1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_ENTRYCOMMON_H 2 #ifndef __LINUX_ENTRYCOMMON_H
3 #define __LINUX_ENTRYCOMMON_H 3 #define __LINUX_ENTRYCOMMON_H
4 4
5 #include <linux/static_call_types.h> 5 #include <linux/static_call_types.h>
6 #include <linux/ptrace.h> 6 #include <linux/ptrace.h>
7 #include <linux/syscalls.h> 7 #include <linux/syscalls.h>
8 #include <linux/seccomp.h> 8 #include <linux/seccomp.h>
9 #include <linux/sched.h> 9 #include <linux/sched.h>
10 #include <linux/context_tracking.h> 10 #include <linux/context_tracking.h>
11 #include <linux/livepatch.h> 11 #include <linux/livepatch.h>
12 #include <linux/resume_user_mode.h> 12 #include <linux/resume_user_mode.h>
13 #include <linux/tick.h> 13 #include <linux/tick.h>
14 #include <linux/kmsan.h> 14 #include <linux/kmsan.h>
15 15
16 #include <asm/entry-common.h> 16 #include <asm/entry-common.h>
17 17
18 /* 18 /*
19 * Define dummy _TIF work flags if not defined 19 * Define dummy _TIF work flags if not defined by the architecture or for
20 * disabled functionality. 20 * disabled functionality.
21 */ 21 */
22 #ifndef _TIF_PATCH_PENDING 22 #ifndef _TIF_PATCH_PENDING
23 # define _TIF_PATCH_PENDING (0) 23 # define _TIF_PATCH_PENDING (0)
24 #endif 24 #endif
25 25
26 #ifndef _TIF_UPROBE 26 #ifndef _TIF_UPROBE
27 # define _TIF_UPROBE (0) 27 # define _TIF_UPROBE (0)
28 #endif 28 #endif
29 29
30 /* 30 /*
31 * SYSCALL_WORK flags handled in syscall_enter 31 * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
32 */ 32 */
33 #ifndef ARCH_SYSCALL_WORK_ENTER 33 #ifndef ARCH_SYSCALL_WORK_ENTER
34 # define ARCH_SYSCALL_WORK_ENTER (0) 34 # define ARCH_SYSCALL_WORK_ENTER (0)
35 #endif 35 #endif
36 36
37 /* 37 /*
38 * SYSCALL_WORK flags handled in syscall_exit_ 38 * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
39 */ 39 */
40 #ifndef ARCH_SYSCALL_WORK_EXIT 40 #ifndef ARCH_SYSCALL_WORK_EXIT
41 # define ARCH_SYSCALL_WORK_EXIT (0) 41 # define ARCH_SYSCALL_WORK_EXIT (0)
42 #endif 42 #endif
43 43
44 #define SYSCALL_WORK_ENTER (SYSCALL_WORK_ 44 #define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
45 SYSCALL_WORK_ 45 SYSCALL_WORK_SYSCALL_TRACEPOINT | \
46 SYSCALL_WORK_ 46 SYSCALL_WORK_SYSCALL_TRACE | \
47 SYSCALL_WORK_ 47 SYSCALL_WORK_SYSCALL_EMU | \
48 SYSCALL_WORK_ 48 SYSCALL_WORK_SYSCALL_AUDIT | \
49 SYSCALL_WORK_ 49 SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
50 ARCH_SYSCALL_ 50 ARCH_SYSCALL_WORK_ENTER)
51 #define SYSCALL_WORK_EXIT (SYSCALL_WORK_ 51 #define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
52 SYSCALL_WORK_ 52 SYSCALL_WORK_SYSCALL_TRACE | \
53 SYSCALL_WORK_ 53 SYSCALL_WORK_SYSCALL_AUDIT | \
54 SYSCALL_WORK_ 54 SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
55 SYSCALL_WORK_ 55 SYSCALL_WORK_SYSCALL_EXIT_TRAP | \
56 ARCH_SYSCALL_ 56 ARCH_SYSCALL_WORK_EXIT)
57 57
58 /* 58 /*
59 * TIF flags handled in exit_to_user_mode_loop 59 * TIF flags handled in exit_to_user_mode_loop()
60 */ 60 */
61 #ifndef ARCH_EXIT_TO_USER_MODE_WORK 61 #ifndef ARCH_EXIT_TO_USER_MODE_WORK
62 # define ARCH_EXIT_TO_USER_MODE_WORK 62 # define ARCH_EXIT_TO_USER_MODE_WORK (0)
63 #endif 63 #endif
64 64
65 #define EXIT_TO_USER_MODE_WORK 65 #define EXIT_TO_USER_MODE_WORK \
66 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME 66 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
67 _TIF_NEED_RESCHED | _TIF_PATCH_PENDIN 67 _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \
68 ARCH_EXIT_TO_USER_MODE_WORK) 68 ARCH_EXIT_TO_USER_MODE_WORK)
69 69
70 /** 70 /**
71 * arch_enter_from_user_mode - Architecture sp 71 * arch_enter_from_user_mode - Architecture specific sanity check for user mode regs
72 * @regs: Pointer to currents pt_regs 72 * @regs: Pointer to currents pt_regs
73 * 73 *
74 * Defaults to an empty implementation. Can be 74 * Defaults to an empty implementation. Can be replaced by architecture
75 * specific code. 75 * specific code.
