1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_ENTRYCOMMON_H
3 #define __LINUX_ENTRYCOMMON_H
5 #include <linux/tracehook.h>
6 #include <linux/syscalls.h>
7 #include <linux/seccomp.h>
8 #include <linux/sched.h>
10 #include <asm/entry-common.h>
13 * Define dummy _TIF work flags if not defined by the architecture or for
14 * disabled functionality.
16 #ifndef _TIF_PATCH_PENDING
17 # define _TIF_PATCH_PENDING (0)
21 # define _TIF_UPROBE (0)
25 * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
27 #ifndef ARCH_SYSCALL_WORK_ENTER
28 # define ARCH_SYSCALL_WORK_ENTER (0)
32 * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
34 #ifndef ARCH_SYSCALL_WORK_EXIT
35 # define ARCH_SYSCALL_WORK_EXIT (0)
38 #define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
39 SYSCALL_WORK_SYSCALL_TRACEPOINT | \
40 SYSCALL_WORK_SYSCALL_TRACE | \
41 SYSCALL_WORK_SYSCALL_EMU | \
42 SYSCALL_WORK_SYSCALL_AUDIT | \
43 SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
44 ARCH_SYSCALL_WORK_ENTER)
45 #define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
46 SYSCALL_WORK_SYSCALL_TRACE | \
47 SYSCALL_WORK_SYSCALL_AUDIT | \
48 SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
49 ARCH_SYSCALL_WORK_EXIT)
52 * TIF flags handled in exit_to_user_mode_loop()
54 #ifndef ARCH_EXIT_TO_USER_MODE_WORK
55 # define ARCH_EXIT_TO_USER_MODE_WORK (0)
58 #define EXIT_TO_USER_MODE_WORK \
59 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
60 _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \
61 ARCH_EXIT_TO_USER_MODE_WORK)
64 * arch_check_user_regs - Architecture specific sanity check for user mode regs
65 * @regs: Pointer to currents pt_regs
67 * Defaults to an empty implementation. Can be replaced by architecture
70 * Invoked from syscall_enter_from_user_mode() in the non-instrumentable
71 * section. Use __always_inline so the compiler cannot push it out of line
72 * and make it instrumentable.
74 static __always_inline void arch_check_user_regs(struct pt_regs *regs);
76 #ifndef arch_check_user_regs
77 static __always_inline void arch_check_user_regs(struct pt_regs *regs) {}
81 * arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry()
82 * @regs: Pointer to currents pt_regs
84 * Returns: 0 on success or an error code to skip the syscall.
86 * Defaults to tracehook_report_syscall_entry(). Can be replaced by
87 * architecture specific code.
89 * Invoked from syscall_enter_from_user_mode()
91 static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs);
93 #ifndef arch_syscall_enter_tracehook
94 static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs)
96 return tracehook_report_syscall_entry(regs);
101 * enter_from_user_mode - Establish state when coming from user mode
103 * Syscall/interrupt entry disables interrupts, but user mode is traced as
104 * interrupts enabled. Also with NO_HZ_FULL RCU might be idle.
106 * 1) Tell lockdep that interrupts are disabled
107 * 2) Invoke context tracking if enabled to reactivate RCU
108 * 3) Trace interrupts off state
110 * Invoked from architecture specific syscall entry code with interrupts
111 * disabled. The calling code has to be non-instrumentable. When the
112 * function returns all state is correct and interrupts are still
113 * disabled. The subsequent functions can be instrumented.
115 * This is invoked when there is architecture specific functionality to be
116 * done between establishing state and enabling interrupts. The caller must
117 * enable interrupts before invoking syscall_enter_from_user_mode_work().
119 void enter_from_user_mode(struct pt_regs *regs);
122 * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
123 * @regs: Pointer to currents pt_regs
125 * Invoked from architecture specific syscall entry code with interrupts
126 * disabled. The calling code has to be non-instrumentable. When the
127 * function returns all state is correct, interrupts are enabled and the
128 * subsequent functions can be instrumented.
130 * This handles lockdep, RCU (context tracking) and tracing state, i.e.
131 * the functionality provided by enter_from_user_mode().
133 * This is invoked when there is extra architecture specific functionality
134 * to be done between establishing state and handling user mode entry work.
136 void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
139 * syscall_enter_from_user_mode_work - Check and handle work before invoking
141 * @regs: Pointer to currents pt_regs
142 * @syscall: The syscall number
144 * Invoked from architecture specific syscall entry code with interrupts
145 * enabled after invoking syscall_enter_from_user_mode_prepare() and extra
146 * architecture specific work.
148 * Returns: The original or a modified syscall number
150 * If the returned syscall number is -1 then the syscall should be
151 * skipped. In this case the caller may invoke syscall_set_error() or
152 * syscall_set_return_value() first. If neither of those are called and -1
153 * is returned, then the syscall will fail with ENOSYS.
