1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* thread_info.h: low-level thread information
3 *
4 * Copyright (C) 2002 David Howells ([email protected])
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, but it depends on whether
35 * or not FRED is enabled. Future versions of FRED might make this
36 * dynamic, but for now it is always 2 words longer.
37 */
38 #ifdef CONFIG_X86_32
39 # ifdef CONFIG_VM86
40 # define TOP_OF_KERNEL_STACK_PADDING 16
41 # else
42 # define TOP_OF_KERNEL_STACK_PADDING 8
43 # endif
44 #else /* x86-64 */
45 # ifdef CONFIG_X86_FRED
46 # define TOP_OF_KERNEL_STACK_PADDING (2 * 8)
47 # else
48 # define TOP_OF_KERNEL_STACK_PADDING 0
49 # endif
50 #endif
51
52 /*
53 * low level task data that entry.S needs immediate access to
54 * - this struct should fit entirely inside of one cache line
55 * - this struct shares the supervisor stack pages
56 */
57 #ifndef __ASSEMBLY__
58 struct task_struct;
59 #include <asm/cpufeature.h>
60 #include <linux/atomic.h>
61
62 struct thread_info {
63 unsigned long flags; /* low level flags */
64 unsigned long syscall_work; /* SYSCALL_WORK_ flags */
65 u32 status; /* thread synchronous flags */
66 #ifdef CONFIG_SMP
67 u32 cpu; /* current CPU */
68 #endif
69 };
70
71 #define INIT_THREAD_INFO(tsk) \
72 { \
73 .flags = 0, \
74 }
75
76 #else /* !__ASSEMBLY__ */
77
78 #include <asm/asm-offsets.h>
79
80 #endif
81
82 /*
83 * thread information flags
84 * - these are process state flags that various assembly files
85 * may need to access
86 */
87 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
88 #define TIF_SIGPENDING 2 /* signal pending */
89 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */
90 #define TIF_NEED_RESCHED_LAZY 4 /* Lazy rescheduling needed */
91 #define TIF_SINGLESTEP 5 /* reenable singlestep on user return*/
92 #define TIF_SSBD 6 /* Speculative store bypass disable */
93 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
94 #define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */
95 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
96 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
97 #define TIF_PATCH_PENDING 13 /* pending live patching update */
98 #define TIF_NEED_FPU_LOAD 14 /* load FPU on return to userspace */
99 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */
100 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
101 #define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */
102 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
103 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
104 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
105 #define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */
106 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
107 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
108 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
109 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
110
111 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
112 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
113 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
114 #define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY)
115 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
116 #define _TIF_SSBD (1 << TIF_SSBD)
117 #define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
118 #define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH)
119 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
120 #define _TIF_UPROBE (1 << TIF_UPROBE)
121 #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
122 #define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD)
123 #define _TIF_NOCPUID (1 << TIF_NOCPUID)
124 #define _TIF_NOTSC (1 << TIF_NOTSC)
125 #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
126 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
127 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
128 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
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_ADDR32 (1 << TIF_ADDR32)
133
134 /* flags to check in __switch_to() */
135 #define _TIF_WORK_CTXSW_BASE \
136 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \
137 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
138
139 /*
140 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
141 */
142 #ifdef CONFIG_SMP
143 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
144 #else
145 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
146 #endif
147
148 #ifdef CONFIG_X86_IOPL_IOPERM
149 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
150 _TIF_IO_BITMAP)
151 #else
152 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
153 #endif
154
155 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
156
157 #define STACK_WARN (THREAD_SIZE/8)
158
159 /*
160 * macros/functions for gaining access to the thread information structure
161 *
162 * preempt_count needs to be 1 initially, until the scheduler is functional.
163 */
164 #ifndef __ASSEMBLY__
165
166 /*
167 * Walks up the stack frames to make sure that the specified object is
168 * entirely contained by a single stack frame.
169 *
170 * Returns:
171 * GOOD_FRAME if within a frame
172 * BAD_STACK if placed across a frame boundary (or outside stack)
173 * NOT_STACK unable to determine (no frame pointers, etc)
174 *
175 * This function reads pointers from the stack and dereferences them. The
176 * pointers may not have their KMSAN shadow set up properly, which may result
177 * in false positive reports. Disable instrumentation to avoid those.
178 */
179 __no_kmsan_checks
arch_within_stack_frames(const void * const stack,const void * const stackend,const void * obj,unsigned long len)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 #endif /* !__ASSEMBLY__ */
217
218 /*
219 * Thread-synchronous status.
220 *
221 * This is different from the flags in that nobody else
222 * ever touches our thread-synchronous status, so we don't
223 * have to worry about atomic accesses.
224 */
225 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
226
227 #ifndef __ASSEMBLY__
228 #ifdef CONFIG_COMPAT
229 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
230
231 #define arch_set_restart_data(restart) \
232 do { restart->arch_data = current_thread_info()->status; } while (0)
233
234 #endif
235
236 #ifdef CONFIG_X86_32
237 #define in_ia32_syscall() true
238 #else
239 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
240 current_thread_info()->status & TS_COMPAT)
241 #endif
242
243 extern void arch_setup_new_exec(void);
244 #define arch_setup_new_exec arch_setup_new_exec
245 #endif /* !__ASSEMBLY__ */
246
247 #endif /* _ASM_X86_THREAD_INFO_H */
248