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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - kernel/entry/common.c
1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/context_tracking.h>
4 #include <linux/entry-common.h>
5 #include <linux/livepatch.h>
6 #include <linux/audit.h>
8 #define CREATE_TRACE_POINTS
9 #include <trace/events/syscalls.h>
12 * enter_from_user_mode - Establish state when coming from user mode
14 * Syscall/interrupt entry disables interrupts, but user mode is traced as
15 * interrupts enabled. Also with NO_HZ_FULL RCU might be idle.
17 * 1) Tell lockdep that interrupts are disabled
18 * 2) Invoke context tracking if enabled to reactivate RCU
19 * 3) Trace interrupts off state
21 static __always_inline
void enter_from_user_mode(struct pt_regs
*regs
)
23 arch_check_user_regs(regs
);
24 lockdep_hardirqs_off(CALLER_ADDR0
);
26 CT_WARN_ON(ct_state() != CONTEXT_USER
);
29 instrumentation_begin();
30 trace_hardirqs_off_finish();
31 instrumentation_end();
34 static inline void syscall_enter_audit(struct pt_regs
*regs
, long syscall
)
36 if (unlikely(audit_context())) {
37 unsigned long args
[6];
39 syscall_get_arguments(current
, regs
, args
);
40 audit_syscall_entry(syscall
, args
[0], args
[1], args
[2], args
[3]);
44 static long syscall_trace_enter(struct pt_regs
*regs
, long syscall
,
45 unsigned long ti_work
)
50 if (ti_work
& (_TIF_SYSCALL_TRACE
| _TIF_SYSCALL_EMU
)) {
51 ret
= arch_syscall_enter_tracehook(regs
);
52 if (ret
|| (ti_work
& _TIF_SYSCALL_EMU
))
56 /* Do seccomp after ptrace, to catch any tracer changes. */
57 if (ti_work
& _TIF_SECCOMP
) {
58 ret
= __secure_computing(NULL
);
63 /* Either of the above might have changed the syscall number */
64 syscall
= syscall_get_nr(current
, regs
);
66 if (unlikely(ti_work
& _TIF_SYSCALL_TRACEPOINT
))
67 trace_sys_enter(regs
, syscall
);
69 syscall_enter_audit(regs
, syscall
);
71 return ret
? : syscall
;
74 static __always_inline
long
75 __syscall_enter_from_user_work(struct pt_regs
*regs
, long syscall
)
77 unsigned long ti_work
;
79 ti_work
= READ_ONCE(current_thread_info()->flags
);
80 if (ti_work
& SYSCALL_ENTER_WORK
)
81 syscall
= syscall_trace_enter(regs
, syscall
, ti_work
);
86 long syscall_enter_from_user_mode_work(struct pt_regs
*regs
, long syscall
)
88 return __syscall_enter_from_user_work(regs
, syscall
);
91 noinstr
long syscall_enter_from_user_mode(struct pt_regs
*regs
, long syscall
)
95 enter_from_user_mode(regs
);
97 instrumentation_begin();
99 ret
= __syscall_enter_from_user_work(regs
, syscall
);
100 instrumentation_end();
105 noinstr
void syscall_enter_from_user_mode_prepare(struct pt_regs
*regs
)
107 enter_from_user_mode(regs
);
108 instrumentation_begin();
110 instrumentation_end();
114 * exit_to_user_mode - Fixup state when exiting to user mode
116 * Syscall/interupt exit enables interrupts, but the kernel state is
117 * interrupts disabled when this is invoked. Also tell RCU about it.
119 * 1) Trace interrupts on state
120 * 2) Invoke context tracking if enabled to adjust RCU state
121 * 3) Invoke architecture specific last minute exit code, e.g. speculation
123 * 4) Tell lockdep that interrupts are enabled
125 static __always_inline
void exit_to_user_mode(void)
127 instrumentation_begin();
128 trace_hardirqs_on_prepare();
129 lockdep_hardirqs_on_prepare(CALLER_ADDR0
);
130 instrumentation_end();
133 arch_exit_to_user_mode();
134 lockdep_hardirqs_on(CALLER_ADDR0
);
137 /* Workaround to allow gradual conversion of architecture code */
138 void __weak
arch_do_signal(struct pt_regs
*regs
) { }
140 static unsigned long exit_to_user_mode_loop(struct pt_regs
*regs
,
141 unsigned long ti_work
)
144 * Before returning to user space ensure that all pending work
145 * items have been completed.
