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__
51 struct task_struct;
52 #include <asm/cpufeature.h>
53 #include <linux/atomic.h>
54
55 struct 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_SSBD 5 /* Speculative store bypass disable */
96 #define TIF_SYSCALL_EMU 6 /* syscall emulation active */
97 #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
98 #define TIF_SECCOMP 8 /* secure computing */
99 #define TIF_SPEC_IB 9 /* Indirect branch speculation mitigation */
100 #define TIF_SPEC_FORCE_UPDATE 10 /* Force speculation MSR update in context switch */
101 #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
102 #define TIF_UPROBE 12 /* breakpointed or singlestepping */
103 #define TIF_NOTSC 16 /* TSC is not accessible in userland */
104 #define TIF_IA32 17 /* IA32 compatibility process */
105 #define TIF_FORK 18 /* ret_from_fork */
106 #define TIF_NOHZ 19 /* in adaptive nohz mode */
107 #define TIF_MEMDIE 20 /* is terminating due to OOM killer */
108 #define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
109 #define TIF_IO_BITMAP 22 /* uses I/O bitmap */
110 #define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
111 #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */
112 #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
113 #define TIF_SYSCALL_TRACEPOINT 28 /* syscall tracepoint instrumentation */
114 #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */
115 #define TIF_X32 30 /* 32-bit native x86-64 binary */
116
117 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
118 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
119 #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
120 #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
121 #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
122 #define _TIF_SSBD (1 << TIF_SSBD)
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_SPEC_IB (1 << TIF_SPEC_IB)
127 #define _TIF_SPEC_FORCE_UPDATE (1 << TIF_SPEC_FORCE_UPDATE)
128 #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
129 #define _TIF_UPROBE (1 << TIF_UPROBE)
130 #define _TIF_NOTSC (1 << TIF_NOTSC)
131 #define _TIF_IA32 (1 << TIF_IA32)
132 #define _TIF_FORK (1 << TIF_FORK)
133 #define _TIF_NOHZ (1 << TIF_NOHZ)
134 #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
135 #define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
136 #define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
137 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
138 #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
139 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
140 #define _TIF_ADDR32 (1 << TIF_ADDR32)
141 #define _TIF_X32 (1 << TIF_X32)
142
143 /* work to do in syscall_trace_enter() */
144 #define _TIF_WORK_SYSCALL_ENTRY \
145 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
146 _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT | \
147 _TIF_NOHZ)
148
149 /* work to do on any return to user space */
150 #define _TIF_ALLWORK_MASK \
151 ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
152 _TIF_NOHZ)
153
154 /* flags to check in __switch_to() */
155 #define _TIF_WORK_CTXSW_BASE \
156 (_TIF_IO_BITMAP|_TIF_NOTSC|_TIF_BLOCKSTEP| \
157 _TIF_SSBD | _TIF_SPEC_FORCE_UPDATE)
158
159 /*
160 * Avoid calls to __switch_to_xtra() on UP as STIBP is not evaluated.
161 */
162 #ifdef CONFIG_SMP
163 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE | _TIF_SPEC_IB)
164 #else
165 # define _TIF_WORK_CTXSW (_TIF_WORK_CTXSW_BASE)
166 #endif
167
168 #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY)
169 #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW)
170
171 #define STACK_WARN (THREAD_SIZE/8)
172
173 /*
174 * macros/functions for gaining access to the thread information structure
175 *
176 * preempt_count needs to be 1 initially, until the scheduler is functional.
177 */
178 #ifndef __ASSEMBLY__
179
current_thread_info(void)180 static inline struct thread_info *current_thread_info(void)
181 {
182 return (struct thread_info *)(current_top_of_stack() - THREAD_SIZE);
183 }
184
185 /*
186 * Walks up the stack frames to make sure that the specified object is
187 * entirely contained by a single stack frame.
188 *
189 * Returns:
190 * 1 if within a frame
191 * -1 if placed across a frame boundary (or outside stack)
192 * 0 unable to determine (no frame pointers, etc)
193 */
arch_within_stack_frames(const void * const stack,const void * const stackend,const void * obj,unsigned long len)194 static inline int arch_within_stack_frames(const void * const stack,
195 const void * const stackend,
196 const void *obj, unsigned long len)
197 {
198 #if defined(CONFIG_FRAME_POINTER)
199 const void *frame = NULL;
200 const void *oldframe;
201
202 oldframe = __builtin_frame_address(1);
203 if (oldframe)
204 frame = __builtin_frame_address(2);
205 /*
206 * low ----------------------------------------------> high
207 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
208 * ^----------------^
209 * allow copies only within here
210 */
211 while (stack <= frame && frame < stackend) {
212 /*
213 * If obj + len extends past the last frame, this
214 * check won't pass and the next frame will be 0,
215 * causing us to bail out and correctly report
216 * the copy as invalid.
