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)
24 #ifndef _TIF_NOTIFY_SIGNAL
25 # define _TIF_NOTIFY_SIGNAL (0)
29 * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
31 #ifndef ARCH_SYSCALL_WORK_ENTER
32 # define ARCH_SYSCALL_WORK_ENTER (0)
36 * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
38 #ifndef ARCH_SYSCALL_WORK_EXIT
39 # define ARCH_SYSCALL_WORK_EXIT (0)
42 #define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
43 SYSCALL_WORK_SYSCALL_TRACEPOINT | \
44 SYSCALL_WORK_SYSCALL_TRACE | \
45 SYSCALL_WORK_SYSCALL_EMU | \
46 SYSCALL_WORK_SYSCALL_AUDIT | \
47 ARCH_SYSCALL_WORK_ENTER)
48 #define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
49 SYSCALL_WORK_SYSCALL_TRACE | \
50 SYSCALL_WORK_SYSCALL_AUDIT | \
51 ARCH_SYSCALL_WORK_EXIT)
54 * TIF flags handled in exit_to_user_mode_loop()
56 #ifndef ARCH_EXIT_TO_USER_MODE_WORK
57 # define ARCH_EXIT_TO_USER_MODE_WORK (0)
60 #define EXIT_TO_USER_MODE_WORK \
61 (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
62 _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \
63 ARCH_EXIT_TO_USER_MODE_WORK)
66 * arch_check_user_regs - Architecture specific sanity check for user mode regs
67 * @regs: Pointer to currents pt_regs
69 * Defaults to an empty implementation. Can be replaced by architecture
72 * Invoked from syscall_enter_from_user_mode() in the non-instrumentable
73 * section. Use __always_inline so the compiler cannot push it out of line
74 * and make it instrumentable.
76 static __always_inline void arch_check_user_regs(struct pt_regs *regs);
78 #ifndef arch_check_user_regs
79 static __always_inline void arch_check_user_regs(struct pt_regs *regs) {}
83 * arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry()
84 * @regs: Pointer to currents pt_regs
86 * Returns: 0 on success or an error code to skip the syscall.
88 * Defaults to tracehook_report_syscall_entry(). Can be replaced by
89 * architecture specific code.
91 * Invoked from syscall_enter_from_user_mode()
93 static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs);
95 #ifndef arch_syscall_enter_tracehook
96 static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs)
98 return tracehook_report_syscall_entry(regs);
103 * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
104 * @regs: Pointer to currents pt_regs
106 * Invoked from architecture specific syscall entry code with interrupts
107 * disabled. The calling code has to be non-instrumentable. When the
108 * function returns all state is correct, interrupts are enabled and the
109 * subsequent functions can be instrumented.
111 * This handles lockdep, RCU (context tracking) and tracing state.
113 * This is invoked when there is extra architecture specific functionality
114 * to be done between establishing state and handling user mode entry work.
116 void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
119 * syscall_enter_from_user_mode_work - Check and handle work before invoking
121 * @regs: Pointer to currents pt_regs
122 * @syscall: The syscall number
124 * Invoked from architecture specific syscall entry code with interrupts
125 * enabled after invoking syscall_enter_from_user_mode_prepare() and extra
126 * architecture specific work.
128 * Returns: The original or a modified syscall number
130 * If the returned syscall number is -1 then the syscall should be
131 * skipped. In this case the caller may invoke syscall_set_error() or
132 * syscall_set_return_value() first. If neither of those are called and -1
133 * is returned, then the syscall will fail with ENOSYS.
135 * It handles the following work items:
137 * 1) syscall_work flag dependent invocations of
138 * arch_syscall_enter_tracehook(), __secure_computing(), trace_sys_enter()
139 * 2) Invocation of audit_syscall_entry()
141 long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
144 * syscall_enter_from_user_mode - Establish state and check and handle work
145 * before invoking a syscall
146 * @regs: Pointer to currents pt_regs
147 * @syscall: The syscall number
149 * Invoked from architecture specific syscall entry code with interrupts
150 * disabled. The calling code has to be non-instrumentable. When the
151 * function returns all state is correct, interrupts are enabled and the
152 * subsequent functions can be instrumented.
