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, 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_SINGLESTEP 4 /* reenable singlestep on user return*/
91 #define TIF_SSBD 5 /* Speculative store bypass disable */
92 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
93 #define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */
94 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
95 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
96 #define TIF_PATCH_PENDING 13 /* pending live patching update */
97 #define TIF_NEED_FPU_LOAD 14 /* load FPU on return to userspace */
98 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */
99 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
100 #define TIF_NOTIFY_SIGNAL 17 /* signal notifications exist */
101 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
102 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
103 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
104 #define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */
105 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
106 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
107 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
108 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
109
110 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
111 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
112 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
113 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
114 #define _TIF_SSBD (1 << TIF_SSBD)
115 #define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
116 #define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH)
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_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD)
121 #define _TIF_NOCPUID (1 << TIF_NOCPUID)
122 #define _TIF_NOTSC (1 << TIF_NOTSC)
123 #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
124 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
125 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
126 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
127 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
128 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
129 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
130 #define _TIF_ADDR32 (1 << TIF_ADDR32)
131
132 /* flags to check in __switch_to() */
133 #define _TIF_WORK_CTXSW_BASE \
134 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \
135 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
136
137 /*
138 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
139 */
140 #ifdef CONFIG_SMP
141 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
142 #else
143 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
144 #endif
145
146 #ifdef CONFIG_X86_IOPL_IOPERM
147 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
148 _TIF_IO_BITMAP)
149 #else
150 # define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
151 #endif
152
153 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
154
155 #define STACK_WARN (THREAD_SIZE/8)
156
157 /*
158 * macros/functions for gaining access to the thread information structure
159 *
160 * preempt_count needs to be 1 initially, until the scheduler is functional.
161 */
162 #ifndef __ASSEMBLY__
163
164 /*
165 * Walks up the stack frames to make sure that the specified object is
166 * entirely contained by a single stack frame.
167 *
168 * Returns:
169 * GOOD_FRAME if within a frame
170 * BAD_STACK if placed across a frame boundary (or outside stack)
171 * NOT_STACK unable to determine (no frame pointers, etc)
172 *
173 * This function reads pointers from the stack and dereferences them. The
174 * pointers may not have their KMSAN shadow set up properly, which may result
175 * in false positive reports. Disable instrumentation to avoid those.
176 */
177 __no_kmsan_checks
178 static inline int arch_within_stack_frames(const void * const stack,
179 const void * const stackend,
180 const void *obj, unsigned long len)
181 {
182 #if defined(CONFIG_FRAME_POINTER)
183 const void *frame = NULL;
184 const void *oldframe;
185
186 oldframe = __builtin_frame_address(1);
187 if (oldframe)
188 frame = __builtin_frame_address(2);
189 /*
190 * low ----------------------------------------------> high
191 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
192 * ^----------------^
193 * allow copies only within here
194 */
195 while (stack <= frame && frame < stackend) {
196 /*
197 * If obj + len extends past the last frame, this
198 * check won't pass and the next frame will be 0,
199 * causing us to bail out and correctly report
200 * the copy as invalid.
201 */
202 if (obj + len <= frame)
203 return obj >= oldframe + 2 * sizeof(void *) ?
204 GOOD_FRAME : BAD_STACK;
205 oldframe = frame;
206 frame = *(const void * const *)frame;
207 }
208 return BAD_STACK;
209 #else
210 return NOT_STACK;
211 #endif
212 }
213
214 #endif /* !__ASSEMBLY__ */
215
216 /*
217 * Thread-synchronous status.
218 *
219 * This is different from the flags in that nobody else
220 * ever touches our thread-synchronous status, so we don't
221 * have to worry about atomic accesses.
222 */
223 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
224
225 #ifndef __ASSEMBLY__
226 #ifdef CONFIG_COMPAT
227 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
228
229 #define arch_set_restart_data(restart) \
230 do { restart->arch_data = current_thread_info()->status; } while (0)
231
232 #endif
233
234 #ifdef CONFIG_X86_32
235 #define in_ia32_syscall() true
236 #else
237 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
238 current_thread_info()->status & TS_COMPAT)
239 #endif
240
241 extern void arch_setup_new_exec(void);
242 #define arch_setup_new_exec arch_setup_new_exec
243 #endif /* !__ASSEMBLY__ */
244
245 #endif /* _ASM_X86_THREAD_INFO_H */
246
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