147 while (ti_work
& EXIT_TO_USER_MODE_WORK
) {
149 local_irq_enable_exit_to_user(ti_work
);
151 if (ti_work
& _TIF_NEED_RESCHED
)
154 if (ti_work
& _TIF_UPROBE
)
155 uprobe_notify_resume(regs
);
157 if (ti_work
& _TIF_PATCH_PENDING
)
158 klp_update_patch_state(current
);
160 if (ti_work
& _TIF_SIGPENDING
)
161 arch_do_signal(regs
);
163 if (ti_work
& _TIF_NOTIFY_RESUME
) {
164 tracehook_notify_resume(regs
);
165 rseq_handle_notify_resume(NULL
, regs
);
168 /* Architecture specific TIF work */
169 arch_exit_to_user_mode_work(regs
, ti_work
);
172 * Disable interrupts and reevaluate the work flags as they
173 * might have changed while interrupts and preemption was
176 local_irq_disable_exit_to_user();
177 ti_work
= READ_ONCE(current_thread_info()->flags
);
180 /* Return the latest work state for arch_exit_to_user_mode() */
184 static void exit_to_user_mode_prepare(struct pt_regs
*regs
)
186 unsigned long ti_work
= READ_ONCE(current_thread_info()->flags
);
188 lockdep_assert_irqs_disabled();
190 if (unlikely(ti_work
& EXIT_TO_USER_MODE_WORK
))
191 ti_work
= exit_to_user_mode_loop(regs
, ti_work
);
193 arch_exit_to_user_mode_prepare(regs
, ti_work
);
195 /* Ensure that the address limit is intact and no locks are held */
196 addr_limit_user_check();
197 lockdep_assert_irqs_disabled();
201 #ifndef _TIF_SINGLESTEP
202 static inline bool report_single_step(unsigned long ti_work
)
208 * If TIF_SYSCALL_EMU is set, then the only reason to report is when
209 * TIF_SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall
210 * instruction has been already reported in syscall_enter_from_user_mode().
212 #define SYSEMU_STEP (_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)
214 static inline bool report_single_step(unsigned long ti_work
)
216 return (ti_work
& SYSEMU_STEP
) == _TIF_SINGLESTEP
;
220 static void syscall_exit_work(struct pt_regs
*regs
, unsigned long ti_work
)
224 audit_syscall_exit(regs
);
226 if (ti_work
& _TIF_SYSCALL_TRACEPOINT
)
227 trace_sys_exit(regs
, syscall_get_return_value(current
, regs
));
229 step
= report_single_step(ti_work
);
230 if (step
|| ti_work
& _TIF_SYSCALL_TRACE
)
231 arch_syscall_exit_tracehook(regs
, step
);
235 * Syscall specific exit to user mode preparation. Runs with interrupts
238 static void syscall_exit_to_user_mode_prepare(struct pt_regs
*regs
)
240 u32 cached_flags
= READ_ONCE(current_thread_info()->flags
);
241 unsigned long nr
= syscall_get_nr(current
, regs
);
243 CT_WARN_ON(ct_state() != CONTEXT_KERNEL
);
245 if (IS_ENABLED(CONFIG_PROVE_LOCKING
)) {
246 if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr
))
253 * Do one-time syscall specific work. If these work items are
254 * enabled, we want to run them exactly once per syscall exit with
255 * interrupts enabled.