154 * This is combination of syscall_enter_from_user_mode_prepare() and
155 * syscall_enter_from_user_mode_work().
157 * Returns: The original or a modified syscall number. See
158 * syscall_enter_from_user_mode_work() for further explanation.
160 long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
163 * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
164 * @ti_work: Cached TIF flags gathered with interrupts disabled
166 * Defaults to local_irq_enable(). Can be supplied by architecture specific
169 static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
171 #ifndef local_irq_enable_exit_to_user
172 static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
179 * local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
181 * Defaults to local_irq_disable(). Can be supplied by architecture specific
184 static inline void local_irq_disable_exit_to_user(void);
186 #ifndef local_irq_disable_exit_to_user
187 static inline void local_irq_disable_exit_to_user(void)
194 * arch_exit_to_user_mode_work - Architecture specific TIF work for exit
196 * @regs: Pointer to currents pt_regs
197 * @ti_work: Cached TIF flags gathered with interrupts disabled
199 * Invoked from exit_to_user_mode_loop() with interrupt enabled
201 * Defaults to NOOP. Can be supplied by architecture specific code.
203 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
204 unsigned long ti_work);
206 #ifndef arch_exit_to_user_mode_work
207 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
208 unsigned long ti_work)
214 * arch_exit_to_user_mode_prepare - Architecture specific preparation for
216 * @regs: Pointer to currents pt_regs
217 * @ti_work: Cached TIF flags gathered with interrupts disabled
219 * Invoked from exit_to_user_mode_prepare() with interrupt disabled as the last
220 * function before return. Defaults to NOOP.
222 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
223 unsigned long ti_work);
225 #ifndef arch_exit_to_user_mode_prepare
226 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
227 unsigned long ti_work)
233 * arch_exit_to_user_mode - Architecture specific final work before
236 * Invoked from exit_to_user_mode() with interrupt disabled as the last
237 * function before return. Defaults to NOOP.
239 * This needs to be __always_inline because it is non-instrumentable code
240 * invoked after context tracking switched to user mode.
242 * An architecture implementation must not do anything complex, no locking
243 * etc. The main purpose is for speculation mitigations.
245 static __always_inline void arch_exit_to_user_mode(void);
247 #ifndef arch_exit_to_user_mode
248 static __always_inline void arch_exit_to_user_mode(void) { }
252 * arch_do_signal_or_restart - Architecture specific signal delivery function
253 * @regs: Pointer to currents pt_regs
254 * @has_signal: actual signal to handle
256 * Invoked from exit_to_user_mode_loop().
258 void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal);
261 * arch_syscall_exit_tracehook - Wrapper around tracehook_report_syscall_exit()
262 * @regs: Pointer to currents pt_regs
263 * @step: Indicator for single step
265 * Defaults to tracehook_report_syscall_exit(). Can be replaced by
266 * architecture specific code.
268 * Invoked from syscall_exit_to_user_mode()
270 static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step);
272 #ifndef arch_syscall_exit_tracehook
273 static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step)
275 tracehook_report_syscall_exit(regs, step);
280 * syscall_exit_to_user_mode - Handle work before returning to user mode
281 * @regs: Pointer to currents pt_regs
283 * Invoked with interrupts enabled and fully valid regs. Returns with all
284 * work handled, interrupts disabled such that the caller can immediately
285 * switch to user mode. Called from architecture specific syscall and ret
289 * 1) One-time syscall exit work:
290 * - rseq syscall exit
293 * - tracehook (single stepping)
295 * 2) Preparatory work
296 * - Exit to user mode loop (common TIF handling). Invokes
297 * arch_exit_to_user_mode_work() for architecture specific TIF work
298 * - Architecture specific one time work arch_exit_to_user_mode_prepare()
299 * - Address limit and lockdep checks
301 * 3) Final transition (lockdep, tracing, context tracking, RCU). Invokes
302 * arch_exit_to_user_mode() to handle e.g. speculation mitigations
304 void syscall_exit_to_user_mode(struct pt_regs *regs);
307 * irqentry_enter_from_user_mode - Establish state before invoking the irq handler
308 * @regs: Pointer to currents pt_regs
310 * Invoked from architecture specific entry code with interrupts disabled.