76 * 76 *
77 * Invoked from syscall_enter_from_user_mode() 77 * Invoked from syscall_enter_from_user_mode() in the non-instrumentable
78 * section. Use __always_inline so the compile 78 * section. Use __always_inline so the compiler cannot push it out of line
79 * and make it instrumentable. 79 * and make it instrumentable.
80 */ 80 */
81 static __always_inline void arch_enter_from_us 81 static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs);
82 82
83 #ifndef arch_enter_from_user_mode 83 #ifndef arch_enter_from_user_mode
84 static __always_inline void arch_enter_from_us 84 static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {}
85 #endif 85 #endif
86 86
87 /** 87 /**
88 * enter_from_user_mode - Establish state when 88 * enter_from_user_mode - Establish state when coming from user mode
89 * 89 *
90 * Syscall/interrupt entry disables interrupts 90 * Syscall/interrupt entry disables interrupts, but user mode is traced as
91 * interrupts enabled. Also with NO_HZ_FULL RC 91 * interrupts enabled. Also with NO_HZ_FULL RCU might be idle.
92 * 92 *
93 * 1) Tell lockdep that interrupts are disable 93 * 1) Tell lockdep that interrupts are disabled
94 * 2) Invoke context tracking if enabled to re 94 * 2) Invoke context tracking if enabled to reactivate RCU
95 * 3) Trace interrupts off state 95 * 3) Trace interrupts off state
96 * 96 *
97 * Invoked from architecture specific syscall 97 * Invoked from architecture specific syscall entry code with interrupts
98 * disabled. The calling code has to be non-in 98 * disabled. The calling code has to be non-instrumentable. When the
99 * function returns all state is correct and i 99 * function returns all state is correct and interrupts are still
100 * disabled. The subsequent functions can be i 100 * disabled. The subsequent functions can be instrumented.
101 * 101 *
102 * This is invoked when there is architecture 102 * This is invoked when there is architecture specific functionality to be
103 * done between establishing state and enablin 103 * done between establishing state and enabling interrupts. The caller must
104 * enable interrupts before invoking syscall_e 104 * enable interrupts before invoking syscall_enter_from_user_mode_work().
105 */ 105 */
106 static __always_inline void enter_from_user_mo 106 static __always_inline void enter_from_user_mode(struct pt_regs *regs)
107 { 107 {
108 arch_enter_from_user_mode(regs); 108 arch_enter_from_user_mode(regs);
109 lockdep_hardirqs_off(CALLER_ADDR0); 109 lockdep_hardirqs_off(CALLER_ADDR0);
110 110
111 CT_WARN_ON(__ct_state() != CT_STATE_US 111 CT_WARN_ON(__ct_state() != CT_STATE_USER);
112 user_exit_irqoff(); 112 user_exit_irqoff();
113 113
114 instrumentation_begin(); 114 instrumentation_begin();
115 kmsan_unpoison_entry_regs(regs); 115 kmsan_unpoison_entry_regs(regs);
116 trace_hardirqs_off_finish(); 116 trace_hardirqs_off_finish();
117 instrumentation_end(); 117 instrumentation_end();
118 } 118 }
119 119
120 /** 120 /**
121 * syscall_enter_from_user_mode_prepare - Esta 121 * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
122 * @regs: Pointer to currents pt_regs 122 * @regs: Pointer to currents pt_regs
123 * 123 *
124 * Invoked from architecture specific syscall 124 * Invoked from architecture specific syscall entry code with interrupts
125 * disabled. The calling code has to be non-in 125 * disabled. The calling code has to be non-instrumentable. When the
126 * function returns all state is correct, inte 126 * function returns all state is correct, interrupts are enabled and the
127 * subsequent functions can be instrumented. 127 * subsequent functions can be instrumented.
128 * 128 *
129 * This handles lockdep, RCU (context tracking 129 * This handles lockdep, RCU (context tracking) and tracing state, i.e.
130 * the functionality provided by enter_from_us 130 * the functionality provided by enter_from_user_mode().
131 * 131 *
132 * This is invoked when there is extra archite 132 * This is invoked when there is extra architecture specific functionality
133 * to be done between establishing state and h 133 * to be done between establishing state and handling user mode entry work.
