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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
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7#ifndef _ASM_X86_THREAD_INFO_H
8#define _ASM_X86_THREAD_INFO_H
2052e8d4 9
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10#include <linux/compiler.h>
11#include <asm/page.h>
198d208d 12#include <asm/percpu.h>
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13#include <asm/types.h>
14
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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 *
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30 * In vm86 mode, the hardware frame is much longer still, so add 16
31 * bytes to make room for the real-mode segments.
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32 *
33 * x86_64 has a fixed-length stack frame.
34 */
35#ifdef CONFIG_X86_32
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36# ifdef CONFIG_VM86
37# define TOP_OF_KERNEL_STACK_PADDING 16
38# else
39# define TOP_OF_KERNEL_STACK_PADDING 8
40# endif
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41#else
42# define TOP_OF_KERNEL_STACK_PADDING 0
43#endif
44
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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
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49 */
50#ifndef __ASSEMBLY__
006c484b 51struct task_struct;
cd4d09ec 52#include <asm/cpufeature.h>
60063497 53#include <linux/atomic.h>
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54
55struct thread_info {
56 struct task_struct *task; /* main task structure */
affa219b 57 __u32 flags; /* low level flags */
006c484b 58 __u32 status; /* thread synchronous flags */
2052e8d4 59 __u32 cpu; /* current CPU */
006c484b 60 mm_segment_t addr_limit;
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61 unsigned int sig_on_uaccess_error:1;
62 unsigned int uaccess_err:1; /* uaccess failed */
2052e8d4 63};
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64
65#define INIT_THREAD_INFO(tsk) \
66{ \
67 .task = &tsk, \
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68 .flags = 0, \
69 .cpu = 0, \
3351cc03 70 .addr_limit = KERNEL_DS, \
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71}
72
73#define init_thread_info (init_thread_union.thread_info)
74#define init_stack (init_thread_union.stack)
75
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76#else /* !__ASSEMBLY__ */
77
78#include <asm/asm-offsets.h>
79
80#endif
81
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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 */
59e52130 91#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
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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*/
e57549b0 95#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
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96#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
97#define TIF_SECCOMP 8 /* secure computing */
7c68af6e 98#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
0326f5a9 99#define TIF_UPROBE 12 /* breakpointed or singlestepping */
e57549b0 100#define TIF_NOTSC 16 /* TSC is not accessible in userland */
6bd33008 101#define TIF_IA32 17 /* IA32 compatibility process */
e57549b0 102#define TIF_FORK 18 /* ret_from_fork */
bf5a3c13 103#define TIF_NOHZ 19 /* in adaptive nohz mode */
0ddc9324 104#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
f80c5b39 105#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
e57549b0 106#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
e57549b0 107#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
ea8e61b7 108#define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
b407fc57 109#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
66700001 110#define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
6bd33008 111#define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
bb212724 112#define TIF_X32 30 /* 32-bit native x86-64 binary */
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113
114#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
59e52130 115#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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116#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
117#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
118#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
e57549b0 119#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
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120#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
121#define _TIF_SECCOMP (1 << TIF_SECCOMP)
7c68af6e 122#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
0326f5a9 123#define _TIF_UPROBE (1 << TIF_UPROBE)
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124#define _TIF_NOTSC (1 << TIF_NOTSC)
125#define _TIF_IA32 (1 << TIF_IA32)
126#define _TIF_FORK (1 << TIF_FORK)
bf5a3c13 127#define _TIF_NOHZ (1 << TIF_NOHZ)
f80c5b39 128#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
e57549b0 129#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
e57549b0 130#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
ea8e61b7 131#define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
b407fc57 132#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
66700001 133#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
6bd33008 134#define _TIF_ADDR32 (1 << TIF_ADDR32)
bb212724 135#define _TIF_X32 (1 << TIF_X32)
e57549b0 136
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137/* work to do in syscall_trace_enter() */
138#define _TIF_WORK_SYSCALL_ENTRY \
66700001 139 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
