1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/context_tracking.h>
4 #include <linux/entry-common.h>
5 #include <linux/highmem.h>
6 #include <linux/livepatch.h>
7 #include <linux/audit.h>
11 #define CREATE_TRACE_POINTS
12 #include <trace/events/syscalls.h>
14 /* See comment for enter_from_user_mode() in entry-common.h */
15 static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
17 arch_check_user_regs(regs);
18 lockdep_hardirqs_off(CALLER_ADDR0);
20 CT_WARN_ON(ct_state() != CONTEXT_USER);
23 instrumentation_begin();
24 trace_hardirqs_off_finish();
25 instrumentation_end();
28 void noinstr enter_from_user_mode(struct pt_regs *regs)
30 __enter_from_user_mode(regs);
33 static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
35 if (unlikely(audit_context())) {
36 unsigned long args[6];
38 syscall_get_arguments(current, regs, args);
39 audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
43 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
49 * Handle Syscall User Dispatch. This must comes first, since
50 * the ABI here can be something that doesn't make sense for
51 * other syscall_work features.
53 if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
54 if (syscall_user_dispatch(regs))
59 if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
60 ret = arch_syscall_enter_tracehook(regs);
61 if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
65 /* Do seccomp after ptrace, to catch any tracer changes. */
66 if (work & SYSCALL_WORK_SECCOMP) {
67 ret = __secure_computing(NULL);
72 /* Either of the above might have changed the syscall number */
73 syscall = syscall_get_nr(current, regs);
75 if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT))
76 trace_sys_enter(regs, syscall);
78 syscall_enter_audit(regs, syscall);
80 return ret ? : syscall;
83 static __always_inline long
84 __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
86 unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
88 if (work & SYSCALL_WORK_ENTER)
89 syscall = syscall_trace_enter(regs, syscall, work);
94 long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
96 return __syscall_enter_from_user_work(regs, syscall);
99 noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
103 __enter_from_user_mode(regs);
105 instrumentation_begin();
107 ret = __syscall_enter_from_user_work(regs, syscall);
108 instrumentation_end();
113 noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
115 __enter_from_user_mode(regs);
116 instrumentation_begin();
118 instrumentation_end();
121 /* See comment for exit_to_user_mode() in entry-common.h */
122 static __always_inline void __exit_to_user_mode(void)
124 instrumentation_begin();
125 trace_hardirqs_on_prepare();
126 lockdep_hardirqs_on_prepare(CALLER_ADDR0);
127 instrumentation_end();
130 arch_exit_to_user_mode();
131 lockdep_hardirqs_on(CALLER_ADDR0);
134 void noinstr exit_to_user_mode(void)
136 __exit_to_user_mode();
139 /* Workaround to allow gradual conversion of architecture code */
140 void __weak arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) { }
142 static void handle_signal_work(struct pt_regs *regs, unsigned long ti_work)
144 if (ti_work & _TIF_NOTIFY_SIGNAL)
145 tracehook_notify_signal();
147 arch_do_signal_or_restart(regs, ti_work & _TIF_SIGPENDING);
150 static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
151 unsigned long ti_work)
154 * Before returning to user space ensure that all pending work
155 * items have been completed.
157 while (ti_work & EXIT_TO_USER_MODE_WORK) {
159 local_irq_enable_exit_to_user(ti_work);
161 if (ti_work & _TIF_NEED_RESCHED)
164 if (ti_work & _TIF_UPROBE)
165 uprobe_notify_resume(regs);
167 if (ti_work & _TIF_PATCH_PENDING)
168 klp_update_patch_state(current);
170 if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
171 handle_signal_work(regs, ti_work);
173 if (ti_work & _TIF_NOTIFY_RESUME) {
174 tracehook_notify_resume(regs);
175 rseq_handle_notify_resume(NULL, regs);
178 /* Architecture specific TIF work */
179 arch_exit_to_user_mode_work(regs, ti_work);
182 * Disable interrupts and reevaluate the work flags as they
183 * might have changed while interrupts and preemption was
186 local_irq_disable_exit_to_user();
188 /* Check if any of the above work has queued a deferred wakeup */
189 rcu_nocb_flush_deferred_wakeup();
191 ti_work = READ_ONCE(current_thread_info()->flags);
194 /* Return the latest work state for arch_exit_to_user_mode() */
198 static void exit_to_user_mode_prepare(struct pt_regs *regs)
200 unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
202 lockdep_assert_irqs_disabled();
204 /* Flush pending rcuog wakeup before the last need_resched() check */
205 rcu_nocb_flush_deferred_wakeup();
207 if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
208 ti_work = exit_to_user_mode_loop(regs, ti_work);
210 arch_exit_to_user_mode_prepare(regs, ti_work);
212 /* Ensure that the address limit is intact and no locks are held */
213 addr_limit_user_check();
215 lockdep_assert_irqs_disabled();
220 * If SYSCALL_EMU is set, then the only reason to report is when
221 * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
222 * instruction has been already reported in syscall_enter_from_user_mode().
224 static inline bool report_single_step(unsigned long work)
226 if (work & SYSCALL_WORK_SYSCALL_EMU)
229 return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
232 static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
237 * If the syscall was rolled back due to syscall user dispatching,
238 * then the tracers below are not invoked for the same reason as
239 * the entry side was not invoked in syscall_trace_enter(): The ABI
240 * of these syscalls is unknown.
