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_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_IA32		17	/* IA32 compatibility process */
95#define TIF_SLD			18	/* Restore split lock detection on context switch */
96#define TIF_NOTIFY_SIGNAL	19	/* signal notifications exist */
97#define TIF_MEMDIE		20	/* is terminating due to OOM killer */
98#define TIF_POLLING_NRFLAG	21	/* idle is polling for TIF_NEED_RESCHED */
99#define TIF_IO_BITMAP		22	/* uses I/O bitmap */
100#define TIF_FORCED_TF		24	/* true if TF in eflags artificially */
101#define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
102#define TIF_LAZY_MMU_UPDATES	27	/* task is updating the mmu lazily */
103#define TIF_SYSCALL_TRACEPOINT	28	/* syscall tracepoint instrumentation */
104#define TIF_ADDR32		29	/* 32-bit address space on 64 bits */
105#define TIF_X32			30	/* 32-bit native x86-64 binary */
106
107#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
108#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
109#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
110#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
111#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
112#define _TIF_SSBD		(1 << TIF_SSBD)
113#define _TIF_SYSCALL_EMU	(1 << TIF_SYSCALL_EMU)
114#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
115#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
116#define _TIF_SPEC_IB		(1 << TIF_SPEC_IB)
117#define _TIF_SPEC_FORCE_UPDATE	(1 << TIF_SPEC_FORCE_UPDATE)
118#define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
119#define _TIF_UPROBE		(1 << TIF_UPROBE)
120#define _TIF_PATCH_PENDING	(1 << TIF_PATCH_PENDING)
121#define _TIF_NEED_FPU_LOAD	(1 << TIF_NEED_FPU_LOAD)
122#define _TIF_NOCPUID		(1 << TIF_NOCPUID)
123#define _TIF_NOTSC		(1 << TIF_NOTSC)
124#define _TIF_IA32		(1 << TIF_IA32)
125#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
126#define _TIF_SLD		(1 << TIF_SLD)
127#define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
128#define _TIF_IO_BITMAP		(1 << TIF_IO_BITMAP)
129#define _TIF_FORCED_TF		(1 << TIF_FORCED_TF)
130#define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
131#define _TIF_LAZY_MMU_UPDATES	(1 << TIF_LAZY_MMU_UPDATES)
132#define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
133#define _TIF_ADDR32		(1 << TIF_ADDR32)
134#define _TIF_X32		(1 << TIF_X32)
135
136/* flags to check in __switch_to() */
137#define _TIF_WORK_CTXSW_BASE					\
138	(_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP |		\
139	 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE | _TIF_SLD)
140
141/*
142 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
143 */
144#ifdef CONFIG_SMP
145# define _TIF_WORK_CTXSW	(_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
146#else
147# define _TIF_WORK_CTXSW	(_TIF_WORK_CTXSW_BASE)
148#endif
149
150#ifdef CONFIG_X86_IOPL_IOPERM
151# define _TIF_WORK_CTXSW_PREV	(_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
152				 _TIF_IO_BITMAP)
153#else
154# define _TIF_WORK_CTXSW_PREV	(_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
155#endif
156
157#define _TIF_WORK_CTXSW_NEXT	(_TIF_WORK_CTXSW)
158
159#define STACK_WARN		(THREAD_SIZE/8)
160
161/*
162 * macros/functions for gaining access to the thread information structure
163 *
164 * preempt_count needs to be 1 initially, until the scheduler is functional.
165 */
166#ifndef __ASSEMBLY__
167
168/*
169 * Walks up the stack frames to make sure that the specified object is
170 * entirely contained by a single stack frame.
171 *
172 * Returns:
173 *	GOOD_FRAME	if within a frame
174 *	BAD_STACK	if placed across a frame boundary (or outside stack)
175 *	NOT_STACK	unable to determine (no frame pointers, etc)
176 */
177static inline int arch_within_stack_frames(const void * const stack,
178					   const void * const stackend,
179					   const void *obj, unsigned long len)
180{
181#if defined(CONFIG_FRAME_POINTER)
182	const void *frame = NULL;
183	const void *oldframe;
184
185	oldframe = __builtin_frame_address(1);
186	if (oldframe)
187		frame = __builtin_frame_address(2);
188	/*
189	 * low ----------------------------------------------> high
190	 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
191	 *                     ^----------------^
192	 *               allow copies only within here
193	 */
194	while (stack <= frame && frame < stackend) {
195		/*
196		 * If obj + len extends past the last frame, this
197		 * check won't pass and the next frame will be 0,
198		 * causing us to bail out and correctly report
199		 * the copy as invalid.
200		 */
201		if (obj + len <= frame)
202			return obj >= oldframe + 2 * sizeof(void *) ?
203				GOOD_FRAME : BAD_STACK;
204		oldframe = frame;
205		frame = *(const void * const *)frame;
206	}
207	return BAD_STACK;
208#else
209	return NOT_STACK;
210#endif
211}
212
213#else /* !__ASSEMBLY__ */
214
215#ifdef CONFIG_X86_64
216# define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
217#endif
218
219#endif
220
221/*
222 * Thread-synchronous status.
223 *
224 * This is different from the flags in that nobody else
225 * ever touches our thread-synchronous status, so we don't
226 * have to worry about atomic accesses.
227 */
228#define TS_COMPAT		0x0002	/* 32bit syscall active (64BIT)*/
229
230#ifndef __ASSEMBLY__
231#ifdef CONFIG_COMPAT
232#define TS_I386_REGS_POKED	0x0004	/* regs poked by 32-bit ptracer */
233#define TS_COMPAT_RESTART	0x0008
234
235#define arch_set_restart_data	arch_set_restart_data
236
237static inline void arch_set_restart_data(struct restart_block *restart)
238{
239	struct thread_info *ti = current_thread_info();
240	if (ti->status & TS_COMPAT)
241		ti->status |= TS_COMPAT_RESTART;
242	else
243		ti->status &= ~TS_COMPAT_RESTART;
244}
245#endif
246
247#ifdef CONFIG_X86_32
248#define in_ia32_syscall() true
249#else
250#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
251			   current_thread_info()->status & TS_COMPAT)
252#endif
253
254extern void arch_task_cache_init(void);
255extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
256extern void arch_release_task_struct(struct task_struct *tsk);
257extern void arch_setup_new_exec(void);
258#define arch_setup_new_exec arch_setup_new_exec
259#endif	/* !__ASSEMBLY__ */
260
261#endif /* _ASM_X86_THREAD_INFO_H */
262