217 */
218 if (obj + len <= frame)
219 return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
220 oldframe = frame;
221 frame = *(const void * const *)frame;
222 }
223 return -1;
224 #else
225 return 0;
226 #endif
227 }
228
229 #else /* !__ASSEMBLY__ */
230
231 #ifdef CONFIG_X86_64
232 # define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
233 #endif
234
235 /* Load thread_info address into "reg" */
236 #define GET_THREAD_INFO(reg) \
237 _ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \
238 _ASM_SUB $(THREAD_SIZE),reg ;
239
240 /*
241 * ASM operand which evaluates to a 'thread_info' address of
242 * the current task, if it is known that "reg" is exactly "off"
243 * bytes below the top of the stack currently.
244 *
245 * ( The kernel stack's size is known at build time, it is usually
246 * 2 or 4 pages, and the bottom of the kernel stack contains
247 * the thread_info structure. So to access the thread_info very
248 * quickly from assembly code we can calculate down from the
249 * top of the kernel stack to the bottom, using constant,
250 * build-time calculations only. )
251 *
252 * For example, to fetch the current thread_info->flags value into %eax
253 * on x86-64 defconfig kernels, in syscall entry code where RSP is
254 * currently at exactly SIZEOF_PTREGS bytes away from the top of the
255 * stack:
256 *
257 * mov ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS), %eax
258 *
259 * will translate to:
260 *
261 * 8b 84 24 b8 c0 ff ff mov -0x3f48(%rsp), %eax
262 *
263 * which is below the current RSP by almost 16K.
264 */
265 #define ASM_THREAD_INFO(field, reg, off) ((field)+(off)-THREAD_SIZE)(reg)
266
267 #endif
268
269 /*
270 * Thread-synchronous status.
271 *
272 * This is different from the flags in that nobody else
273 * ever touches our thread-synchronous status, so we don't
274 * have to worry about atomic accesses.
275 */
276 #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
277 #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
278
279 #ifndef __ASSEMBLY__
280 #define HAVE_SET_RESTORE_SIGMASK 1
set_restore_sigmask(void)281 static inline void set_restore_sigmask(void)
282 {
283 struct thread_info *ti = current_thread_info();
284 ti->status |= TS_RESTORE_SIGMASK;
285 WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
286 }
clear_restore_sigmask(void)287 static inline void clear_restore_sigmask(void)
288 {
289 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
290 }
test_restore_sigmask(void)291 static inline bool test_restore_sigmask(void)
292 {
293 return current_thread_info()->status & TS_RESTORE_SIGMASK;
294 }
test_and_clear_restore_sigmask(void)295 static inline bool test_and_clear_restore_sigmask(void)
296 {
297 struct thread_info *ti = current_thread_info();
298 if (!(ti->status & TS_RESTORE_SIGMASK))
299 return false;
300 ti->status &= ~TS_RESTORE_SIGMASK;
301 return true;
302 }
303
is_ia32_task(void)304 static inline bool is_ia32_task(void)
305 {
306 #ifdef CONFIG_X86_32
307 return true;
308 #endif
309 #ifdef CONFIG_IA32_EMULATION
310 if (current_thread_info()->status & TS_COMPAT)
311 return true;
312 #endif
313 return false;
314 }
315
316 /*
317 * Force syscall return via IRET by making it look as if there was
318 * some work pending. IRET is our most capable (but slowest) syscall
319 * return path, which is able to restore modified SS, CS and certain
320 * EFLAGS values that other (fast) syscall return instructions
321 * are not able to restore properly.
322 */
323 #define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
324
325 #endif /* !__ASSEMBLY__ */
326
327 #ifndef __ASSEMBLY__
328 extern void arch_task_cache_init(void);
329 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
330 extern void arch_release_task_struct(struct task_struct *tsk);
331 #endif
332 #endif /* _ASM_X86_THREAD_INFO_H */
333