242 if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
243 if (unlikely(current->syscall_dispatch.on_dispatch)) {
244 current->syscall_dispatch.on_dispatch = false;
249 audit_syscall_exit(regs);
251 if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
252 trace_sys_exit(regs, syscall_get_return_value(current, regs));
254 step = report_single_step(work);
255 if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
256 arch_syscall_exit_tracehook(regs, step);
260 * Syscall specific exit to user mode preparation. Runs with interrupts
263 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
265 unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
266 unsigned long nr = syscall_get_nr(current, regs);
268 CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
270 if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
271 if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
278 * Do one-time syscall specific work. If these work items are
279 * enabled, we want to run them exactly once per syscall exit with
280 * interrupts enabled.
282 if (unlikely(work & SYSCALL_WORK_EXIT))
283 syscall_exit_work(regs, work);
286 static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs)
288 syscall_exit_to_user_mode_prepare(regs);
289 local_irq_disable_exit_to_user();
290 exit_to_user_mode_prepare(regs);
293 void syscall_exit_to_user_mode_work(struct pt_regs *regs)
295 __syscall_exit_to_user_mode_work(regs);
298 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
300 instrumentation_begin();
301 __syscall_exit_to_user_mode_work(regs);
302 instrumentation_end();
303 __exit_to_user_mode();
306 noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
308 __enter_from_user_mode(regs);
311 noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
313 instrumentation_begin();
314 exit_to_user_mode_prepare(regs);
315 instrumentation_end();
316 __exit_to_user_mode();
319 noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
321 irqentry_state_t ret = {
325 if (user_mode(regs)) {
326 irqentry_enter_from_user_mode(regs);
331 * If this entry hit the idle task invoke rcu_irq_enter() whether
332 * RCU is watching or not.
334 * Interrupts can nest when the first interrupt invokes softirq
335 * processing on return which enables interrupts.
337 * Scheduler ticks in the idle task can mark quiescent state and
338 * terminate a grace period, if and only if the timer interrupt is
339 * not nested into another interrupt.
341 * Checking for rcu_is_watching() here would prevent the nesting
342 * interrupt to invoke rcu_irq_enter(). If that nested interrupt is
343 * the tick then rcu_flavor_sched_clock_irq() would wrongfully
344 * assume that it is the first interrupt and eventually claim
345 * quiescent state and end grace periods prematurely.
347 * Unconditionally invoke rcu_irq_enter() so RCU state stays
350 * TINY_RCU does not support EQS, so let the compiler eliminate
351 * this part when enabled.
353 if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
355 * If RCU is not watching then the same careful
356 * sequence vs. lockdep and tracing is required
357 * as in irqentry_enter_from_user_mode().
359 lockdep_hardirqs_off(CALLER_ADDR0);
361 instrumentation_begin();
362 trace_hardirqs_off_finish();
363 instrumentation_end();
370 * If RCU is watching then RCU only wants to check whether it needs
371 * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
372 * already contains a warning when RCU is not watching, so no point
373 * in having another one here.
375 lockdep_hardirqs_off(CALLER_ADDR0);
376 instrumentation_begin();
377 rcu_irq_enter_check_tick();
378 trace_hardirqs_off_finish();
379 instrumentation_end();
384 void irqentry_exit_cond_resched(void)
386 if (!preempt_count()) {
387 /* Sanity check RCU and thread stack */
388 rcu_irq_exit_check_preempt();
389 if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
390 WARN_ON_ONCE(!on_thread_stack());
392 preempt_schedule_irq();
395 #ifdef CONFIG_PREEMPT_DYNAMIC
396 DEFINE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
399 noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
401 lockdep_assert_irqs_disabled();
403 /* Check whether this returns to user mode */
404 if (user_mode(regs)) {
405 irqentry_exit_to_user_mode(regs);
406 } else if (!regs_irqs_disabled(regs)) {
408 * If RCU was not watching on entry this needs to be done
409 * carefully and needs the same ordering of lockdep/tracing
410 * and RCU as the return to user mode path.
412 if (state.exit_rcu) {
413 instrumentation_begin();
414 /* Tell the tracer that IRET will enable interrupts */
415 trace_hardirqs_on_prepare();
416 lockdep_hardirqs_on_prepare(CALLER_ADDR0);
417 instrumentation_end();
419 lockdep_hardirqs_on(CALLER_ADDR0);
423 instrumentation_begin();
424 if (IS_ENABLED(CONFIG_PREEMPTION)) {
425 #ifdef CONFIG_PREEMPT_DYNAMIC
426 static_call(irqentry_exit_cond_resched)();
428 irqentry_exit_cond_resched();
431 /* Covers both tracing and lockdep */
433 instrumentation_end();
436 * IRQ flags state is correct already. Just tell RCU if it
437 * was not watching on entry.
444 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
446 irqentry_state_t irq_state;
448 irq_state.lockdep = lockdep_hardirqs_enabled();
451 lockdep_hardirqs_off(CALLER_ADDR0);
452 lockdep_hardirq_enter();
455 instrumentation_begin();
456 trace_hardirqs_off_finish();
458 instrumentation_end();
463 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
465 instrumentation_begin();
467 if (irq_state.lockdep) {
468 trace_hardirqs_on_prepare();
469 lockdep_hardirqs_on_prepare(CALLER_ADDR0);
471 instrumentation_end();
474 lockdep_hardirq_exit();
475 if (irq_state.lockdep)
476 lockdep_hardirqs_on(CALLER_ADDR0);