134 */ 134 */
135 void syscall_enter_from_user_mode_prepare(stru 135 void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
136 136
137 long syscall_trace_enter(struct pt_regs *regs, 137 long syscall_trace_enter(struct pt_regs *regs, long syscall,
138 unsigned long work); 138 unsigned long work);
139 139
140 /** 140 /**
141 * syscall_enter_from_user_mode_work - Check a 141 * syscall_enter_from_user_mode_work - Check and handle work before invoking
142 * a sysca 142 * a syscall
143 * @regs: Pointer to currents pt_regs 143 * @regs: Pointer to currents pt_regs
144 * @syscall: The syscall number 144 * @syscall: The syscall number
145 * 145 *
146 * Invoked from architecture specific syscall 146 * Invoked from architecture specific syscall entry code with interrupts
147 * enabled after invoking syscall_enter_from_u 147 * enabled after invoking syscall_enter_from_user_mode_prepare() and extra
148 * architecture specific work. 148 * architecture specific work.
149 * 149 *
150 * Returns: The original or a modified syscall 150 * Returns: The original or a modified syscall number
151 * 151 *
152 * If the returned syscall number is -1 then t 152 * If the returned syscall number is -1 then the syscall should be
153 * skipped. In this case the caller may invoke 153 * skipped. In this case the caller may invoke syscall_set_error() or
154 * syscall_set_return_value() first. If neith 154 * syscall_set_return_value() first. If neither of those are called and -1
155 * is returned, then the syscall will fail wit 155 * is returned, then the syscall will fail with ENOSYS.
156 * 156 *
157 * It handles the following work items: 157 * It handles the following work items:
158 * 158 *
159 * 1) syscall_work flag dependent invocations 159 * 1) syscall_work flag dependent invocations of
160 * ptrace_report_syscall_entry(), __secure 160 * ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter()
161 * 2) Invocation of audit_syscall_entry() 161 * 2) Invocation of audit_syscall_entry()
162 */ 162 */
163 static __always_inline long syscall_enter_from 163 static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
164 { 164 {
165 unsigned long work = READ_ONCE(current 165 unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
166 166
167 if (work & SYSCALL_WORK_ENTER) 167 if (work & SYSCALL_WORK_ENTER)
168 syscall = syscall_trace_enter( 168 syscall = syscall_trace_enter(regs, syscall, work);
169 169
170 return syscall; 170 return syscall;
171 } 171 }
172 172
173 /** 173 /**
174 * syscall_enter_from_user_mode - Establish st 174 * syscall_enter_from_user_mode - Establish state and check and handle work
175 * before invok 175 * before invoking a syscall
176 * @regs: Pointer to currents pt_regs 176 * @regs: Pointer to currents pt_regs
177 * @syscall: The syscall number 177 * @syscall: The syscall number
178 * 178 *
179 * Invoked from architecture specific syscall 179 * Invoked from architecture specific syscall entry code with interrupts
180 * disabled. The calling code has to be non-in 180 * disabled. The calling code has to be non-instrumentable. When the
181 * function returns all state is correct, inte 181 * function returns all state is correct, interrupts are enabled and the
182 * subsequent functions can be instrumented. 182 * subsequent functions can be instrumented.
183 * 183 *
184 * This is combination of syscall_enter_from_u 184 * This is combination of syscall_enter_from_user_mode_prepare() and
185 * syscall_enter_from_user_mode_work(). 185 * syscall_enter_from_user_mode_work().
186 * 186 *
187 * Returns: The original or a modified syscall 187 * Returns: The original or a modified syscall number. See
188 * syscall_enter_from_user_mode_work() for fur 188 * syscall_enter_from_user_mode_work() for further explanation.
189 */ 189 */
190 static __always_inline long syscall_enter_from 190 static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
191 { 191 {
192 long ret; 192 long ret;
193 193
194 enter_from_user_mode(regs); 194 enter_from_user_mode(regs);
195 195
196 instrumentation_begin(); 196 instrumentation_begin();
197 local_irq_enable(); 197 local_irq_enable();
198 ret = syscall_enter_from_user_mode_wor 198 ret = syscall_enter_from_user_mode_work(regs, syscall);
199 instrumentation_end(); 199 instrumentation_end();
200 200
201 return ret; 201 return ret;
202 } 202 }
203 203
204 /** 204 /**
205 * local_irq_enable_exit_to_user - Exit to use 205 * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
206 * @ti_work: Cached TIF flags gathered with 206 * @ti_work: Cached TIF flags gathered with interrupts disabled
207 * 207 *
208 * Defaults to local_irq_enable(). Can be supp 208 * Defaults to local_irq_enable(). Can be supplied by architecture specific
209 * code. 209 * code.