311 * Can only be called when the interrupt entry came from user mode. The
312 * calling code must be non-instrumentable. When the function returns all
313 * state is correct and the subsequent functions can be instrumented.
315 * The function establishes state (lockdep, RCU (context tracking), tracing)
317 void irqentry_enter_from_user_mode(struct pt_regs *regs);
320 * irqentry_exit_to_user_mode - Interrupt exit work
321 * @regs: Pointer to current's pt_regs
323 * Invoked with interrupts disbled and fully valid regs. Returns with all
324 * work handled, interrupts disabled such that the caller can immediately
325 * switch to user mode. Called from architecture specific interrupt
328 * The call order is #2 and #3 as described in syscall_exit_to_user_mode().
329 * Interrupt exit is not invoking #1 which is the syscall specific one time
332 void irqentry_exit_to_user_mode(struct pt_regs *regs);
334 #ifndef irqentry_state
336 * struct irqentry_state - Opaque object for exception state storage
337 * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
338 * exit path has to invoke rcu_irq_exit().
339 * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
340 * lockdep state is restored correctly on exit from nmi.
342 * This opaque object is filled in by the irqentry_*_enter() functions and
343 * must be passed back into the corresponding irqentry_*_exit() functions
344 * when the exception is complete.
346 * Callers of irqentry_*_[enter|exit]() must consider this structure opaque
347 * and all members private. Descriptions of the members are provided to aid in
348 * the maintenance of the irqentry_*() functions.
350 typedef struct irqentry_state {
359 * irqentry_enter - Handle state tracking on ordinary interrupt entries
360 * @regs: Pointer to pt_regs of interrupted context
363 * - lockdep irqflag state tracking as low level ASM entry disabled
366 * - Context tracking if the exception hit user mode.
368 * - The hardirq tracer to keep the state consistent as low level ASM
369 * entry disabled interrupts.
371 * As a precondition, this requires that the entry came from user mode,
372 * idle, or a kernel context in which RCU is watching.
374 * For kernel mode entries RCU handling is done conditional. If RCU is
375 * watching then the only RCU requirement is to check whether the tick has
376 * to be restarted. If RCU is not watching then rcu_irq_enter() has to be
377 * invoked on entry and rcu_irq_exit() on exit.
379 * Avoiding the rcu_irq_enter/exit() calls is an optimization but also
380 * solves the problem of kernel mode pagefaults which can schedule, which
381 * is not possible after invoking rcu_irq_enter() without undoing it.
383 * For user mode entries irqentry_enter_from_user_mode() is invoked to
384 * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
385 * would not be possible.
387 * Returns: An opaque object that must be passed to idtentry_exit()
389 irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
392 * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
394 * Conditional reschedule with additional sanity checks.
396 void irqentry_exit_cond_resched(void);
399 * irqentry_exit - Handle return from exception that used irqentry_enter()
400 * @regs: Pointer to pt_regs (exception entry regs)
401 * @state: Return value from matching call to irqentry_enter()
403 * Depending on the return target (kernel/user) this runs the necessary
404 * preemption and work checks if possible and required and returns to
405 * the caller with interrupts disabled and no further work pending.
407 * This is the last action before returning to the low level ASM code which
408 * just needs to return to the appropriate context.
410 * Counterpart to irqentry_enter().
412 void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
415 * irqentry_nmi_enter - Handle NMI entry
416 * @regs: Pointer to currents pt_regs
418 * Similar to irqentry_enter() but taking care of the NMI constraints.
420 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
423 * irqentry_nmi_exit - Handle return from NMI handling
424 * @regs: Pointer to pt_regs (NMI entry regs)
425 * @irq_state: Return value from matching call to irqentry_nmi_enter()
427 * Last action before returning to the low level assembly code.
429 * Counterpart to irqentry_nmi_enter().
431 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);