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         u32                     status;         /* thread synchronous flags */
  59 };
  60
  61 #define INIT_THREAD_INFO(tsk)                   \
  62 {                                               \
  63         .flags          = 0,                    \
  64 }
  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_SSBD                5       /* Speculative store bypass disable */
  83 #define TIF_SYSCALL_EMU         6       /* syscall emulation active */
  84 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
  85 #define TIF_SECCOMP             8       /* secure computing */
  86 #define TIF_SPEC_IB             9       /* Indirect branch speculation mitigation */
  87 #define TIF_SPEC_FORCE_UPDATE   10      /* Force speculation MSR update in context switch */
  88 #define TIF_USER_RETURN_NOTIFY  11      /* notify kernel of userspace return */
  89 #define TIF_UPROBE              12      /* breakpointed or singlestepping */
  90 #define TIF_PATCH_PENDING       13      /* pending live patching update */
  91 #define TIF_NOCPUID             15      /* CPUID is not accessible in userland */
  92 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
  93 #define TIF_IA32                17      /* IA32 compatibility process */
  94 #define TIF_NOHZ                19      /* in adaptive nohz mode */
  95 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
  96 #define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
  97 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
  98 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
  99 #define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
 100 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
 101 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
 102 #define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
 103 #define TIF_X32                 30      /* 32-bit native x86-64 binary */
 104 #define TIF_FSCHECK             31      /* Check FS is USER_DS on return */
 105
 106 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 107 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 108 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 109 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 110 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 111 #define _TIF_SSBD               (1 << TIF_SSBD)
 112 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
 113 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 114 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 115 #define _TIF_SPEC_IB            (1 << TIF_SPEC_IB)
 116 #define _TIF_SPEC_FORCE_UPDATE  (1 << TIF_SPEC_FORCE_UPDATE)
 117 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
 118 #define _TIF_UPROBE             (1 << TIF_UPROBE)
 119 #define _TIF_PATCH_PENDING      (1 << TIF_PATCH_PENDING)
 120 #define _TIF_NOCPUID            (1 << TIF_NOCPUID)
 121 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 122 #define _TIF_IA32               (1 << TIF_IA32)
 123 #define _TIF_NOHZ               (1 << TIF_NOHZ)
 124 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
 125 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 126 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
 127 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
 128 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
 129 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
 130 #define _TIF_ADDR32             (1 << TIF_ADDR32)
 131 #define _TIF_X32                (1 << TIF_X32)
 132 #define _TIF_FSCHECK            (1 << TIF_FSCHECK)
 133
 134 /*
 135  * work to do in syscall_trace_enter().  Also includes TIF_NOHZ for
 136  * enter_from_user_mode()
 137  */
 138 #define _TIF_WORK_SYSCALL_ENTRY \
 139         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
 140          _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |       \
 141          _TIF_NOHZ)
 142
 143 /* work to do on any return to user space */
 144 #define _TIF_ALLWORK_MASK                                               \
 145         (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING |    \
 146          _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU |       \
 147          _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE |   \
 148          _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT |     \
 149          _TIF_FSCHECK)
 150
 151 /* flags to check in __switch_to() */
 152 #define _TIF_WORK_CTXSW_BASE                                            \
 153         (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP|         \
 154          _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
 155
 156 /*
 157  * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
 158  */
 159 #ifdef CONFIG_SMP
 160 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
 161 #else
 162 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE)
 163 #endif
 164
 165 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
 166 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
 167
 168 #define STACK_WARN              (THREAD_SIZE/8)
 169
 170 /*
 171  * macros/functions for gaining access to the thread information structure
 172  *
 173  * preempt_count needs to be 1 initially, until the scheduler is functional.
 174  */
 175 #ifndef __ASSEMBLY__
 176
 177 /*
 178  * Walks up the stack frames to make sure that the specified object is
 179  * entirely contained by a single stack frame.
 180  *
 181  * Returns:
 182  *      GOOD_FRAME      if within a frame
 183  *      BAD_STACK       if placed across a frame boundary (or outside stack)
 184  *      NOT_STACK       unable to determine (no frame pointers, etc)
 185  */
 186 static inline int arch_within_stack_frames(const void * const stack,
 187                                            const void * const stackend,
 188                                            const void *obj, unsigned long len)
 189 {
 190 #if defined(CONFIG_FRAME_POINTER)
 191         const void *frame = NULL;
 192         const void *oldframe;
 193
 194         oldframe = __builtin_frame_address(1);
 195         if (oldframe)
 196                 frame = __builtin_frame_address(2);
 197         /*
 198          * low ----------------------------------------------> high
 199          * [saved bp][saved ip][args][local vars][saved bp][saved ip]
 200          *                     ^----------------^
 201          *               allow copies only within here
 202          */
 203         while (stack <= frame && frame < stackend) {
 204                 /*
 205                  * If obj + len extends past the last frame, this
 206                  * check won't pass and the next frame will be 0,
 207                  * causing us to bail out and correctly report
 208                  * the copy as invalid.
 209                  */
 210                 if (obj + len <= frame)
 211                         return obj >= oldframe + 2 * sizeof(void *) ?
 212                                 GOOD_FRAME : BAD_STACK;
 213                 oldframe = frame;
 214                 frame = *(const void * const *)frame;
 215         }
 216         return BAD_STACK;
 217 #else
 218         return NOT_STACK;
 219 #endif
 220 }
 221
 222 #else /* !__ASSEMBLY__ */
 223
 224 #ifdef CONFIG_X86_64
 225 # define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
 226 #endif
 227
 228 #endif
 229
 230 #ifdef CONFIG_COMPAT
 231 #define TS_I386_REGS_POKED      0x0004  /* regs poked by 32-bit ptracer */
 232 #endif
 233 #ifndef __ASSEMBLY__
 234
 235 #ifdef CONFIG_X86_32
 236 #define in_ia32_syscall() true
 237 #else
 238 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
 239                            current_thread_info()->status & TS_COMPAT)
 240 #endif
 241
 242 /*
 243  * Force syscall return via IRET by making it look as if there was
 244  * some work pending. IRET is our most capable (but slowest) syscall
 245  * return path, which is able to restore modified SS, CS and certain
 246  * EFLAGS values that other (fast) syscall return instructions
 247  * are not able to restore properly.
 248  */
 249 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
 250
 251 extern void arch_task_cache_init(void);
 252 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 253 extern void arch_release_task_struct(struct task_struct *tsk);
 254 extern void arch_setup_new_exec(void);
 255 #define arch_setup_new_exec arch_setup_new_exec
 256 #endif  /* !__ASSEMBLY__ */
 257
 258 #endif /* _ASM_X86_THREAD_INFO_H */