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1/* thread_info.h: low-level thread information
2 *
3 * Copyright (C) 2002 David Howells (dhowells@redhat.com)
4 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
5 */
6
7#ifndef _ASM_X86_THREAD_INFO_H
8#define _ASM_X86_THREAD_INFO_H
9
10#include <linux/compiler.h>
11#include <asm/page.h>
12#include <asm/percpu.h>
13#include <asm/types.h>
14
15/*
16 * TOP_OF_KERNEL_STACK_PADDING is a number of unused bytes that we
17 * reserve at the top of the kernel stack. We do it because of a nasty
18 * 32-bit corner case. On x86_32, the hardware stack frame is
19 * variable-length. Except for vm86 mode, struct pt_regs assumes a
20 * maximum-length frame. If we enter from CPL 0, the top 8 bytes of
21 * pt_regs don't actually exist. Ordinarily this doesn't matter, but it
22 * does in at least one case:
23 *
24 * If we take an NMI early enough in SYSENTER, then we can end up with
25 * pt_regs that extends above sp0. On the way out, in the espfix code,
26 * we can read the saved SS value, but that value will be above sp0.
27 * Without this offset, that can result in a page fault. (We are
28 * careful that, in this case, the value we read doesn't matter.)
29 *
30 * In vm86 mode, the hardware frame is much longer still, so add 16
31 * bytes to make room for the real-mode segments.
32 *
33 * x86_64 has a fixed-length stack frame.
34 */
35#ifdef CONFIG_X86_32
36# ifdef CONFIG_VM86
37# define TOP_OF_KERNEL_STACK_PADDING 16
38# else
39# define TOP_OF_KERNEL_STACK_PADDING 8
40# endif
41#else
42# define TOP_OF_KERNEL_STACK_PADDING 0
43#endif
44
45/*
46 * low level task data that entry.S needs immediate access to
47 * - this struct should fit entirely inside of one cache line
48 * - this struct shares the supervisor stack pages
49 */
50#ifndef __ASSEMBLY__
51struct task_struct;
52#include <asm/cpufeature.h>
53#include <linux/atomic.h>
54
55struct thread_info {
56 struct task_struct *task; /* main task structure */
57 __u32 flags; /* low level flags */
58 __u32 status; /* thread synchronous flags */
59 __u32 cpu; /* current CPU */
60 mm_segment_t addr_limit;
61 unsigned int sig_on_uaccess_error:1;
62 unsigned int uaccess_err:1; /* uaccess failed */
63};
64
65#define INIT_THREAD_INFO(tsk) \
66{ \
67 .task = &tsk, \
68 .flags = 0, \
69 .cpu = 0, \
70 .addr_limit = KERNEL_DS, \
71}
72
73#define init_thread_info (init_thread_union.thread_info)
74#define init_stack (init_thread_union.stack)
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 * - pending work-to-be-done flags are in LSW
87 * - other flags in MSW
88 * Warning: layout of LSW is hardcoded in entry.S
89 */
90#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
91#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
92#define TIF_SIGPENDING 2 /* signal pending */
93#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
94#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
95#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
96#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
97#define TIF_SECCOMP 8 /* secure computing */
98#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
99#define TIF_UPROBE 12 /* breakpointed or singlestepping */
100#define TIF_NOTSC 16 /* TSC is not accessible in userland */
101#define TIF_IA32 17 /* IA32 compatibility process */
102#define TIF_FORK 18 /* ret_from_fork */
103#define TIF_NOHZ 19 /* in adaptive nohz mode */
104#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
105#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
106#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
107#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
108#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
109#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
110#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
111#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
112#define TIF_X32 30 /* 32-bit native x86-64 binary */
113
114#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
115#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
116#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
117#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
118#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
119#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
120#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
121#define _TIF_SECCOMP (1 << TIF_SECCOMP)
122#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
123#define _TIF_UPROBE (1 << TIF_UPROBE)
124#define _TIF_NOTSC (1 << TIF_NOTSC)
125#define _TIF_IA32 (1 << TIF_IA32)
126#define _TIF_FORK (1 << TIF_FORK)
127#define _TIF_NOHZ (1 << TIF_NOHZ)
128#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
129#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
130#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
131#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
132#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
133#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
134#define _TIF_ADDR32 (1 << TIF_ADDR32)
135#define _TIF_X32 (1 << TIF_X32)
136
137/*
138 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
139 * enter_from_user_mode()
140 */
141#define _TIF_WORK_SYSCALL_ENTRY \
142 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
143 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
144 _TIF_NOHZ)
145
146/* work to do on any return to user space */
147#define _TIF_ALLWORK_MASK \
148 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
149 _TIF_NOHZ)
150
151/* flags to check in __switch_to() */
152#define _TIF_WORK_CTXSW \
153 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
154
155#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
156#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
157
158#define STACK_WARN (THREAD_SIZE/8)
159
160/*
161 * macros/functions for gaining access to the thread information structure
162 *
163 * preempt_count needs to be 1 initially, until the scheduler is functional.
