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();
187 ti_work = READ_ONCE(current_thread_info()->flags);
190 /* Return the latest work state for arch_exit_to_user_mode() */
194 static void exit_to_user_mode_prepare(struct pt_regs *regs)
196 unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
198 lockdep_assert_irqs_disabled();
200 if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
201 ti_work = exit_to_user_mode_loop(regs, ti_work);
203 arch_exit_to_user_mode_prepare(regs, ti_work);
205 /* Ensure that the address limit is intact and no locks are held */
206 addr_limit_user_check();
208 lockdep_assert_irqs_disabled();
213 * If SYSCALL_EMU is set, then the only reason to report is when
214 * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
215 * instruction has been already reported in syscall_enter_from_user_mode().
217 static inline bool report_single_step(unsigned long work)
219 if (work & SYSCALL_WORK_SYSCALL_EMU)
222 return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
225 static void syscall_exit_work(struct pt_regs *regs, unsigned long work)
230 * If the syscall was rolled back due to syscall user dispatching,
231 * then the tracers below are not invoked for the same reason as
232 * the entry side was not invoked in syscall_trace_enter(): The ABI
233 * of these syscalls is unknown.
235 if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
236 if (unlikely(current->syscall_dispatch.on_dispatch)) {
237 current->syscall_dispatch.on_dispatch = false;
242 audit_syscall_exit(regs);
244 if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)
245 trace_sys_exit(regs, syscall_get_return_value(current, regs));
247 step = report_single_step(work);
248 if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
249 arch_syscall_exit_tracehook(regs, step);
253 * Syscall specific exit to user mode preparation. Runs with interrupts
256 static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs)
258 unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
259 unsigned long nr = syscall_get_nr(current, regs);
261 CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
263 if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
264 if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
271 * Do one-time syscall specific work. If these work items are
272 * enabled, we want to run them exactly once per syscall exit with
273 * interrupts enabled.
275 if (unlikely(work & SYSCALL_WORK_EXIT))
276 syscall_exit_work(regs, work);
279 static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs)
281 syscall_exit_to_user_mode_prepare(regs);
282 local_irq_disable_exit_to_user();
283 exit_to_user_mode_prepare(regs);
286 void syscall_exit_to_user_mode_work(struct pt_regs *regs)
288 __syscall_exit_to_user_mode_work(regs);
291 __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs)
293 instrumentation_begin();
294 __syscall_exit_to_user_mode_work(regs);
295 instrumentation_end();
296 __exit_to_user_mode();
299 noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
301 __enter_from_user_mode(regs);
304 noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs)
306 instrumentation_begin();
307 exit_to_user_mode_prepare(regs);
308 instrumentation_end();
309 __exit_to_user_mode();
312 noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
314 irqentry_state_t ret = {
318 if (user_mode(regs)) {
319 irqentry_enter_from_user_mode(regs);
324 * If this entry hit the idle task invoke rcu_irq_enter() whether
325 * RCU is watching or not.
327 * Interrupts can nest when the first interrupt invokes softirq
328 * processing on return which enables interrupts.
330 * Scheduler ticks in the idle task can mark quiescent state and
331 * terminate a grace period, if and only if the timer interrupt is
332 * not nested into another interrupt.
334 * Checking for rcu_is_watching() here would prevent the nesting
335 * interrupt to invoke rcu_irq_enter(). If that nested interrupt is
336 * the tick then rcu_flavor_sched_clock_irq() would wrongfully
337 * assume that it is the first interupt and eventually claim
338 * quiescent state and end grace periods prematurely.
340 * Unconditionally invoke rcu_irq_enter() so RCU state stays
343 * TINY_RCU does not support EQS, so let the compiler eliminate
344 * this part when enabled.
346 if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
348 * If RCU is not watching then the same careful
349 * sequence vs. lockdep and tracing is required
350 * as in irqentry_enter_from_user_mode().
352 lockdep_hardirqs_off(CALLER_ADDR0);
354 instrumentation_begin();
355 trace_hardirqs_off_finish();
356 instrumentation_end();
363 * If RCU is watching then RCU only wants to check whether it needs
364 * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
365 * already contains a warning when RCU is not watching, so no point
366 * in having another one here.
368 lockdep_hardirqs_off(CALLER_ADDR0);
369 instrumentation_begin();
370 rcu_irq_enter_check_tick();
371 trace_hardirqs_off_finish();
372 instrumentation_end();
377 void irqentry_exit_cond_resched(void)
379 if (!preempt_count()) {
380 /* Sanity check RCU and thread stack */
381 rcu_irq_exit_check_preempt();
382 if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
383 WARN_ON_ONCE(!on_thread_stack());
385 preempt_schedule_irq();
389 noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
391 lockdep_assert_irqs_disabled();
393 /* Check whether this returns to user mode */
394 if (user_mode(regs)) {
395 irqentry_exit_to_user_mode(regs);
396 } else if (!regs_irqs_disabled(regs)) {
398 * If RCU was not watching on entry this needs to be done
399 * carefully and needs the same ordering of lockdep/tracing
400 * and RCU as the return to user mode path.
402 if (state.exit_rcu) {
403 instrumentation_begin();
404 /* Tell the tracer that IRET will enable interrupts */
405 trace_hardirqs_on_prepare();
406 lockdep_hardirqs_on_prepare(CALLER_ADDR0);
407 instrumentation_end();
409 lockdep_hardirqs_on(CALLER_ADDR0);
413 instrumentation_begin();
414 if (IS_ENABLED(CONFIG_PREEMPTION))
415 irqentry_exit_cond_resched();
416 /* Covers both tracing and lockdep */
418 instrumentation_end();
421 * IRQ flags state is correct already. Just tell RCU if it
422 * was not watching on entry.
429 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
431 irqentry_state_t irq_state;
433 irq_state.lockdep = lockdep_hardirqs_enabled();
436 lockdep_hardirqs_off(CALLER_ADDR0);
437 lockdep_hardirq_enter();
440 instrumentation_begin();
441 trace_hardirqs_off_finish();
443 instrumentation_end();
448 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
450 instrumentation_begin();
452 if (irq_state.lockdep) {
453 trace_hardirqs_on_prepare();
454 lockdep_hardirqs_on_prepare(CALLER_ADDR0);
456 instrumentation_end();
459 lockdep_hardirq_exit();
460 if (irq_state.lockdep)
461 lockdep_hardirqs_on(CALLER_ADDR0);