210 */ 210 */
211 static inline void local_irq_enable_exit_to_us 211 static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
212 212
213 #ifndef local_irq_enable_exit_to_user 213 #ifndef local_irq_enable_exit_to_user
214 static inline void local_irq_enable_exit_to_us 214 static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
215 { 215 {
216 local_irq_enable(); 216 local_irq_enable();
217 } 217 }
218 #endif 218 #endif
219 219
220 /** 220 /**
221 * local_irq_disable_exit_to_user - Exit to us 221 * local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
222 * 222 *
223 * Defaults to local_irq_disable(). Can be sup 223 * Defaults to local_irq_disable(). Can be supplied by architecture specific
224 * code. 224 * code.
225 */ 225 */
226 static inline void local_irq_disable_exit_to_u 226 static inline void local_irq_disable_exit_to_user(void);
227 227
228 #ifndef local_irq_disable_exit_to_user 228 #ifndef local_irq_disable_exit_to_user
229 static inline void local_irq_disable_exit_to_u 229 static inline void local_irq_disable_exit_to_user(void)
230 { 230 {
231 local_irq_disable(); 231 local_irq_disable();
232 } 232 }
233 #endif 233 #endif
234 234
235 /** 235 /**
236 * arch_exit_to_user_mode_work - Architecture 236 * arch_exit_to_user_mode_work - Architecture specific TIF work for exit
237 * to user mode. 237 * to user mode.
238 * @regs: Pointer to currents pt_regs 238 * @regs: Pointer to currents pt_regs
239 * @ti_work: Cached TIF flags gathered with 239 * @ti_work: Cached TIF flags gathered with interrupts disabled
240 * 240 *
241 * Invoked from exit_to_user_mode_loop() with 241 * Invoked from exit_to_user_mode_loop() with interrupt enabled
242 * 242 *
243 * Defaults to NOOP. Can be supplied by archit 243 * Defaults to NOOP. Can be supplied by architecture specific code.
244 */ 244 */
245 static inline void arch_exit_to_user_mode_work 245 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
246 246 unsigned long ti_work);
247 247
248 #ifndef arch_exit_to_user_mode_work 248 #ifndef arch_exit_to_user_mode_work
249 static inline void arch_exit_to_user_mode_work 249 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
250 250 unsigned long ti_work)
251 { 251 {
252 } 252 }
253 #endif 253 #endif
254 254
255 /** 255 /**
256 * arch_exit_to_user_mode_prepare - Architectu 256 * arch_exit_to_user_mode_prepare - Architecture specific preparation for
257 * exit to us 257 * exit to user mode.
258 * @regs: Pointer to currents pt_regs 258 * @regs: Pointer to currents pt_regs
259 * @ti_work: Cached TIF flags gathered with 259 * @ti_work: Cached TIF flags gathered with interrupts disabled
260 * 260 *
261 * Invoked from exit_to_user_mode_prepare() wi 261 * Invoked from exit_to_user_mode_prepare() with interrupt disabled as the last
262 * function before return. Defaults to NOOP. 262 * function before return. Defaults to NOOP.
263 */ 263 */
264 static inline void arch_exit_to_user_mode_prep 264 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
265 265 unsigned long ti_work);
266 266
267 #ifndef arch_exit_to_user_mode_prepare 267 #ifndef arch_exit_to_user_mode_prepare
268 static inline void arch_exit_to_user_mode_prep 268 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
269 269 unsigned long ti_work)
270 { 270 {
271 } 271 }
272 #endif 272 #endif
273 273
274 /** 274 /**
275 * arch_exit_to_user_mode - Architecture speci 275 * arch_exit_to_user_mode - Architecture specific final work before
276 * exit to user mode. 276 * exit to user mode.
277 * 277 *
278 * Invoked from exit_to_user_mode() with inter 278 * Invoked from exit_to_user_mode() with interrupt disabled as the last
279 * function before return. Defaults to NOOP. 279 * function before return. Defaults to NOOP.
280 * 280 *
281 * This needs to be __always_inline because it 281 * This needs to be __always_inline because it is non-instrumentable code
282 * invoked after context tracking switched to 282 * invoked after context tracking switched to user mode.
283 * 283 *
284 * An architecture implementation must not do 284 * An architecture implementation must not do anything complex, no locking
285 * etc. The main purpose is for speculation mi 285 * etc. The main purpose is for speculation mitigations.
286 */ 286 */
287 static __always_inline void arch_exit_to_user_ 287 static __always_inline void arch_exit_to_user_mode(void);
288 288
289 #ifndef arch_exit_to_user_mode 289 #ifndef arch_exit_to_user_mode
290 static __always_inline void arch_exit_to_user_ 290 static __always_inline void arch_exit_to_user_mode(void) { }
291 #endif 291 #endif
292 292
293 /** 293 /**
294 * arch_do_signal_or_restart - Architecture s 294 * arch_do_signal_or_restart - Architecture specific signal delivery function
295 * @regs: Pointer to currents pt_regs 295 * @regs: Pointer to currents pt_regs
296 * 296 *
297 * Invoked from exit_to_user_mode_loop(). 297 * Invoked from exit_to_user_mode_loop().