164 */
165#ifndef __ASSEMBLY__
166
167static inline struct thread_info *current_thread_info(void)
168{
169 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
170}
171
172static inline unsigned long current_stack_pointer(void)
173{
174 unsigned long sp;
175#ifdef CONFIG_X86_64
176 asm("mov %%rsp,%0" : "=g" (sp));
177#else
178 asm("mov %%esp,%0" : "=g" (sp));
179#endif
180 return sp;
181}
182
183#else /* !__ASSEMBLY__ */
184
185#ifdef CONFIG_X86_64
186# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
187#endif
188
189/* Load thread_info address into "reg" */
190#define GET_THREAD_INFO(reg) \
191 _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
192 _ASM_SUB $(THREAD_SIZE),reg ;
193
194/*
195 * ASM operand which evaluates to a 'thread_info' address of
196 * the current task, if it is known that "reg" is exactly "off"
197 * bytes below the top of the stack currently.
198 *
199 * ( The kernel stack's size is known at build time, it is usually
200 * 2 or 4 pages, and the bottom of the kernel stack contains
201 * the thread_info structure. So to access the thread_info very
202 * quickly from assembly code we can calculate down from the
203 * top of the kernel stack to the bottom, using constant,
204 * build-time calculations only. )
205 *
206 * For example, to fetch the current thread_info->flags value into %eax
207 * on x86-64 defconfig kernels, in syscall entry code where RSP is
208 * currently at exactly SIZEOF_PTREGS bytes away from the top of the
209 * stack:
210 *
211 * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
212 *
213 * will translate to:
214 *
215 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax
216 *
217 * which is below the current RSP by almost 16K.
218 */
219#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)
220
221#endif
222
223/*
224 * Thread-synchronous status.
225 *
226 * This is different from the flags in that nobody else
227 * ever touches our thread-synchronous status, so we don't
228 * have to worry about atomic accesses.
229 */
230#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
231#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
232
233#ifndef __ASSEMBLY__
234#define HAVE_SET_RESTORE_SIGMASK 1
235static inline void set_restore_sigmask(void)
236{
237 struct thread_info *ti = current_thread_info();
238 ti->status |= TS_RESTORE_SIGMASK;
239 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
240}
241static inline void clear_restore_sigmask(void)
242{
243 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
244}
245static inline bool test_restore_sigmask(void)
246{
247 return current_thread_info()->status & TS_RESTORE_SIGMASK;
248}
249static inline bool test_and_clear_restore_sigmask(void)
250{
251 struct thread_info *ti = current_thread_info();
252 if (!(ti->status & TS_RESTORE_SIGMASK))
253 return false;
254 ti->status &= ~TS_RESTORE_SIGMASK;
255 return true;
256}
257
258static inline bool is_ia32_task(void)
259{
260#ifdef CONFIG_X86_32
261 return true;
262#endif
263#ifdef CONFIG_IA32_EMULATION
264 if (current_thread_info()->status & TS_COMPAT)
265 return true;
266#endif
267 return false;
268}
269
270/*
271 * Force syscall return via IRET by making it look as if there was
272 * some work pending. IRET is our most capable (but slowest) syscall
273 * return path, which is able to restore modified SS, CS and certain
274 * EFLAGS values that other (fast) syscall return instructions
275 * are not able to restore properly.
