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 */
arch_within_stack_frames(const void * const stack,const void * const stackend,const void * obj,unsigned long len)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 #endif /* !__ASSEMBLY__ */
201
202 /*
203 * Thread-synchronous status.
204 *
205 * This is different from the flags in that nobody else
206 * ever touches our thread-synchronous status, so we don't
207 * have to worry about atomic accesses.
208 */
209 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
210
211 #ifndef __ASSEMBLY__
212 #ifdef CONFIG_COMPAT
213 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
214
215 #define arch_set_restart_data(restart) \
216 do { restart->arch_data = current_thread_info()->status; } while (0)
217
218 #endif
219
220 #ifdef CONFIG_X86_32
221 #define in_ia32_syscall() true
222 #else
223 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
224 current_thread_info()->status & TS_COMPAT)
225 #endif
226
227 extern void arch_task_cache_init(void);
228 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
229 extern void arch_release_task_struct(struct task_struct *tsk);
230 extern void arch_setup_new_exec(void);
231 #define arch_setup_new_exec arch_setup_new_exec
232 #endif /* !__ASSEMBLY__ */
233
234 #endif /* _ASM_X86_THREAD_INFO_H */
235