298 */ 298 */
299 void arch_do_signal_or_restart(struct pt_regs 299 void arch_do_signal_or_restart(struct pt_regs *regs);
300 300
301 /** 301 /**
302 * exit_to_user_mode_loop - do any pending wor 302 * exit_to_user_mode_loop - do any pending work before leaving to user space
303 */ 303 */
304 unsigned long exit_to_user_mode_loop(struct pt 304 unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
305 unsigned 305 unsigned long ti_work);
306 306
307 /** 307 /**
308 * exit_to_user_mode_prepare - call exit_to_us 308 * exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required
309 * @regs: Pointer to pt_regs on entry st 309 * @regs: Pointer to pt_regs on entry stack
310 * 310 *
311 * 1) check that interrupts are disabled 311 * 1) check that interrupts are disabled
312 * 2) call tick_nohz_user_enter_prepare() 312 * 2) call tick_nohz_user_enter_prepare()
313 * 3) call exit_to_user_mode_loop() if any fla 313 * 3) call exit_to_user_mode_loop() if any flags from
314 * EXIT_TO_USER_MODE_WORK are set 314 * EXIT_TO_USER_MODE_WORK are set
315 * 4) check that interrupts are still disabled 315 * 4) check that interrupts are still disabled
316 */ 316 */
317 static __always_inline void exit_to_user_mode_ 317 static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs)
318 { 318 {
319 unsigned long ti_work; 319 unsigned long ti_work;
320 320
321 lockdep_assert_irqs_disabled(); 321 lockdep_assert_irqs_disabled();
322 322
323 /* Flush pending rcuog wakeup before t 323 /* Flush pending rcuog wakeup before the last need_resched() check */
324 tick_nohz_user_enter_prepare(); 324 tick_nohz_user_enter_prepare();
325 325
326 ti_work = read_thread_flags(); 326 ti_work = read_thread_flags();
327 if (unlikely(ti_work & EXIT_TO_USER_MO 327 if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
328 ti_work = exit_to_user_mode_lo 328 ti_work = exit_to_user_mode_loop(regs, ti_work);
329 329
330 arch_exit_to_user_mode_prepare(regs, t 330 arch_exit_to_user_mode_prepare(regs, ti_work);
331 331
332 /* Ensure that kernel state is sane fo 332 /* Ensure that kernel state is sane for a return to userspace */
333 kmap_assert_nomap(); 333 kmap_assert_nomap();
334 lockdep_assert_irqs_disabled(); 334 lockdep_assert_irqs_disabled();
335 lockdep_sys_exit(); 335 lockdep_sys_exit();
336 } 336 }
337 337
338 /** 338 /**
339 * exit_to_user_mode - Fixup state when exitin 339 * exit_to_user_mode - Fixup state when exiting to user mode
340 * 340 *
341 * Syscall/interrupt exit enables interrupts, 341 * Syscall/interrupt exit enables interrupts, but the kernel state is
342 * interrupts disabled when this is invoked. A 342 * interrupts disabled when this is invoked. Also tell RCU about it.
343 * 343 *
344 * 1) Trace interrupts on state 344 * 1) Trace interrupts on state
345 * 2) Invoke context tracking if enabled to ad 345 * 2) Invoke context tracking if enabled to adjust RCU state
346 * 3) Invoke architecture specific last minute 346 * 3) Invoke architecture specific last minute exit code, e.g. speculation
347 * mitigations, etc.: arch_exit_to_user_mod 347 * mitigations, etc.: arch_exit_to_user_mode()
348 * 4) Tell lockdep that interrupts are enabled 348 * 4) Tell lockdep that interrupts are enabled
349 * 349 *
350 * Invoked from architecture specific code whe 350 * Invoked from architecture specific code when syscall_exit_to_user_mode()
351 * is not suitable as the last step before ret 351 * is not suitable as the last step before returning to userspace. Must be
352 * invoked with interrupts disabled and the ca 352 * invoked with interrupts disabled and the caller must be
353 * non-instrumentable. 353 * non-instrumentable.
354 * The caller has to invoke syscall_exit_to_us 354 * The caller has to invoke syscall_exit_to_user_mode_work() before this.
