1 /* thread_info.h: low-level thread information
3 * Copyright (C) 2002 David Howells (dhowells@redhat.com)
4 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
7 #ifndef _ASM_X86_THREAD_INFO_H
8 #define _ASM_X86_THREAD_INFO_H
10 #include <linux/compiler.h>
12 #include <asm/percpu.h>
13 #include <asm/types.h>
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:
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.)
30 * In vm86 mode, the hardware frame is much longer still, so add 16
31 * bytes to make room for the real-mode segments.
33 * x86_64 has a fixed-length stack frame.
37 # define TOP_OF_KERNEL_STACK_PADDING 16
39 # define TOP_OF_KERNEL_STACK_PADDING 8
42 # define TOP_OF_KERNEL_STACK_PADDING 0
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
52 #include <asm/cpufeature.h>
53 #include <linux/atomic.h>
56 unsigned long flags; /* low level flags */
57 u32 status; /* thread synchronous flags */
60 #define INIT_THREAD_INFO(tsk) \
65 #define init_stack (init_thread_union.stack)
67 #else /* !__ASSEMBLY__ */
69 #include <asm/asm-offsets.h>
74 * thread information flags
75 * - these are process state flags that various assembly files
77 * - pending work-to-be-done flags are in LSW
78 * - other flags in MSW
79 * Warning: layout of LSW is hardcoded in entry.S
81 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
82 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
83 #define TIF_SIGPENDING 2 /* signal pending */
84 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */
85 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
86 #define TIF_SSBD 5 /* Speculative store bypass disable */
87 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */
88 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
89 #define TIF_SECCOMP 8 /* secure computing */
90 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
91 #define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */
92 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
93 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
94 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
95 #define TIF_IA32 17 /* IA32 compatibility process */
96 #define TIF_NOHZ 19 /* in adaptive nohz mode */
97 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
98 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
99 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
100 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
101 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
102 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
103 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
104 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
105 #define TIF_X32 30 /* 32-bit native x86-64 binary */
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_NOTSC (1 << TIF_NOTSC)
121 #define _TIF_IA32 (1 << TIF_IA32)
122 #define _TIF_NOHZ (1 << TIF_NOHZ)
123 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
124 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
125 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
126 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
127 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
128 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
129 #define _TIF_ADDR32 (1 << TIF_ADDR32)
130 #define _TIF_X32 (1 << TIF_X32)
133 * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
134 * enter_from_user_mode()
136 #define _TIF_WORK_SYSCALL_ENTRY \
137 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
138 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
141 /* work to do on any return to user space */
142 #define _TIF_ALLWORK_MASK \
143 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
146 /* flags to check in __switch_to() */
147 #define _TIF_WORK_CTXSW_BASE \
148 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP| \
149 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
152 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
155 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
157 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
160 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
161 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
163 #define STACK_WARN (THREAD_SIZE/8)
166 * macros/functions for gaining access to the thread information structure
168 * preempt_count needs to be 1 initially, until the scheduler is functional.
173 * Walks up the stack frames to make sure that the specified object is
174 * entirely contained by a single stack frame.
177 * 1 if within a frame
178 * -1 if placed across a frame boundary (or outside stack)
179 * 0 unable to determine (no frame pointers, etc)
181 static inline int arch_within_stack_frames(const void * const stack,
182 const void * const stackend,
183 const void *obj, unsigned long len)
185 #if defined(CONFIG_FRAME_POINTER)
186 const void *frame = NULL;
187 const void *oldframe;
189 oldframe = __builtin_frame_address(1);
191 frame = __builtin_frame_address(2);
193 * low ----------------------------------------------> high
194 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
196 * allow copies only within here
198 while (stack <= frame && frame < stackend) {
200 * If obj + len extends past the last frame, this
201 * check won't pass and the next frame will be 0,
202 * causing us to bail out and correctly report
203 * the copy as invalid.
205 if (obj + len <= frame)
206 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
208 frame = *(const void * const *)frame;
216 #else /* !__ASSEMBLY__ */
219 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
225 * Thread-synchronous status.
227 * This is different from the flags in that nobody else
228 * ever touches our thread-synchronous status, so we don't
229 * have to worry about atomic accesses.
231 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
235 #define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */
236 #define TS_COMPAT_RESTART 0x0008
238 #define arch_set_restart_data arch_set_restart_data
240 static inline void arch_set_restart_data(struct restart_block *restart)
242 struct thread_info *ti = current_thread_info();
243 if (ti->status & TS_COMPAT)
244 ti->status |= TS_COMPAT_RESTART;
246 ti->status &= ~TS_COMPAT_RESTART;
251 #define in_ia32_syscall() true
253 #define in_ia32_syscall() (IS_ENABLED(CONFIG_IA32_EMULATION) && \
254 current_thread_info()->status & TS_COMPAT)
258 * Force syscall return via IRET by making it look as if there was
259 * some work pending. IRET is our most capable (but slowest) syscall
260 * return path, which is able to restore modified SS, CS and certain
261 * EFLAGS values that other (fast) syscall return instructions
262 * are not able to restore properly.
264 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
266 extern void arch_task_cache_init(void);
267 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
268 extern void arch_release_task_struct(struct task_struct *tsk);
269 #endif /* !__ASSEMBLY__ */
271 #endif /* _ASM_X86_THREAD_INFO_H */