257 if (unlikely(cached_flags
& SYSCALL_EXIT_WORK
))
258 syscall_exit_work(regs
, cached_flags
);
261 __visible noinstr
void syscall_exit_to_user_mode(struct pt_regs
*regs
)
263 instrumentation_begin();
264 syscall_exit_to_user_mode_prepare(regs
);
265 local_irq_disable_exit_to_user();
266 exit_to_user_mode_prepare(regs
);
267 instrumentation_end();
271 noinstr
void irqentry_enter_from_user_mode(struct pt_regs
*regs
)
273 enter_from_user_mode(regs
);
276 noinstr
void irqentry_exit_to_user_mode(struct pt_regs
*regs
)
278 instrumentation_begin();
279 exit_to_user_mode_prepare(regs
);
280 instrumentation_end();
284 noinstr irqentry_state_t
irqentry_enter(struct pt_regs
*regs
)
286 irqentry_state_t ret
= {
290 if (user_mode(regs
)) {
291 irqentry_enter_from_user_mode(regs
);
296 * If this entry hit the idle task invoke rcu_irq_enter() whether
297 * RCU is watching or not.
299 * Interupts can nest when the first interrupt invokes softirq
300 * processing on return which enables interrupts.
302 * Scheduler ticks in the idle task can mark quiescent state and
303 * terminate a grace period, if and only if the timer interrupt is
304 * not nested into another interrupt.
306 * Checking for rcu_is_watching() here would prevent the nesting
307 * interrupt to invoke rcu_irq_enter(). If that nested interrupt is
308 * the tick then rcu_flavor_sched_clock_irq() would wrongfully
309 * assume that it is the first interupt and eventually claim
310 * quiescient state and end grace periods prematurely.
312 * Unconditionally invoke rcu_irq_enter() so RCU state stays
315 * TINY_RCU does not support EQS, so let the compiler eliminate
316 * this part when enabled.
318 if (!IS_ENABLED(CONFIG_TINY_RCU
) && is_idle_task(current
)) {
320 * If RCU is not watching then the same careful
321 * sequence vs. lockdep and tracing is required
322 * as in irq_enter_from_user_mode().
324 lockdep_hardirqs_off(CALLER_ADDR0
);
326 instrumentation_begin();
327 trace_hardirqs_off_finish();
328 instrumentation_end();
335 * If RCU is watching then RCU only wants to check whether it needs
336 * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
337 * already contains a warning when RCU is not watching, so no point
338 * in having another one here.
340 lockdep_hardirqs_off(CALLER_ADDR0
);
341 instrumentation_begin();
342 rcu_irq_enter_check_tick();
343 trace_hardirqs_off_finish();
344 instrumentation_end();
349 void irqentry_exit_cond_resched(void)
351 if (!preempt_count()) {
352 /* Sanity check RCU and thread stack */
353 rcu_irq_exit_check_preempt();
354 if (IS_ENABLED(CONFIG_DEBUG_ENTRY
))
355 WARN_ON_ONCE(!on_thread_stack());
357 preempt_schedule_irq();
361 noinstr
void irqentry_exit(struct pt_regs
*regs
, irqentry_state_t state
)
363 lockdep_assert_irqs_disabled();
365 /* Check whether this returns to user mode */
366 if (user_mode(regs
)) {
367 irqentry_exit_to_user_mode(regs
);
368 } else if (!regs_irqs_disabled(regs
)) {
370 * If RCU was not watching on entry this needs to be done
371 * carefully and needs the same ordering of lockdep/tracing
372 * and RCU as the return to user mode path.
374 if (state
.exit_rcu
) {
375 instrumentation_begin();
376 /* Tell the tracer that IRET will enable interrupts */
377 trace_hardirqs_on_prepare();
378 lockdep_hardirqs_on_prepare(CALLER_ADDR0
);
379 instrumentation_end();
381 lockdep_hardirqs_on(CALLER_ADDR0
);
385 instrumentation_begin();
386 if (IS_ENABLED(CONFIG_PREEMPTION
))
387 irqentry_exit_cond_resched();
388 /* Covers both tracing and lockdep */
390 instrumentation_end();
393 * IRQ flags state is correct already. Just tell RCU if it
394 * was not watching on entry.