355 */ 355 */
356 static __always_inline void exit_to_user_mode( 356 static __always_inline void exit_to_user_mode(void)
357 { 357 {
358 instrumentation_begin(); 358 instrumentation_begin();
359 trace_hardirqs_on_prepare(); 359 trace_hardirqs_on_prepare();
360 lockdep_hardirqs_on_prepare(); 360 lockdep_hardirqs_on_prepare();
361 instrumentation_end(); 361 instrumentation_end();
362 362
363 user_enter_irqoff(); 363 user_enter_irqoff();
364 arch_exit_to_user_mode(); 364 arch_exit_to_user_mode();
365 lockdep_hardirqs_on(CALLER_ADDR0); 365 lockdep_hardirqs_on(CALLER_ADDR0);
366 } 366 }
367 367
368 /** 368 /**
369 * syscall_exit_to_user_mode_work - Handle wor 369 * syscall_exit_to_user_mode_work - Handle work before returning to user mode
370 * @regs: Pointer to currents pt_regs 370 * @regs: Pointer to currents pt_regs
371 * 371 *
372 * Same as step 1 and 2 of syscall_exit_to_use 372 * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
373 * exit_to_user_mode() to perform the final tr 373 * exit_to_user_mode() to perform the final transition to user mode.
374 * 374 *
375 * Calling convention is the same as for sysca 375 * Calling convention is the same as for syscall_exit_to_user_mode() and it
376 * returns with all work handled and interrupt 376 * returns with all work handled and interrupts disabled. The caller must
377 * invoke exit_to_user_mode() before actually 377 * invoke exit_to_user_mode() before actually switching to user mode to
378 * make the final state transitions. Interrupt 378 * make the final state transitions. Interrupts must stay disabled between
379 * return from this function and the invocatio 379 * return from this function and the invocation of exit_to_user_mode().
380 */ 380 */
381 void syscall_exit_to_user_mode_work(struct pt_ 381 void syscall_exit_to_user_mode_work(struct pt_regs *regs);
382 382
383 /** 383 /**
384 * syscall_exit_to_user_mode - Handle work bef 384 * syscall_exit_to_user_mode - Handle work before returning to user mode
385 * @regs: Pointer to currents pt_regs 385 * @regs: Pointer to currents pt_regs
386 * 386 *
387 * Invoked with interrupts enabled and fully v 387 * Invoked with interrupts enabled and fully valid regs. Returns with all
388 * work handled, interrupts disabled such that 388 * work handled, interrupts disabled such that the caller can immediately
389 * switch to user mode. Called from architectu 389 * switch to user mode. Called from architecture specific syscall and ret
390 * from fork code. 390 * from fork code.
391 * 391 *
392 * The call order is: 392 * The call order is:
393 * 1) One-time syscall exit work: 393 * 1) One-time syscall exit work:
394 * - rseq syscall exit 394 * - rseq syscall exit
395 * - audit 395 * - audit
396 * - syscall tracing 396 * - syscall tracing
397 * - ptrace (single stepping) 397 * - ptrace (single stepping)
398 * 398 *
399 * 2) Preparatory work 399 * 2) Preparatory work
400 * - Exit to user mode loop (common TIF h 400 * - Exit to user mode loop (common TIF handling). Invokes
401 * arch_exit_to_user_mode_work() for ar 401 * arch_exit_to_user_mode_work() for architecture specific TIF work
402 * - Architecture specific one time work 402 * - Architecture specific one time work arch_exit_to_user_mode_prepare()
403 * - Address limit and lockdep checks 403 * - Address limit and lockdep checks
404 * 404 *
405 * 3) Final transition (lockdep, tracing, con 405 * 3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the
406 * functionality in exit_to_user_mode(). 406 * functionality in exit_to_user_mode().
407 * 407 *
408 * This is a combination of syscall_exit_to_us 408 * This is a combination of syscall_exit_to_user_mode_work() (1,2) and
409 * exit_to_user_mode(). This function is prefe 409 * exit_to_user_mode(). This function is preferred unless there is a
410 * compelling architectural reason to use the 410 * compelling architectural reason to use the separate functions.
411 */ 411 */
412 void syscall_exit_to_user_mode(struct pt_regs 412 void syscall_exit_to_user_mode(struct pt_regs *regs);
413 413
414 /** 414 /**
415 * irqentry_enter_from_user_mode - Establish s 415 * irqentry_enter_from_user_mode - Establish state before invoking the irq handler
416 * @regs: Pointer to currents pt_regs 416 * @regs: Pointer to currents pt_regs
417 * 417 *
418 * Invoked from architecture specific entry co 418 * Invoked from architecture specific entry code with interrupts disabled.
419 * Can only be called when the interrupt entry 419 * Can only be called when the interrupt entry came from user mode. The
420 * calling code must be non-instrumentable. W 420 * calling code must be non-instrumentable. When the function returns all
421 * state is correct and the subsequent functio 421 * state is correct and the subsequent functions can be instrumented.
