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 u32 status; /* thread synchronous flags */
58 };
59
60 #define INIT_THREAD_INFO(tsk) \
61 { \
62 .flags = 0, \
63 }
64
65 #define init_stack (init_thread_union.stack)
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 * - pending work-to-be-done flags are in LSW
78 * - other flags in MSW
79 * Warning: layout of LSW is hardcoded in entry.S
80 */
81 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
82 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
83 #define TIF_SIGPENDING 2 /* signal pending */
84 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */
85 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
86 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */
87 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
88 #define TIF_SECCOMP 8 /* secure computing */
89 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
90 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
91 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
92 #define TIF_IA32 17 /* IA32 compatibility process */
93 #define TIF_NOHZ 19 /* in adaptive nohz mode */
94 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
95 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
96 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
97 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
98 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
99 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
100 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
101 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
102 #define TIF_X32 30 /* 32-bit native x86-64 binary */
103
104 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
105 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
106 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
107 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
108 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
109 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
110 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
111 #define _TIF_SECCOMP (1 << TIF_SECCOMP)
112 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
113 #define _TIF_UPROBE (1 << TIF_UPROBE)
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 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
138 _TIF_NOHZ)
139
140 /* flags to check in __switch_to() */
141 #define _TIF_WORK_CTXSW \
142 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
143
144 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
145 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
146
147 #define STACK_WARN (THREAD_SIZE/8)
148
149 /*
150 * macros/functions for gaining access to the thread information structure
151 *
152 * preempt_count needs to be 1 initially, until the scheduler is functional.
153 */
154 #ifndef __ASSEMBLY__
155
156 /*
157 * Walks up the stack frames to make sure that the specified object is
158 * entirely contained by a single stack frame.
159 *
160 * Returns:
161 * 1 if within a frame
162 * -1 if placed across a frame boundary (or outside stack)
163 * 0 unable to determine (no frame pointers, etc)
164 */
arch_within_stack_frames(const void * const stack,const void * const stackend,const void * obj,unsigned long len)165 static inline int arch_within_stack_frames(const void * const stack,
166 const void * const stackend,
167 const void *obj, unsigned long len)
168 {
169 #if defined(CONFIG_FRAME_POINTER)
170 const void *frame = NULL;
171 const void *oldframe;
172
173 oldframe = __builtin_frame_address(1);
174 if (oldframe)
175 frame = __builtin_frame_address(2);
176 /*
177 * low ----------------------------------------------> high
178 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
179 * ^----------------^
180 * allow copies only within here
181 */
182 while (stack <= frame && frame < stackend) {
183 /*
184 * If obj + len extends past the last frame, this
185 * check won't pass and the next frame will be 0,
186 * causing us to bail out and correctly report
187 * the copy as invalid.
188 */
189 if (obj + len <= frame)
190 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
191 oldframe = frame;
192 frame = *(const void * const *)frame;
193 }
194 return -1;
195 #else
196 return 0;
197 #endif
198 }
199
200 #else /* !__ASSEMBLY__ */
201
202 #ifdef CONFIG_X86_64
203 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
204 #endif
205
206 #endif
207
208 #ifdef CONFIG_COMPAT
209 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
210 #endif
211 #ifndef __ASSEMBLY__
212
213 #ifdef CONFIG_X86_32
214 #define in_ia32_syscall() true
215 #else
216 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
217 current_thread_info()->status & TS_COMPAT)
218 #endif
219
220 /*
221 * Force syscall return via IRET by making it look as if there was
222 * some work pending. IRET is our most capable (but slowest) syscall
223 * return path, which is able to restore modified SS, CS and certain
224 * EFLAGS values that other (fast) syscall return instructions
225 * are not able to restore properly.
226 */
227 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
228
229 extern void arch_task_cache_init(void);
230 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
231 extern void arch_release_task_struct(struct task_struct *tsk);
232 #endif /* !__ASSEMBLY__ */
233
234 #endif /* _ASM_X86_THREAD_INFO_H */
235