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, but we neither
31 * access the extra members from NMI context, nor do we write such a
32 * frame at sp0 at all.
33 *
34 * x86_64 has a fixed-length stack frame.
35 */
36 #ifdef CONFIG_X86_32
37 # define TOP_OF_KERNEL_STACK_PADDING 8
38 #else
39 # define TOP_OF_KERNEL_STACK_PADDING 0
40 #endif
41
42 /*
43 * low level task data that entry.S needs immediate access to
44 * - this struct should fit entirely inside of one cache line
45 * - this struct shares the supervisor stack pages
46 */
47 #ifndef __ASSEMBLY__
48 struct task_struct;
49 struct exec_domain;
50 #include <asm/processor.h>
51 #include <linux/atomic.h>
52
53 struct thread_info {
54 struct task_struct *task; /* main task structure */
55 struct exec_domain *exec_domain; /* execution domain */
56 __u32 flags; /* low level flags */
57 __u32 status; /* thread synchronous flags */
58 __u32 cpu; /* current CPU */
59 int saved_preempt_count;
60 mm_segment_t addr_limit;
61 void __user *sysenter_return;
62 unsigned int sig_on_uaccess_error:1;
63 unsigned int uaccess_err:1; /* uaccess failed */
64 };
65
66 #define INIT_THREAD_INFO(tsk) \
67 { \
68 .task = &tsk, \
69 .exec_domain = &default_exec_domain, \
70 .flags = 0, \
71 .cpu = 0, \
72 .saved_preempt_count = INIT_PREEMPT_COUNT, \
73 .addr_limit = KERNEL_DS, \
74 }
75
76 #define init_thread_info (init_thread_union.thread_info)
77 #define init_stack (init_thread_union.stack)
78
79 #else /* !__ASSEMBLY__ */
80
81 #include <asm/asm-offsets.h>
82
83 #endif
84
85 /*
86 * thread information flags
87 * - these are process state flags that various assembly files
88 * may need to access
89 * - pending work-to-be-done flags are in LSW
90 * - other flags in MSW
91 * Warning: layout of LSW is hardcoded in entry.S
92 */
93 #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
94 #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
95 #define TIF_SIGPENDING 2 /* signal pending */
96 #define TIF_NEED_RESCHED 3 /* rescheduling necessary */
97 #define TIF_SINGLESTEP 4 /* reenable singlestep on user return*/
98 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */
99 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
100 #define TIF_SECCOMP 8 /* secure computing */
101 #define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
102 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
103 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
104 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
105 #define TIF_IA32 17 /* IA32 compatibility process */
106 #define TIF_FORK 18 /* ret_from_fork */
107 #define TIF_NOHZ 19 /* in adaptive nohz mode */
108 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
109 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
110 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
111 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
112 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
113 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
114 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
115 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
116 #define TIF_X32 30 /* 32-bit native x86-64 binary */
117
118 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
119 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
120 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
121 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
122 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
123 #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
124 #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
125 #define _TIF_SECCOMP (1 << TIF_SECCOMP)
126 #define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
127 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
128 #define _TIF_UPROBE (1 << TIF_UPROBE)
129 #define _TIF_NOTSC (1 << TIF_NOTSC)
130 #define _TIF_IA32 (1 << TIF_IA32)
131 #define _TIF_FORK (1 << TIF_FORK)
132 #define _TIF_NOHZ (1 << TIF_NOHZ)
133 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
134 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
135 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
136 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
137 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
138 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
139 #define _TIF_ADDR32 (1 << TIF_ADDR32)
140 #define _TIF_X32 (1 << TIF_X32)
141
142 /* work to do in syscall_trace_enter() */
143 #define _TIF_WORK_SYSCALL_ENTRY \
144 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
145 _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \
146 _TIF_NOHZ)
147
148 /* work to do in syscall_trace_leave() */
149 #define _TIF_WORK_SYSCALL_EXIT \
150 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP | \
151 _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)
152
153 /* work to do on interrupt/exception return */
154 #define _TIF_WORK_MASK \
155 (0x0000FFFF & \
156 ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \
157 _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
158
159 /* work to do on any return to user space */
160 #define _TIF_ALLWORK_MASK \
161 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
162 _TIF_NOHZ)
163
164 /* Only used for 64 bit */
165 #define _TIF_DO_NOTIFY_MASK \
166 (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \
167 _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE)
168
169 /* flags to check in __switch_to() */
170 #define _TIF_WORK_CTXSW \
171 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP)
172
173 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
174 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
175
176 #define STACK_WARN (THREAD_SIZE/8)
177 #define KERNEL_STACK_OFFSET (5*(BITS_PER_LONG/8))
178
179 /*
180 * macros/functions for gaining access to the thread information structure
181 *
182 * preempt_count needs to be 1 initially, until the scheduler is functional.