422 * 422 *
423 * The function establishes state (lockdep, RC 423 * The function establishes state (lockdep, RCU (context tracking), tracing)
424 */ 424 */
425 void irqentry_enter_from_user_mode(struct pt_r 425 void irqentry_enter_from_user_mode(struct pt_regs *regs);
426 426
427 /** 427 /**
428 * irqentry_exit_to_user_mode - Interrupt exit 428 * irqentry_exit_to_user_mode - Interrupt exit work
429 * @regs: Pointer to current's pt_regs 429 * @regs: Pointer to current's pt_regs
430 * 430 *
431 * Invoked with interrupts disabled and fully 431 * Invoked with interrupts disabled and fully valid regs. Returns with all
432 * work handled, interrupts disabled such that 432 * work handled, interrupts disabled such that the caller can immediately
433 * switch to user mode. Called from architectu 433 * switch to user mode. Called from architecture specific interrupt
434 * handling code. 434 * handling code.
435 * 435 *
436 * The call order is #2 and #3 as described in 436 * The call order is #2 and #3 as described in syscall_exit_to_user_mode().
437 * Interrupt exit is not invoking #1 which is 437 * Interrupt exit is not invoking #1 which is the syscall specific one time
438 * work. 438 * work.
439 */ 439 */
440 void irqentry_exit_to_user_mode(struct pt_regs 440 void irqentry_exit_to_user_mode(struct pt_regs *regs);
441 441
442 #ifndef irqentry_state 442 #ifndef irqentry_state
443 /** 443 /**
444 * struct irqentry_state - Opaque object for e 444 * struct irqentry_state - Opaque object for exception state storage
445 * @exit_rcu: Used exclusively in the irqentry 445 * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
446 * exit path has to invoke ct_irq_e 446 * exit path has to invoke ct_irq_exit().
447 * @lockdep: Used exclusively in the irqentry_ 447 * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
448 * lockdep state is restored correct 448 * lockdep state is restored correctly on exit from nmi.
449 * 449 *
450 * This opaque object is filled in by the irqe 450 * This opaque object is filled in by the irqentry_*_enter() functions and
451 * must be passed back into the corresponding 451 * must be passed back into the corresponding irqentry_*_exit() functions
452 * when the exception is complete. 452 * when the exception is complete.
453 * 453 *
454 * Callers of irqentry_*_[enter|exit]() must c 454 * Callers of irqentry_*_[enter|exit]() must consider this structure opaque
455 * and all members private. Descriptions of t 455 * and all members private. Descriptions of the members are provided to aid in
456 * the maintenance of the irqentry_*() functio 456 * the maintenance of the irqentry_*() functions.
457 */ 457 */
458 typedef struct irqentry_state { 458 typedef struct irqentry_state {
459 union { 459 union {
460 bool exit_rcu; 460 bool exit_rcu;
461 bool lockdep; 461 bool lockdep;
462 }; 462 };
463 } irqentry_state_t; 463 } irqentry_state_t;
464 #endif 464 #endif
465 465
466 /** 466 /**
467 * irqentry_enter - Handle state tracking on o 467 * irqentry_enter - Handle state tracking on ordinary interrupt entries
468 * @regs: Pointer to pt_regs of interrup 468 * @regs: Pointer to pt_regs of interrupted context
469 * 469 *
470 * Invokes: 470 * Invokes:
471 * - lockdep irqflag state tracking as low le 471 * - lockdep irqflag state tracking as low level ASM entry disabled
472 * interrupts. 472 * interrupts.
473 * 473 *
474 * - Context tracking if the exception hit us 474 * - Context tracking if the exception hit user mode.
475 * 475 *
476 * - The hardirq tracer to keep the state con 476 * - The hardirq tracer to keep the state consistent as low level ASM
477 * entry disabled interrupts. 477 * entry disabled interrupts.
478 * 478 *
479 * As a precondition, this requires that the e 479 * As a precondition, this requires that the entry came from user mode,
480 * idle, or a kernel context in which RCU is w 480 * idle, or a kernel context in which RCU is watching.
481 * 481 *
482 * For kernel mode entries RCU handling is don 482 * For kernel mode entries RCU handling is done conditional. If RCU is
483 * watching then the only RCU requirement is t 483 * watching then the only RCU requirement is to check whether the tick has
484 * to be restarted. If RCU is not watching the 484 * to be restarted. If RCU is not watching then ct_irq_enter() has to be
485 * invoked on entry and ct_irq_exit() on exit. 485 * invoked on entry and ct_irq_exit() on exit.
486 * 486 *
487 * Avoiding the ct_irq_enter/exit() calls is a 487 * Avoiding the ct_irq_enter/exit() calls is an optimization but also
488 * solves the problem of kernel mode pagefault 488 * solves the problem of kernel mode pagefaults which can schedule, which
489 * is not possible after invoking ct_irq_enter 489 * is not possible after invoking ct_irq_enter() without undoing it.