276 */
277#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
278
279extern void arch_task_cache_init(void);
280extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
281extern void arch_release_task_struct(struct task_struct *tsk);
282#endif /* !__ASSEMBLY__ */
283
284#endif /* _ASM_X86_THREAD_INFO_H */
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 unsigned long syscall_work; /* SYSCALL_WORK_ flags */
59 u32 status; /* thread synchronous flags */
60#ifdef CONFIG_SMP
61 u32 cpu; /* current CPU */
62#endif
63};
64
65#define INIT_THREAD_INFO(tsk) \
66{ \
67 .flags = 0, \
68}
69
70#else /* !__ASSEMBLY__ */
71
72#include <asm/asm-offsets.h>
73
74#endif
75
76/*
77 * thread information flags
78 * - these are process state flags that various assembly files
79 * may need to access
80 */
81#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
82#define TIF_SIGPENDING 2 /* signal pending */
83#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
84#define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
85#define TIF_SSBD 5 /* Speculative store bypass disable */
86#define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
87#define TIF_SPEC_L1D_FLUSH 10 /* Flush L1D on mm switches (processes) */
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_NOTIFY_SIGNAL 17 /* signal notifications exist */
95#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
96#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
97#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
98#define TIF_SPEC_FORCE_UPDATE 23 /* Force speculation MSR update in context switch */
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_ADDR32 29 /* 32-bit address space on 64 bits */
103
104#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
105#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
106#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
107#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
108#define _TIF_SSBD (1 << TIF_SSBD)
109#define _TIF_SPEC_IB (1 << TIF_SPEC_IB)
110#define _TIF_SPEC_L1D_FLUSH (1 << TIF_SPEC_L1D_FLUSH)
111#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
112#define _TIF_UPROBE (1 << TIF_UPROBE)
113#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
114#define _TIF_NEED_FPU_LOAD (1 << TIF_NEED_FPU_LOAD)
115#define _TIF_NOCPUID (1 << TIF_NOCPUID)
116#define _TIF_NOTSC (1 << TIF_NOTSC)
117#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
118#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
119#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
120#define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
121#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
122#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
123#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
124#define _TIF_ADDR32 (1 << TIF_ADDR32)
125
126/* flags to check in __switch_to() */
127#define _TIF_WORK_CTXSW_BASE \
128 (_TIF_NOCPUID | _TIF_NOTSC | _TIF_BLOCKSTEP | \
129 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
130
131/*
132 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
133 */
134#ifdef CONFIG_SMP
135# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
136#else
137# define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
138#endif
139
140#ifdef CONFIG_X86_IOPL_IOPERM
141# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY | \
142 _TIF_IO_BITMAP)
143#else
144# define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW| _TIF_USER_RETURN_NOTIFY)
145#endif
146
147#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
148
149#define STACK_WARN (THREAD_SIZE/8)
150
151/*
152 * macros/functions for gaining access to the thread information structure
153 *
154 * preempt_count needs to be 1 initially, until the scheduler is functional.
155 */
156#ifndef __ASSEMBLY__
157
158/*
159 * Walks up the stack frames to make sure that the specified object is
160 * entirely contained by a single stack frame.
161 *
162 * Returns:
163 * GOOD_FRAME if within a frame
164 * BAD_STACK if placed across a frame boundary (or outside stack)
165 * NOT_STACK unable to determine (no frame pointers, etc)
166 *
167 * This function reads pointers from the stack and dereferences them. The
168 * pointers may not have their KMSAN shadow set up properly, which may result
169 * in false positive reports. Disable instrumentation to avoid those.
170 */
171__no_kmsan_checks
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#endif /* !__ASSEMBLY__ */
209
210/*
211 * Thread-synchronous status.
212 *
213 * This is different from the flags in that nobody else
214 * ever touches our thread-synchronous status, so we don't
215 * have to worry about atomic accesses.
216 */
217#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
218
219#ifndef __ASSEMBLY__
220#ifdef CONFIG_COMPAT
221#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
222
223#define arch_set_restart_data(restart) \
224 do { restart->arch_data = current_thread_info()->status; } while (0)
225
226#endif
227
228#ifdef CONFIG_X86_32
229#define in_ia32_syscall() true
230#else
231#define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
232 current_thread_info()->status & TS_COMPAT)
233#endif
234
235extern void arch_setup_new_exec(void);
236#define arch_setup_new_exec arch_setup_new_exec
237#endif /* !__ASSEMBLY__ */
238
239#endif /* _ASM_X86_THREAD_INFO_H */