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Linux/arch/x86/include/asm/thread_info.h

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  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_NEED_FPU_LOAD       14      /* load FPU on return to userspace */
 92 #define TIF_NOCPUID             15      /* CPUID is not accessible in userland */
 93 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
 94 #define TIF_IA32                17      /* IA32 compatibility process */
 95 #define TIF_NOHZ                19      /* in adaptive nohz mode */
 96 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
 97 #define TIF_POLLING_NRFLAG      21      /* idle is polling for TIF_NEED_RESCHED */
 98 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
 99 #define TIF_FORCED_TF           24      /* true if TF in eflags artificially */
100 #define TIF_BLOCKSTEP           25      /* set when we want DEBUGCTLMSR_BTF */
101 #define TIF_LAZY_MMU_UPDATES    27      /* task is updating the mmu lazily */
102 #define TIF_SYSCALL_TRACEPOINT  28      /* syscall tracepoint instrumentation */
103 #define TIF_ADDR32              29      /* 32-bit address space on 64 bits */
104 #define TIF_X32                 30      /* 32-bit native x86-64 binary */
105 #define TIF_FSCHECK             31      /* Check FS is USER_DS on return */
106 
107 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
108 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
109 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
110 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
111 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
112 #define _TIF_SSBD               (1 << TIF_SSBD)
113 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
114 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
115 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
116 #define _TIF_SPEC_IB            (1 << TIF_SPEC_IB)
117 #define _TIF_SPEC_FORCE_UPDATE  (1 << TIF_SPEC_FORCE_UPDATE)
118 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
119 #define _TIF_UPROBE             (1 << TIF_UPROBE)
120 #define _TIF_PATCH_PENDING      (1 << TIF_PATCH_PENDING)
121 #define _TIF_NEED_FPU_LOAD      (1 << TIF_NEED_FPU_LOAD)
122 #define _TIF_NOCPUID            (1 << TIF_NOCPUID)
123 #define _TIF_NOTSC              (1 << TIF_NOTSC)
124 #define _TIF_IA32               (1 << TIF_IA32)
125 #define _TIF_NOHZ               (1 << TIF_NOHZ)
126 #define _TIF_POLLING_NRFLAG     (1 << TIF_POLLING_NRFLAG)
127 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
128 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
129 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
130 #define _TIF_LAZY_MMU_UPDATES   (1 << TIF_LAZY_MMU_UPDATES)
131 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
132 #define _TIF_ADDR32             (1 << TIF_ADDR32)
133 #define _TIF_X32                (1 << TIF_X32)
134 #define _TIF_FSCHECK            (1 << TIF_FSCHECK)
135 
136 /*
137  * work to do in syscall_trace_enter().  Also includes TIF_NOHZ for
138  * enter_from_user_mode()
139  */
140 #define _TIF_WORK_SYSCALL_ENTRY \
141         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
142          _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |       \
143          _TIF_NOHZ)
144 
145 /* flags to check in __switch_to() */
146 #define _TIF_WORK_CTXSW_BASE                                    \
147         (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP |           \
148          _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
149 
150 /*
151  * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
152  */
153 #ifdef CONFIG_SMP
154 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
155 #else
156 # define _TIF_WORK_CTXSW        (_TIF_WORK_CTXSW_BASE)
157 #endif
158 
159 #ifdef CONFIG_X86_IOPL_IOPERM
160 # define _TIF_WORK_CTXSW_PREV   (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
161                                  _TIF_IO_BITMAP)
162 #else
163 # define _TIF_WORK_CTXSW_PREV   (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
164 #endif
165 
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 extern void arch_task_cache_init(void);
243 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
244 extern void arch_release_task_struct(struct task_struct *tsk);
245 extern void arch_setup_new_exec(void);
246 #define arch_setup_new_exec arch_setup_new_exec
247 #endif  /* !__ASSEMBLY__ */
248 
249 #endif /* _ASM_X86_THREAD_INFO_H */
250 

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