490 * 490 *
491 * For user mode entries irqentry_enter_from_u 491 * For user mode entries irqentry_enter_from_user_mode() is invoked to
492 * establish the proper context for NOHZ_FULL. 492 * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
493 * would not be possible. 493 * would not be possible.
494 * 494 *
495 * Returns: An opaque object that must be pass 495 * Returns: An opaque object that must be passed to idtentry_exit()
496 */ 496 */
497 irqentry_state_t noinstr irqentry_enter(struct 497 irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
498 498
499 /** 499 /**
500 * irqentry_exit_cond_resched - Conditionally 500 * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
501 * 501 *
502 * Conditional reschedule with additional sani 502 * Conditional reschedule with additional sanity checks.
503 */ 503 */
504 void raw_irqentry_exit_cond_resched(void); 504 void raw_irqentry_exit_cond_resched(void);
505 #ifdef CONFIG_PREEMPT_DYNAMIC 505 #ifdef CONFIG_PREEMPT_DYNAMIC
506 #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) 506 #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
507 #define irqentry_exit_cond_resched_dynamic_ena 507 #define irqentry_exit_cond_resched_dynamic_enabled raw_irqentry_exit_cond_resched
508 #define irqentry_exit_cond_resched_dynamic_dis 508 #define irqentry_exit_cond_resched_dynamic_disabled NULL
509 DECLARE_STATIC_CALL(irqentry_exit_cond_resched 509 DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
510 #define irqentry_exit_cond_resched() static 510 #define irqentry_exit_cond_resched() static_call(irqentry_exit_cond_resched)()
511 #elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) 511 #elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
512 DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_ex 512 DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
513 void dynamic_irqentry_exit_cond_resched(void); 513 void dynamic_irqentry_exit_cond_resched(void);
514 #define irqentry_exit_cond_resched() dynami 514 #define irqentry_exit_cond_resched() dynamic_irqentry_exit_cond_resched()
515 #endif 515 #endif
516 #else /* CONFIG_PREEMPT_DYNAMIC */ 516 #else /* CONFIG_PREEMPT_DYNAMIC */
517 #define irqentry_exit_cond_resched() raw_ir 517 #define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched()
518 #endif /* CONFIG_PREEMPT_DYNAMIC */ 518 #endif /* CONFIG_PREEMPT_DYNAMIC */
519 519
520 /** 520 /**
521 * irqentry_exit - Handle return from exceptio 521 * irqentry_exit - Handle return from exception that used irqentry_enter()
522 * @regs: Pointer to pt_regs (exception 522 * @regs: Pointer to pt_regs (exception entry regs)
523 * @state: Return value from matching cal 523 * @state: Return value from matching call to irqentry_enter()
524 * 524 *
525 * Depending on the return target (kernel/user 525 * Depending on the return target (kernel/user) this runs the necessary
526 * preemption and work checks if possible and 526 * preemption and work checks if possible and required and returns to
527 * the caller with interrupts disabled and no 527 * the caller with interrupts disabled and no further work pending.
528 * 528 *
529 * This is the last action before returning to 529 * This is the last action before returning to the low level ASM code which
530 * just needs to return to the appropriate con 530 * just needs to return to the appropriate context.
531 * 531 *
532 * Counterpart to irqentry_enter(). 532 * Counterpart to irqentry_enter().
533 */ 533 */
534 void noinstr irqentry_exit(struct pt_regs *reg 534 void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
535 535
536 /** 536 /**
537 * irqentry_nmi_enter - Handle NMI entry 537 * irqentry_nmi_enter - Handle NMI entry
538 * @regs: Pointer to currents pt_regs 538 * @regs: Pointer to currents pt_regs
539 * 539 *
540 * Similar to irqentry_enter() but taking care 540 * Similar to irqentry_enter() but taking care of the NMI constraints.
541 */ 541 */
542 irqentry_state_t noinstr irqentry_nmi_enter(st 542 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
543 543
544 /** 544 /**
545 * irqentry_nmi_exit - Handle return from NMI 545 * irqentry_nmi_exit - Handle return from NMI handling
546 * @regs: Pointer to pt_regs (NMI entry 546 * @regs: Pointer to pt_regs (NMI entry regs)
547 * @irq_state: Return value from matching cal 547 * @irq_state: Return value from matching call to irqentry_nmi_enter()
548 * 548 *
549 * Last action before returning to the low lev 549 * Last action before returning to the low level assembly code.
550 * 550 *
551 * Counterpart to irqentry_nmi_enter(). 551 * Counterpart to irqentry_nmi_enter().
552 */ 552 */
553 void noinstr irqentry_nmi_exit(struct pt_regs 553 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);
554 554
555 #endif 555 #endif
556 556
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