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140 _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \
141 _TIF_NOHZ)
d4d67150 142
00c1bb13 143/* work to do on any return to user space */
66700001 144#define _TIF_ALLWORK_MASK \
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145 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
146 _TIF_NOHZ)
00c1bb13 147
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148/* flags to check in __switch_to() */
149#define _TIF_WORK_CTXSW \
ea8e61b7 150 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
00c1bb13 151
7c68af6e 152#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
37f07655 153#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
00c1bb13 154
198d208d 155#define STACK_WARN (THREAD_SIZE/8)
b84200b3 156
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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
9af45651 164static inline struct thread_info *current_thread_info(void)
2052e8d4 165{
a7fcf28d 166 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
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167}
168
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169static inline unsigned long current_stack_pointer(void)
170{
171 unsigned long sp;
172#ifdef CONFIG_X86_64
173 asm("mov %%rsp,%0" : "=g" (sp));
174#else
175 asm("mov %%esp,%0" : "=g" (sp));
176#endif
177 return sp;
178}
179
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180#else /* !__ASSEMBLY__ */
181
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182#ifdef CONFIG_X86_64
183# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
184#endif
185
ef593260 186/* Load thread_info address into "reg" */
2052e8d4 187#define GET_THREAD_INFO(reg) \
63332a84 188 _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
ef593260 189 _ASM_SUB $(THREAD_SIZE),reg ;
2052e8d4 190
46db09d3 191/*
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192 * ASM operand which evaluates to a 'thread_info' address of
193 * the current task, if it is known that "reg" is exactly "off"
194 * bytes below the top of the stack currently.
195 *
196 * ( The kernel stack's size is known at build time, it is usually
197 * 2 or 4 pages, and the bottom of the kernel stack contains
198 * the thread_info structure. So to access the thread_info very
199 * quickly from assembly code we can calculate down from the
200 * top of the kernel stack to the bottom, using constant,
201 * build-time calculations only. )
202 *
203 * For example, to fetch the current thread_info->flags value into %eax
204 * on x86-64 defconfig kernels, in syscall entry code where RSP is
205 * currently at exactly SIZEOF_PTREGS bytes away from the top of the
206 * stack:
207 *
dca5b52a 208 * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
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209 *
210 * will translate to:
211 *
212 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax
213 *
214 * which is below the current RSP by almost 16K.
46db09d3 215 */
dca5b52a 216#define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)
46db09d3 217
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218#endif
219
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220/*
221 * Thread-synchronous status.
222 *
223 * This is different from the flags in that nobody else
224 * ever touches our thread-synchronous status, so we don't
225 * have to worry about atomic accesses.
226 */
f2ea3b1d 227#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
8a6c160a 228#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
2052e8d4 229
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230#ifndef __ASSEMBLY__
231#define HAVE_SET_RESTORE_SIGMASK 1
232static inline void set_restore_sigmask(void)
233{
234 struct thread_info *ti = current_thread_info();
235 ti->status |= TS_RESTORE_SIGMASK;
edd63a27 236 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
8a6c160a 237}
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238static inline void clear_restore_sigmask(void)
239{
240 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
241}
242static inline bool test_restore_sigmask(void)
243{
244 return current_thread_info()->status & TS_RESTORE_SIGMASK;
245}
246static inline bool test_and_clear_restore_sigmask(void)
247{
248 struct thread_info *ti = current_thread_info();
249 if (!(ti->status & TS_RESTORE_SIGMASK))
250 return false;
251 ti->status &= ~TS_RESTORE_SIGMASK;
252 return true;
253}
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254
255static inline bool is_ia32_task(void)
256{
257#ifdef CONFIG_X86_32
258 return true;
259#endif
260#ifdef CONFIG_IA32_EMULATION
261 if (current_thread_info()->status & TS_COMPAT)
262 return true;
263#endif
264 return false;
265}
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266
267/*
268 * Force syscall return via IRET by making it look as if there was
269 * some work pending. IRET is our most capable (but slowest) syscall
270 * return path, which is able to restore modified SS, CS and certain
271 * EFLAGS values that other (fast) syscall return instructions
272 * are not able to restore properly.
273 */
274#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
275
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276#endif /* !__ASSEMBLY__ */
277
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278#ifndef __ASSEMBLY__
279extern void arch_task_cache_init(void);
61c4628b 280extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
38e7c572 281extern void arch_release_task_struct(struct task_struct *tsk);
61c4628b 282#endif
1965aae3 283#endif /* _ASM_X86_THREAD_INFO_H */