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__
52struct task_struct;
53#include <asm/cpufeature.h>
54#include <linux/atomic.h>
55
56struct thread_info {
57 unsigned long flags; /* low level flags */
58 unsigned long syscall_work; /* SYSCALL_WORK_ flags */
59 u32 status; /* thread synchronous flags */
60#ifdef CONFIG_SMP
61 u32 cpu; /* current CPU */
62#endif
63};
64
65#define INIT_THREAD_INFO(tsk) \
66{ \
67 .flags = 0, \
68}
69
70#else /* !__ASSEMBLY__ */
71
72#include <asm/asm-offsets.h>
73
74#endif
75
76/*
77 * thread information flags
78 * - these are process state flags that various assembly files
79 * may need to access
80 */
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_SSBD 5 /* Speculative store bypass disable */
86#define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
87#define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */
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_NOTIFY_SIGNAL 17 /* signal notifications exist */
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_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */
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_ADDR32 29 /* 32-bit address space on 64 bits */
103
104#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
105#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
106#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
107#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
108#define _TIF_SSBD (1 << TIF_SSBD)
109#define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
110#define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH)
111#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
112#define _TIF_UPROBE (1 << TIF_UPROBE)
113#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
114#define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD)
115#define _TIF_NOCPUID (1 << TIF_NOCPUID)
116#define _TIF_NOTSC (1 << TIF_NOTSC)
117#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
118#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
119#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
120#define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
121#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
122#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
123#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
124#define _TIF_ADDR32 (1 << TIF_ADDR32)
125
126/* flags to check in __switch_to() */
127#define _TIF_WORK_CTXSW_BASE \
128 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \
129 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
130
131/*
132 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
133 */
134#ifdef CONFIG_SMP
135# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
136#else
137# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
138#endif
139
140#ifdef CONFIG_X86_IOPL_IOPERM
141# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
142 _TIF_IO_BITMAP)
143#else
144# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
145#endif
146
147#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
148
149#define STACK_WARN (THREAD_SIZE/8)
150
151/*
152 * macros/functions for gaining access to the thread information structure
153 *
154 * preempt_count needs to be 1 initially, until the scheduler is functional.
155 */
156#ifndef __ASSEMBLY__
157
158/*
159 * Walks up the stack frames to make sure that the specified object is
160 * entirely contained by a single stack frame.
161 *
162 * Returns:
163 * GOOD_FRAME if within a frame
164 * BAD_STACK if placed across a frame boundary (or outside stack)
165 * NOT_STACK unable to determine (no frame pointers, etc)
166 */
167static inline int arch_within_stack_frames(const void * const stack,
168 const void * const stackend,
169 const void *obj, unsigned long len)
170{
171#if defined(CONFIG_FRAME_POINTER)
172 const void *frame = NULL;
173 const void *oldframe;
174
175 oldframe = __builtin_frame_address(1);
176 if (oldframe)
177 frame = __builtin_frame_address(2);
178 /*
179 * low ----------------------------------------------> high
180 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
181 * ^----------------^
182 * allow copies only within here
183 */
184 while (stack <= frame && frame < stackend) {
185 /*
186 * If obj + len extends past the last frame, this
187 * check won't pass and the next frame will be 0,
188 * causing us to bail out and correctly report
189 * the copy as invalid.
190 */
191 if (obj + len <= frame)
192 return obj >= oldframe + 2 * sizeof(void *) ?
193 GOOD_FRAME : BAD_STACK;
194 oldframe = frame;
195 frame = *(const void * const *)frame;
196 }
197 return BAD_STACK;
198#else
199 return NOT_STACK;
200#endif
201}
202
203#endif /* !__ASSEMBLY__ */
204
205/*
206 * Thread-synchronous status.
207 *
208 * This is different from the flags in that nobody else
209 * ever touches our thread-synchronous status, so we don't
210 * have to worry about atomic accesses.
211 */
212#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
213
214#ifndef __ASSEMBLY__
215#ifdef CONFIG_COMPAT
216#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
217
218#define arch_set_restart_data(restart) \
219 do { restart->arch_data = current_thread_info()->status; } while (0)
220
221#endif
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_info()->status & TS_COMPAT)
228#endif
229
230extern void arch_task_cache_init(void);
231extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
232extern void arch_release_task_struct(struct task_struct *tsk);
233extern void arch_setup_new_exec(void);
234#define arch_setup_new_exec arch_setup_new_exec
235#endif /* !__ASSEMBLY__ */
236
237#endif /* _ASM_X86_THREAD_INFO_H */
238

source code of linux/arch/x86/include/asm/thread_info.h