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Linux/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 */
245 

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