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 /* Reduced data speculation */
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_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
87#define TIF_UPROBE 12 /* breakpointed or singlestepping */
88#define TIF_PATCH_PENDING 13 /* pending live patching update */
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_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#define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
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_NEED_RESCHED (1 << TIF_NEED_RESCHED)
108#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
109#define _TIF_SSBD (1 << TIF_SSBD)
110#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
111#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
112#define _TIF_SECCOMP (1 << TIF_SECCOMP)
113#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
114#define _TIF_UPROBE (1 << TIF_UPROBE)
115#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
116#define _TIF_NOCPUID (1 << TIF_NOCPUID)
117#define _TIF_NOTSC (1 << TIF_NOTSC)
118#define _TIF_IA32 (1 << TIF_IA32)
119#define _TIF_NOHZ (1 << TIF_NOHZ)
120#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
121#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
122#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
123#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
124#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
125#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
126#define _TIF_ADDR32 (1 << TIF_ADDR32)
127#define _TIF_X32 (1 << TIF_X32)
128#define _TIF_FSCHECK (1 << TIF_FSCHECK)
129
130/*
131 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
132 * enter_from_user_mode()
133 */
134#define _TIF_WORK_SYSCALL_ENTRY \
135 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
136 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
137 _TIF_NOHZ)
138
139/* work to do on any return to user space */
140#define _TIF_ALLWORK_MASK \
141 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
142 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \
143 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \
144 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT | \
145 _TIF_FSCHECK)
146
147/* flags to check in __switch_to() */
148#define _TIF_WORK_CTXSW \
149 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP|_TIF_SSBD)
150
151#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
152#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
153
154#define STACK_WARN (THREAD_SIZE/8)
155
156/*
157 * macros/functions for gaining access to the thread information structure
158 *
159 * preempt_count needs to be 1 initially, until the scheduler is functional.
160 */
161#ifndef __ASSEMBLY__
162
163/*
164 * Walks up the stack frames to make sure that the specified object is
165 * entirely contained by a single stack frame.
166 *
167 * Returns:
168 * GOOD_FRAME if within a frame
169 * BAD_STACK if placed across a frame boundary (or outside stack)
170 * NOT_STACK unable to determine (no frame pointers, etc)
171 */
172static inline int arch_within_stack_frames(const void * const stack,
173 const void * const stackend,
174 const void *obj, unsigned long len)
175{
176#if defined(CONFIG_FRAME_POINTER)
177 const void *frame = NULL;
178 const void *oldframe;
179
180 oldframe = __builtin_frame_address(1);
181 if (oldframe)
182 frame = __builtin_frame_address(2);
183 /*
184 * low ----------------------------------------------> high
185 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
186 * ^----------------^
187 * allow copies only within here
188 */
189 while (stack <= frame && frame < stackend) {
190 /*
191 * If obj + len extends past the last frame, this
192 * check won't pass and the next frame will be 0,
193 * causing us to bail out and correctly report
194 * the copy as invalid.
195 */
196 if (obj + len <= frame)
197 return obj >= oldframe + 2 * sizeof(void *) ?
198 GOOD_FRAME : BAD_STACK;
199 oldframe = frame;
200 frame = *(const void * const *)frame;
201 }
202 return BAD_STACK;
203#else
204 return NOT_STACK;
205#endif
206}
207
208#else /* !__ASSEMBLY__ */
209
210#ifdef CONFIG_X86_64
211# define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
212#endif
213
214#endif
215
216#ifdef CONFIG_COMPAT
217#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
218#endif
219#ifndef __ASSEMBLY__
220
221#ifdef CONFIG_X86_32
222#define in_ia32_syscall() true
223#else
224#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
225 current_thread_info()->status & TS_COMPAT)
226#endif
227
228/*
229 * Force syscall return via IRET by making it look as if there was
230 * some work pending. IRET is our most capable (but slowest) syscall
231 * return path, which is able to restore modified SS, CS and certain
232 * EFLAGS values that other (fast) syscall return instructions
233 * are not able to restore properly.
234 */
235#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
236
237extern void arch_task_cache_init(void);
238extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
239extern void arch_release_task_struct(struct task_struct *tsk);
240extern void arch_setup_new_exec(void);
241#define arch_setup_new_exec arch_setup_new_exec
242#endif /* !__ASSEMBLY__ */
243
244#endif /* _ASM_X86_THREAD_INFO_H */
245