
 111 #define _TIF_NEED_FPU_LOAD      (1 << TIF_NEED_FPU_LOAD)
 112 #define _TIF_NOCPUID            (1 << TIF_NOCPUID)
 113 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 114 #define _TIF_NOTIFY_SIGNAL      (1 << TIF_NOTIFY_SIGNAL)
 115 #define _TIF_SLD                (1 << TIF_SLD)
 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_ADDR32             (1 << TIF_ADDR32)
 122
 123 /* flags to check in __switch_to() */
 124 #define _TIF_WORK_CTXSW_BASE                                    \
 125         (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP |           \
 126          _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE | _TIF_SLD)
 127
 128 /*
 129  * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
 130  */
 131 #ifdef CONFIG_SMP
 132 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
 133 #else
 134 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE)
 135 #endif
 136
 137 #ifdef CONFIG_X86_IOPL_IOPERM
 138 # define _TIF_WORK_CTXSW_PREV   (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
 139                                  _TIF_IO_BITMAP)
 140 #else
 141 # define _TIF_WORK_CTXSW_PREV   (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
 142 #endif
 143
 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 /*
 156  * Walks up the stack frames to make sure that the specified object is
 157  * entirely contained by a single stack frame.
 158  *
 159  * Returns:
 160  *      GOOD_FRAME      if within a frame
 161  *      BAD_STACK       if placed across a frame boundary (or outside stack)
 162  *      NOT_STACK       unable to determine (no frame pointers, etc)
 163  */
 164 static inline int arch_within_stack_frames(const void * const stack,
 165                                            const void * const stackend,
 166                                            const void *obj, unsigned long len)
 167 {
 168 #if defined(CONFIG_FRAME_POINTER)
 169         const void *frame = NULL;
 170         const void *oldframe;
 171
 172         oldframe = __builtin_frame_address(1);
 173         if (oldframe)
 174                 frame = __builtin_frame_address(2);
 175         /*
 176          * low ----------------------------------------------> high
 177          * [saved bp][saved ip][args][local vars][saved bp][saved ip]
 178          *                     ^----------------^
 179          *               allow copies only within here
 180          */
 181         while (stack <= frame && frame < stackend) {
 182                 /*
 183                  * If obj + len extends past the last frame, this
 184                  * check won't pass and the next frame will be 0,
 185                  * causing us to bail out and correctly report
 186                  * the copy as invalid.
 187                  */
 188                 if (obj + len <= frame)
 189                         return obj >= oldframe + 2 * sizeof(void *) ?
 190                                 GOOD_FRAME : BAD_STACK;
 191                 oldframe = frame;
 192                 frame = *(const void * const *)frame;
 193         }
 194         return BAD_STACK;
 195 #else
 196         return NOT_STACK;
 197 #endif
 198 }
 199
 200 #else /* !__ASSEMBLY__ */
 201
 202 #ifdef CONFIG_X86_64
 203 # define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
 204 #endif
 205
 206 #endif
 207
 208 /*
 209  * Thread-synchronous status.
 210  *
 211  * This is different from the flags in that nobody else
 212  * ever touches our thread-synchronous status, so we don't
 213  * have to worry about atomic accesses.
 214  */
 215 #define TS_COMPAT               0x0002  /* 32bit syscall active (64BIT)*/
 216
 217 #ifndef __ASSEMBLY__
 218 #ifdef CONFIG_COMPAT
 219 #define TS_I386_REGS_POKED      0x0004  /* regs poked by 32-bit ptracer */
 220 #define TS_COMPAT_RESTART       0x0008
 221
 222 #define arch_set_restart_data   arch_set_restart_data
 223
 224 static inline void arch_set_restart_data(struct restart_block *restart)
 225 {
 226         struct thread_info *ti = current_thread_info();
 227         if (ti->status & TS_COMPAT)
 228                 ti->status |= TS_COMPAT_RESTART;
 229         else
 230                 ti->status &= ~TS_COMPAT_RESTART;
 231 }
 232 #endif
 233
 234 #ifdef CONFIG_X86_32
 235 #define in_ia32_syscall() true
 236 #else
 237 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
 238                            current_thread_info()->status & TS_COMPAT)
 239 #endif
 240
 241 extern void arch_task_cache_init(void);
 242 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 243 extern void arch_release_task_struct(struct task_struct *tsk);
 244 extern void arch_setup_new_exec(void);
 245 #define arch_setup_new_exec arch_setup_new_exec
 246 #endif  /* !__ASSEMBLY__ */
 247
 248 #endif /* _ASM_X86_THREAD_INFO_H */