1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* thread_info.h: low-level thread information
4 * Copyright (C) 2002 David Howells (dhowells@redhat.com)
5 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
8 #ifndef _ASM_X86_THREAD_INFO_H
9 #define _ASM_X86_THREAD_INFO_H
11 #include <linux/compiler.h>
13 #include <asm/percpu.h>
14 #include <asm/types.h>
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:
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.)
31 * In vm86 mode, the hardware frame is much longer still, so add 16
32 * bytes to make room for the real-mode segments.
34 * x86_64 has a fixed-length stack frame.
38 # define TOP_OF_KERNEL_STACK_PADDING 16
40 # define TOP_OF_KERNEL_STACK_PADDING 8
43 # define TOP_OF_KERNEL_STACK_PADDING 0
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
53 #include <asm/cpufeature.h>
54 #include <linux/atomic.h>
57 unsigned long flags; /* low level flags */
60 #define INIT_THREAD_INFO(tsk) \
65 #else /* !__ASSEMBLY__ */
67 #include <asm/asm-offsets.h>
72 * thread information flags
73 * - these are process state flags that various assembly files
76 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
77 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
78 #define TIF_SIGPENDING 2 /* signal pending */
79 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */
80 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
81 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */
82 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
83 #define TIF_SECCOMP 8 /* secure computing */
84 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
85 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
86 #define TIF_PATCH_PENDING 13 /* pending live patching update */
87 #define TIF_NOCPUID 15 /* CPUID is not accessible in userland */
88 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
89 #define TIF_IA32 17 /* IA32 compatibility process */
90 #define TIF_NOHZ 19 /* in adaptive nohz mode */
91 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
92 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
93 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
94 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
95 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
96 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
97 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
98 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
99 #define TIF_X32 30 /* 32-bit native x86-64 binary */
100 #define TIF_FSCHECK 31 /* Check FS is USER_DS on return */
102 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
103 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
104 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
105 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
106 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
107 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
108 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
109 #define _TIF_SECCOMP (1 << TIF_SECCOMP)
110 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
111 #define _TIF_UPROBE (1 << TIF_UPROBE)
112 #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING)
113 #define _TIF_NOCPUID (1 << TIF_NOCPUID)
114 #define _TIF_NOTSC (1 << TIF_NOTSC)
115 #define _TIF_IA32 (1 << TIF_IA32)
116 #define _TIF_NOHZ (1 << TIF_NOHZ)
117 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
118 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
119 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
120 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
121 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
122 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
123 #define _TIF_ADDR32 (1 << TIF_ADDR32)
124 #define _TIF_X32 (1 << TIF_X32)
125 #define _TIF_FSCHECK (1 << TIF_FSCHECK)
128 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
129 * enter_from_user_mode()
131 #define _TIF_WORK_SYSCALL_ENTRY \
132 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
133 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
136 /* work to do on any return to user space */
137 #define _TIF_ALLWORK_MASK \
138 (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
139 _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU | \
140 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \
141 _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT | \
144 /* flags to check in __switch_to() */
145 #define _TIF_WORK_CTXSW \
146 (_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP)
148 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
149 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
151 #define STACK_WARN (THREAD_SIZE/8)
154 * macros/functions for gaining access to the thread information structure
156 * preempt_count needs to be 1 initially, until the scheduler is functional.
161 * Walks up the stack frames to make sure that the specified object is
162 * entirely contained by a single stack frame.
165 * GOOD_FRAME if within a frame
166 * BAD_STACK if placed across a frame boundary (or outside stack)
167 * NOT_STACK unable to determine (no frame pointers, etc)
169 static inline int arch_within_stack_frames(const void * const stack,
170 const void * const stackend,
171 const void *obj, unsigned long len)
173 #if defined(CONFIG_FRAME_POINTER)
174 const void *frame = NULL;
175 const void *oldframe;
177 oldframe = __builtin_frame_address(1);
179 frame = __builtin_frame_address(2);
181 * low ----------------------------------------------> high
182 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
184 * allow copies only within here
186 while (stack <= frame && frame < stackend) {
188 * If obj + len extends past the last frame, this
189 * check won't pass and the next frame will be 0,
190 * causing us to bail out and correctly report
191 * the copy as invalid.
193 if (obj + len <= frame)
194 return obj >= oldframe + 2 * sizeof(void *) ?
195 GOOD_FRAME : BAD_STACK;
197 frame = *(const void * const *)frame;
205 #else /* !__ASSEMBLY__ */
208 # define cpu_current_top_of_stack (cpu_tss_rw + TSS_sp1)
214 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
219 #define in_ia32_syscall() true
221 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
222 current->thread.status & TS_COMPAT)
226 * Force syscall return via IRET by making it look as if there was
227 * some work pending. IRET is our most capable (but slowest) syscall
228 * return path, which is able to restore modified SS, CS and certain
229 * EFLAGS values that other (fast) syscall return instructions
230 * are not able to restore properly.
232 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
234 extern void arch_task_cache_init(void);
235 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
236 extern void arch_release_task_struct(struct task_struct *tsk);
237 extern void arch_setup_new_exec(void);
238 #define arch_setup_new_exec arch_setup_new_exec
239 #endif /* !__ASSEMBLY__ */
241 #endif /* _ASM_X86_THREAD_INFO_H */