183 */
184 #ifndef __ASSEMBLY__
185
186 DECLARE_PER_CPU(unsigned long, kernel_stack);
187
current_thread_info(void)188 static inline struct thread_info *current_thread_info(void)
189 {
190 struct thread_info *ti;
191 ti = (void *)(this_cpu_read_stable(kernel_stack) +
192 KERNEL_STACK_OFFSET - THREAD_SIZE);
193 return ti;
194 }
195
196 /*
197 * Walks up the stack frames to make sure that the specified object is
198 * entirely contained by a single stack frame.
199 *
200 * Returns:
201 * 1 if within a frame
202 * -1 if placed across a frame boundary (or outside stack)
203 * 0 unable to determine (no frame pointers, etc)
204 */
arch_within_stack_frames(const void * const stack,const void * const stackend,const void * obj,unsigned long len)205 static inline int arch_within_stack_frames(const void * const stack,
206 const void * const stackend,
207 const void *obj, unsigned long len)
208 {
209 #if defined(CONFIG_FRAME_POINTER)
210 const void *frame = NULL;
211 const void *oldframe;
212
213 oldframe = __builtin_frame_address(1);
214 if (oldframe)
215 frame = __builtin_frame_address(2);
216 /*
217 * low ----------------------------------------------> high
218 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
219 * ^----------------^
220 * allow copies only within here
221 */
222 while (stack <= frame && frame < stackend) {
223 /*
224 * If obj + len extends past the last frame, this
225 * check won't pass and the next frame will be 0,
226 * causing us to bail out and correctly report
227 * the copy as invalid.
228 */
229 if (obj + len <= frame)
230 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
231 oldframe = frame;
232 frame = *(const void * const *)frame;
233 }
234 return -1;
235 #else
236 return 0;
237 #endif
238 }
239
240 #else /* !__ASSEMBLY__ */
241
242 /* how to get the thread information struct from ASM */
243 #define GET_THREAD_INFO(reg) \
244 _ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \
245 _ASM_SUB $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg ;
246
247 /*
248 * Same if PER_CPU_VAR(kernel_stack) is, perhaps with some offset, already in
249 * a certain register (to be used in assembler memory operands).
250 */
251 #define THREAD_INFO(reg, off) KERNEL_STACK_OFFSET+(off)-THREAD_SIZE(reg)
252
253 #endif
254
255 /*
256 * Thread-synchronous status.
257 *
258 * This is different from the flags in that nobody else
259 * ever touches our thread-synchronous status, so we don't
260 * have to worry about atomic accesses.
261 */
262 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
263 #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
264
265 #ifndef __ASSEMBLY__
266 #define HAVE_SET_RESTORE_SIGMASK 1
set_restore_sigmask(void)267 static inline void set_restore_sigmask(void)
268 {
269 struct thread_info *ti = current_thread_info();
270 ti->status |= TS_RESTORE_SIGMASK;
271 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
272 }
clear_restore_sigmask(void)273 static inline void clear_restore_sigmask(void)
274 {
275 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
276 }
test_restore_sigmask(void)277 static inline bool test_restore_sigmask(void)
278 {
279 return current_thread_info()->status & TS_RESTORE_SIGMASK;
280 }
test_and_clear_restore_sigmask(void)281 static inline bool test_and_clear_restore_sigmask(void)
282 {
283 struct thread_info *ti = current_thread_info();
284 if (!(ti->status & TS_RESTORE_SIGMASK))
285 return false;
286 ti->status &= ~TS_RESTORE_SIGMASK;
287 return true;
288 }
289
is_ia32_task(void)290 static inline bool is_ia32_task(void)
291 {
292 #ifdef CONFIG_X86_32
293 return true;
294 #endif
295 #ifdef CONFIG_IA32_EMULATION
296 if (current_thread_info()->status & TS_COMPAT)
297 return true;
298 #endif
299 return false;
300 }
301 #endif /* !__ASSEMBLY__ */
302
303 #ifndef __ASSEMBLY__
304 extern void arch_task_cache_init(void);
305 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
306 extern void arch_release_task_struct(struct task_struct *tsk);
307 #endif
308 #endif /* _ASM_X86_THREAD_INFO_H */
309