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 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_NOHZ 19 /* in adaptive nohz mode */
96 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
97 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
98 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
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_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
103 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
104 #define TIF_X32 30 /* 32-bit native x86-64 binary */
105 #define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
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_NOHZ (1 << TIF_NOHZ)
126 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
127 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
128 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
129 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
130 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
131 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
132 #define _TIF_ADDR32 (1 << TIF_ADDR32)
133 #define _TIF_X32 (1 << TIF_X32)
134 #define _TIF_FSCHECK (1 << TIF_FSCHECK)
135
136 /*
137 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
138 * enter_from_user_mode()
139 */
140 #define _TIF_WORK_SYSCALL_ENTRY \
141 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
142 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
143 _TIF_NOHZ)
144
145 /* flags to check in __switch_to() */
146 #define _TIF_WORK_CTXSW_BASE \
147 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP| \
148 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
149
150 /*
151 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
152 */
153 #ifdef CONFIG_SMP
154 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
155 #else
156 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
157 #endif
158
159 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
160 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
161
162 #define STACK_WARN (THREAD_SIZE/8)
163
164 /*
165 * macros/functions for gaining access to the thread information structure
166 *
167 * preempt_count needs to be 1 initially, until the scheduler is functional.
168 */
169 #ifndef __ASSEMBLY__
170
171 /*
172 * Walks up the stack frames to make sure that the specified object is
173 * entirely contained by a single stack frame.
174 *
175 * Returns:
176 * GOOD_FRAME if within a frame
177 * BAD_STACK if placed across a frame boundary (or outside stack)
178 * NOT_STACK unable to determine (no frame pointers, etc)
179 */
180 static inline int arch_within_stack_frames(const void * const stack,
181 const void * const stackend,
182 const void *obj, unsigned long len)
183 {
184 #if defined(CONFIG_FRAME_POINTER)
185 const void *frame = NULL;
186 const void *oldframe;
187
188 oldframe = __builtin_frame_address(1);
189 if (oldframe)
190 frame = __builtin_frame_address(2);
191 /*
192 * low ----------------------------------------------> high
193 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
194 * ^----------------^
195 * allow copies only within here
196 */
197 while (stack <= frame && frame < stackend) {
198 /*
199 * If obj + len extends past the last frame, this
200 * check won't pass and the next frame will be 0,
201 * causing us to bail out and correctly report
202 * the copy as invalid.
203 */
204 if (obj + len <= frame)
205 return obj >= oldframe + 2 * sizeof(void *) ?
206 GOOD_FRAME : BAD_STACK;
207 oldframe = frame;
208 frame = *(const void * const *)frame;
209 }
210 return BAD_STACK;
211 #else
212 return NOT_STACK;
213 #endif
214 }
215
216 #else /* !__ASSEMBLY__ */
217
218 #ifdef CONFIG_X86_64
219 # define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
220 #endif
221
222 #endif
223
224 #ifdef CONFIG_COMPAT
225 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
226 #endif
227 #ifndef __ASSEMBLY__
228
229 #ifdef CONFIG_X86_32
230 #define in_ia32_syscall() true
231 #else
232 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
233 current_thread_info()->status & TS_COMPAT)
234 #endif
235
236 /*
237 * Force syscall return via IRET by making it look as if there was
238 * some work pending. IRET is our most capable (but slowest) syscall
239 * return path, which is able to restore modified SS, CS and certain
240 * EFLAGS values that other (fast) syscall return instructions
241 * are not able to restore properly.
242 */
243 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
244
245 extern void arch_task_cache_init(void);
246 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
247 extern void arch_release_task_struct(struct task_struct *tsk);
248 extern void arch_setup_new_exec(void);
249 #define arch_setup_new_exec arch_setup_new_exec
250 #endif /* !__ASSEMBLY__ */
251
252 #endif /* _ASM_X86_THREAD_INFO_H */