155 * It handles the following work items:
157 * 1) syscall_work flag dependent invocations of
158 * arch_syscall_enter_tracehook(), __secure_computing(), trace_sys_enter()
159 * 2) Invocation of audit_syscall_entry()
161 long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
164 * syscall_enter_from_user_mode - Establish state and check and handle work
165 * before invoking a syscall
166 * @regs: Pointer to currents pt_regs
167 * @syscall: The syscall number
169 * Invoked from architecture specific syscall entry code with interrupts
170 * disabled. The calling code has to be non-instrumentable. When the
171 * function returns all state is correct, interrupts are enabled and the
172 * subsequent functions can be instrumented.
174 * This is combination of syscall_enter_from_user_mode_prepare() and
175 * syscall_enter_from_user_mode_work().
177 * Returns: The original or a modified syscall number. See
178 * syscall_enter_from_user_mode_work() for further explanation.
180 long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
183 * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
184 * @ti_work: Cached TIF flags gathered with interrupts disabled
186 * Defaults to local_irq_enable(). Can be supplied by architecture specific
189 static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
191 #ifndef local_irq_enable_exit_to_user
192 static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
199 * local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
201 * Defaults to local_irq_disable(). Can be supplied by architecture specific
204 static inline void local_irq_disable_exit_to_user(void);
206 #ifndef local_irq_disable_exit_to_user
207 static inline void local_irq_disable_exit_to_user(void)
214 * arch_exit_to_user_mode_work - Architecture specific TIF work for exit
216 * @regs: Pointer to currents pt_regs
217 * @ti_work: Cached TIF flags gathered with interrupts disabled
219 * Invoked from exit_to_user_mode_loop() with interrupt enabled
221 * Defaults to NOOP. Can be supplied by architecture specific code.
223 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
224 unsigned long ti_work);
226 #ifndef arch_exit_to_user_mode_work
227 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
228 unsigned long ti_work)
234 * arch_exit_to_user_mode_prepare - Architecture specific preparation for
236 * @regs: Pointer to currents pt_regs
237 * @ti_work: Cached TIF flags gathered with interrupts disabled
239 * Invoked from exit_to_user_mode_prepare() with interrupt disabled as the last
240 * function before return. Defaults to NOOP.
242 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
243 unsigned long ti_work);
245 #ifndef arch_exit_to_user_mode_prepare
246 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
247 unsigned long ti_work)
253 * arch_exit_to_user_mode - Architecture specific final work before
256 * Invoked from exit_to_user_mode() with interrupt disabled as the last
257 * function before return. Defaults to NOOP.
259 * This needs to be __always_inline because it is non-instrumentable code
260 * invoked after context tracking switched to user mode.
262 * An architecture implementation must not do anything complex, no locking
263 * etc. The main purpose is for speculation mitigations.
265 static __always_inline void arch_exit_to_user_mode(void);
267 #ifndef arch_exit_to_user_mode
268 static __always_inline void arch_exit_to_user_mode(void) { }
272 * arch_do_signal_or_restart - Architecture specific signal delivery function
273 * @regs: Pointer to currents pt_regs
274 * @has_signal: actual signal to handle
276 * Invoked from exit_to_user_mode_loop().
278 void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal);
281 * arch_syscall_exit_tracehook - Wrapper around tracehook_report_syscall_exit()
282 * @regs: Pointer to currents pt_regs
283 * @step: Indicator for single step
285 * Defaults to tracehook_report_syscall_exit(). Can be replaced by
286 * architecture specific code.
288 * Invoked from syscall_exit_to_user_mode()
290 static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step);
292 #ifndef arch_syscall_exit_tracehook
293 static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step)
295 tracehook_report_syscall_exit(regs, step);
300 * exit_to_user_mode - Fixup state when exiting to user mode
302 * Syscall/interrupt exit enables interrupts, but the kernel state is
303 * interrupts disabled when this is invoked. Also tell RCU about it.
305 * 1) Trace interrupts on state
306 * 2) Invoke context tracking if enabled to adjust RCU state
307 * 3) Invoke architecture specific last minute exit code, e.g. speculation
308 * mitigations, etc.: arch_exit_to_user_mode()
309 * 4) Tell lockdep that interrupts are enabled
311 * Invoked from architecture specific code when syscall_exit_to_user_mode()
312 * is not suitable as the last step before returning to userspace. Must be
313 * invoked with interrupts disabled and the caller must be
314 * non-instrumentable.
315 * The caller has to invoke syscall_exit_to_user_mode_work() before this.
317 void exit_to_user_mode(void);
320 * syscall_exit_to_user_mode_work - Handle work before returning to user mode
321 * @regs: Pointer to currents pt_regs
323 * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
324 * exit_to_user_mode() to perform the final transition to user mode.
326 * Calling convention is the same as for syscall_exit_to_user_mode() and it
327 * returns with all work handled and interrupts disabled. The caller must
328 * invoke exit_to_user_mode() before actually switching to user mode to
329 * make the final state transitions. Interrupts must stay disabled between
330 * return from this function and the invocation of exit_to_user_mode().
