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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__
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 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_NOCPUID 15 /* CPUID is not accessible in userland */
92#define TIF_NOTSC 16 /* TSC is not accessible in userland */
93#define TIF_IA32 17 /* IA32 compatibility process */
94#define TIF_NOHZ 19 /* in adaptive nohz mode */
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_FORCED_TF 24 /* true if TF in eflags artificially */
99#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
100#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
101#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
102#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
103#define TIF_X32 30 /* 32-bit native x86-64 binary */
104#define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
105
106#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
107#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
108#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
109#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
110#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
111#define _TIF_SSBD (1 << TIF_SSBD)
112#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
113#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
114#define _TIF_SECCOMP (1 << TIF_SECCOMP)
115#define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
116#define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
117#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
118#define _TIF_UPROBE (1 << TIF_UPROBE)
119#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
120#define _TIF_NOCPUID (1 << TIF_NOCPUID)
121#define _TIF_NOTSC (1 << TIF_NOTSC)
122#define _TIF_IA32 (1 << TIF_IA32)
123#define _TIF_NOHZ (1 << TIF_NOHZ)
124#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
125#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
126#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
127#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
128#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
129#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
130#define _TIF_ADDR32 (1 << TIF_ADDR32)
131#define _TIF_X32 (1 << TIF_X32)
132#define _TIF_FSCHECK (1 << TIF_FSCHECK)
133
134/*
135 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
136 * enter_from_user_mode()
137 */
138#define _TIF_WORK_SYSCALL_ENTRY \
139 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
140 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
141 _TIF_NOHZ)
142
143/* work to do on any return to user space */
144#define _TIF_ALLWORK_MASK \
145 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
146 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \
147 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \
148 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT | \
149 _TIF_FSCHECK)
150
151/* flags to check in __switch_to() */
152#define _TIF_WORK_CTXSW_BASE \
153 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP| \
154 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
155
156/*
157 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
158 */
159#ifdef CONFIG_SMP
160# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
161#else
162# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
163#endif
164
165#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
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 */
186static 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/*
243 * Force syscall return via IRET by making it look as if there was
244 * some work pending. IRET is our most capable (but slowest) syscall
245 * return path, which is able to restore modified SS, CS and certain
246 * EFLAGS values that other (fast) syscall return instructions
247 * are not able to restore properly.
248 */
249#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
250
251extern void arch_task_cache_init(void);
252extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
253extern void arch_release_task_struct(struct task_struct *tsk);
254extern void arch_setup_new_exec(void);
255#define arch_setup_new_exec arch_setup_new_exec
256#endif /* !__ASSEMBLY__ */
257
258#endif /* _ASM_X86_THREAD_INFO_H */