332 void syscall_exit_to_user_mode_work(struct pt_regs *regs);
335 * syscall_exit_to_user_mode - Handle work before returning to user mode
336 * @regs: Pointer to currents pt_regs
338 * Invoked with interrupts enabled and fully valid regs. Returns with all
339 * work handled, interrupts disabled such that the caller can immediately
340 * switch to user mode. Called from architecture specific syscall and ret
344 * 1) One-time syscall exit work:
345 * - rseq syscall exit
348 * - tracehook (single stepping)
350 * 2) Preparatory work
351 * - Exit to user mode loop (common TIF handling). Invokes
352 * arch_exit_to_user_mode_work() for architecture specific TIF work
353 * - Architecture specific one time work arch_exit_to_user_mode_prepare()
354 * - Address limit and lockdep checks
356 * 3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the
357 * functionality in exit_to_user_mode().
359 * This is a combination of syscall_exit_to_user_mode_work() (1,2) and
360 * exit_to_user_mode(). This function is preferred unless there is a
361 * compelling architectural reason to use the seperate functions.
363 void syscall_exit_to_user_mode(struct pt_regs *regs);
366 * irqentry_enter_from_user_mode - Establish state before invoking the irq handler
367 * @regs: Pointer to currents pt_regs
369 * Invoked from architecture specific entry code with interrupts disabled.
370 * Can only be called when the interrupt entry came from user mode. The
371 * calling code must be non-instrumentable. When the function returns all
372 * state is correct and the subsequent functions can be instrumented.
374 * The function establishes state (lockdep, RCU (context tracking), tracing)
376 void irqentry_enter_from_user_mode(struct pt_regs *regs);
379 * irqentry_exit_to_user_mode - Interrupt exit work
380 * @regs: Pointer to current's pt_regs
382 * Invoked with interrupts disbled and fully valid regs. Returns with all
383 * work handled, interrupts disabled such that the caller can immediately
384 * switch to user mode. Called from architecture specific interrupt
387 * The call order is #2 and #3 as described in syscall_exit_to_user_mode().
388 * Interrupt exit is not invoking #1 which is the syscall specific one time
391 void irqentry_exit_to_user_mode(struct pt_regs *regs);
393 #ifndef irqentry_state
395 * struct irqentry_state - Opaque object for exception state storage
396 * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
397 * exit path has to invoke rcu_irq_exit().
398 * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
399 * lockdep state is restored correctly on exit from nmi.
401 * This opaque object is filled in by the irqentry_*_enter() functions and
402 * must be passed back into the corresponding irqentry_*_exit() functions
403 * when the exception is complete.
405 * Callers of irqentry_*_[enter|exit]() must consider this structure opaque
406 * and all members private. Descriptions of the members are provided to aid in
407 * the maintenance of the irqentry_*() functions.
409 typedef struct irqentry_state {
418 * irqentry_enter - Handle state tracking on ordinary interrupt entries
419 * @regs: Pointer to pt_regs of interrupted context
422 * - lockdep irqflag state tracking as low level ASM entry disabled
425 * - Context tracking if the exception hit user mode.
427 * - The hardirq tracer to keep the state consistent as low level ASM
428 * entry disabled interrupts.
430 * As a precondition, this requires that the entry came from user mode,
431 * idle, or a kernel context in which RCU is watching.
433 * For kernel mode entries RCU handling is done conditional. If RCU is
434 * watching then the only RCU requirement is to check whether the tick has
435 * to be restarted. If RCU is not watching then rcu_irq_enter() has to be
436 * invoked on entry and rcu_irq_exit() on exit.
438 * Avoiding the rcu_irq_enter/exit() calls is an optimization but also
439 * solves the problem of kernel mode pagefaults which can schedule, which
440 * is not possible after invoking rcu_irq_enter() without undoing it.
442 * For user mode entries irqentry_enter_from_user_mode() is invoked to
443 * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
444 * would not be possible.
446 * Returns: An opaque object that must be passed to idtentry_exit()
448 irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
451 * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
453 * Conditional reschedule with additional sanity checks.
455 void irqentry_exit_cond_resched(void);
458 * irqentry_exit - Handle return from exception that used irqentry_enter()
459 * @regs: Pointer to pt_regs (exception entry regs)
460 * @state: Return value from matching call to irqentry_enter()
462 * Depending on the return target (kernel/user) this runs the necessary
463 * preemption and work checks if possible and required and returns to
464 * the caller with interrupts disabled and no further work pending.
466 * This is the last action before returning to the low level ASM code which
467 * just needs to return to the appropriate context.
469 * Counterpart to irqentry_enter().
471 void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
474 * irqentry_nmi_enter - Handle NMI entry
475 * @regs: Pointer to currents pt_regs
477 * Similar to irqentry_enter() but taking care of the NMI constraints.
479 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
482 * irqentry_nmi_exit - Handle return from NMI handling
483 * @regs: Pointer to pt_regs (NMI entry regs)
484 * @irq_state: Return value from matching call to irqentry_nmi_enter()
486 * Last action before returning to the low level assembly code.
488 * Counterpart to irqentry_nmi_enter().
490 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);