// SPDX-License-Identifier: GPL-2.0 #include <linux/context_tracking.h>#include <linux/entry-common.h>#include <linux/resume_user_mode.h>#include <linux/highmem.h>#include <linux/jump_label.h>#include <linux/kmsan.h>#include <linux/livepatch.h>#include <linux/audit.h>#include <linux/tick.h> #include "common.h" #define CREATE_TRACE_POINTS#include <trace/events/syscalls.h> static inline void syscall_enter_audit(struct pt_regs *regs, long syscall){	if (unlikely(audit_context())) {		unsigned long args[6]; 		syscall_get_arguments(current, regs, args);		audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);	}} long syscall_trace_enter(struct pt_regs *regs, long syscall,				unsigned long work){	long ret = 0; 	/*	 * Handle Syscall User Dispatch.  This must comes first, since	 * the ABI here can be something that doesn't make sense for	 * other syscall_work features.	 */	if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {		if (syscall_user_dispatch(regs))			return -1L;	} 	/* Handle ptrace */	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {		ret = ptrace_report_syscall_entry(regs);		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))			return -1L;	} 	/* Do seccomp after ptrace, to catch any tracer changes. */	if (work & SYSCALL_WORK_SECCOMP) {		ret = __secure_computing(NULL);		if (ret == -1L)			return ret;	} 	/* Either of the above might have changed the syscall number */	syscall = syscall_get_nr(current, regs); 	if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT)) {		trace_sys_enter(regs, syscall);		/*		 * Probes or BPF hooks in the tracepoint may have changed the		 * system call number as well.		 */		syscall = syscall_get_nr(current, regs);	} 	syscall_enter_audit(regs, syscall); 	return ret ? : syscall;} noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs){	enter_from_user_mode(regs);	instrumentation_begin();	local_irq_enable();	instrumentation_end();} /* Workaround to allow gradual conversion of architecture code */void __weak arch_do_signal_or_restart(struct pt_regs *regs) { } /** * exit_to_user_mode_loop - do any pending work before leaving to user space * @regs:	Pointer to pt_regs on entry stack * @ti_work:	TIF work flags as read by the caller */__always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs,						     unsigned long ti_work){	/*	 * Before returning to user space ensure that all pending work	 * items have been completed.	 */	while (ti_work & EXIT_TO_USER_MODE_WORK) { 		local_irq_enable_exit_to_user(ti_work); 		if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY))			schedule(); 		if (ti_work & _TIF_UPROBE)			uprobe_notify_resume(regs); 		if (ti_work & _TIF_PATCH_PENDING)			klp_update_patch_state(current); 		if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))			arch_do_signal_or_restart(regs); 		if (ti_work & _TIF_NOTIFY_RESUME)			resume_user_mode_work(regs); 		/* Architecture specific TIF work */		arch_exit_to_user_mode_work(regs, ti_work); 		/*		 * Disable interrupts and reevaluate the work flags as they		 * might have changed while interrupts and preemption was		 * enabled above.		 */		local_irq_disable_exit_to_user(); 		/* Check if any of the above work has queued a deferred wakeup */		tick_nohz_user_enter_prepare(); 		ti_work = read_thread_flags();	} 	/* Return the latest work state for arch_exit_to_user_mode() */	return ti_work;} /* * If SYSCALL_EMU is set, then the only reason to report is when * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP).  This syscall * instruction has been already reported in syscall_enter_from_user_mode(). */static inline bool report_single_step(unsigned long work){	if (work & SYSCALL_WORK_SYSCALL_EMU)		return false; 	return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;} static void syscall_exit_work(struct pt_regs *regs, unsigned long work){	bool step; 	/*	 * If the syscall was rolled back due to syscall user dispatching,	 * then the tracers below are not invoked for the same reason as	 * the entry side was not invoked in syscall_trace_enter(): The ABI	 * of these syscalls is unknown.	 */	if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {		if (unlikely(current->syscall_dispatch.on_dispatch)) {			current->syscall_dispatch.on_dispatch = false;			return;		}	} 	audit_syscall_exit(regs); 	if (work & SYSCALL_WORK_SYSCALL_TRACEPOINT)		trace_sys_exit(regs, syscall_get_return_value(current, regs)); 	step = report_single_step(work);	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)		ptrace_report_syscall_exit(regs, step);} /* * Syscall specific exit to user mode preparation. Runs with interrupts * enabled. */static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs){	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);	unsigned long nr = syscall_get_nr(current, regs); 	CT_WARN_ON(ct_state() != CT_STATE_KERNEL); 	if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {		if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))			local_irq_enable();	} 	rseq_syscall(regs); 	/*	 * Do one-time syscall specific work. If these work items are	 * enabled, we want to run them exactly once per syscall exit with	 * interrupts enabled.	 */	if (unlikely(work & SYSCALL_WORK_EXIT))		syscall_exit_work(regs, work);} static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs){	syscall_exit_to_user_mode_prepare(regs);	local_irq_disable_exit_to_user();	exit_to_user_mode_prepare(regs);} void syscall_exit_to_user_mode_work(struct pt_regs *regs){	__syscall_exit_to_user_mode_work(regs);} __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs){	instrumentation_begin();	__syscall_exit_to_user_mode_work(regs);	instrumentation_end();	exit_to_user_mode();} noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs){	enter_from_user_mode(regs);} noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs){	instrumentation_begin();	exit_to_user_mode_prepare(regs);	instrumentation_end();	exit_to_user_mode();} noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs){	irqentry_state_t ret = {		.exit_rcu = false,	}; 	if (user_mode(regs)) {		irqentry_enter_from_user_mode(regs);		return ret;	} 	/*	 * If this entry hit the idle task invoke ct_irq_enter() whether	 * RCU is watching or not.	 *	 * Interrupts can nest when the first interrupt invokes softirq	 * processing on return which enables interrupts.	 *	 * Scheduler ticks in the idle task can mark quiescent state and	 * terminate a grace period, if and only if the timer interrupt is	 * not nested into another interrupt.	 *	 * Checking for rcu_is_watching() here would prevent the nesting	 * interrupt to invoke ct_irq_enter(). If that nested interrupt is	 * the tick then rcu_flavor_sched_clock_irq() would wrongfully	 * assume that it is the first interrupt and eventually claim	 * quiescent state and end grace periods prematurely.	 *	 * Unconditionally invoke ct_irq_enter() so RCU state stays	 * consistent.	 *	 * TINY_RCU does not support EQS, so let the compiler eliminate	 * this part when enabled.	 */	if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {		/*		 * If RCU is not watching then the same careful		 * sequence vs. lockdep and tracing is required		 * as in irqentry_enter_from_user_mode().		 */		lockdep_hardirqs_off(CALLER_ADDR0);		ct_irq_enter();		instrumentation_begin();		kmsan_unpoison_entry_regs(regs);		trace_hardirqs_off_finish();		instrumentation_end(); 		ret.exit_rcu = true;		return ret;	} 	/*	 * If RCU is watching then RCU only wants to check whether it needs	 * to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()	 * already contains a warning when RCU is not watching, so no point	 * in having another one here.	 */	lockdep_hardirqs_off(CALLER_ADDR0);	instrumentation_begin();	kmsan_unpoison_entry_regs(regs);	rcu_irq_enter_check_tick();	trace_hardirqs_off_finish();	instrumentation_end(); 	return ret;} void raw_irqentry_exit_cond_resched(void){	if (!preempt_count()) {		/* Sanity check RCU and thread stack */		rcu_irq_exit_check_preempt();		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))			WARN_ON_ONCE(!on_thread_stack());		if (need_resched())			preempt_schedule_irq();	}}#ifdef CONFIG_PREEMPT_DYNAMIC#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)DEFINE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);void dynamic_irqentry_exit_cond_resched(void){	if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))		return;	raw_irqentry_exit_cond_resched();}#endif#endif noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state){	lockdep_assert_irqs_disabled(); 	/* Check whether this returns to user mode */	if (user_mode(regs)) {		irqentry_exit_to_user_mode(regs);	} else if (!regs_irqs_disabled(regs)) {		/*		 * If RCU was not watching on entry this needs to be done		 * carefully and needs the same ordering of lockdep/tracing		 * and RCU as the return to user mode path.		 */		if (state.exit_rcu) {			instrumentation_begin();			/* Tell the tracer that IRET will enable interrupts */			trace_hardirqs_on_prepare();			lockdep_hardirqs_on_prepare();			instrumentation_end();			ct_irq_exit();			lockdep_hardirqs_on(CALLER_ADDR0);			return;		} 		instrumentation_begin();		if (IS_ENABLED(CONFIG_PREEMPTION))			irqentry_exit_cond_resched(); 		/* Covers both tracing and lockdep */		trace_hardirqs_on();		instrumentation_end();	} else {		/*		 * IRQ flags state is correct already. Just tell RCU if it		 * was not watching on entry.		 */		if (state.exit_rcu)			ct_irq_exit();	}} irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs){	irqentry_state_t irq_state; 	irq_state.lockdep = lockdep_hardirqs_enabled(); 	__nmi_enter();	lockdep_hardirqs_off(CALLER_ADDR0);	lockdep_hardirq_enter();	ct_nmi_enter(); 	instrumentation_begin();	kmsan_unpoison_entry_regs(regs);	trace_hardirqs_off_finish();	ftrace_nmi_enter();	instrumentation_end(); 	return irq_state;} void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state){	instrumentation_begin();	ftrace_nmi_exit();	if (irq_state.lockdep) {		trace_hardirqs_on_prepare();		lockdep_hardirqs_on_prepare();	}	instrumentation_end(); 	ct_nmi_exit();	lockdep_hardirq_exit();	if (irq_state.lockdep)		lockdep_hardirqs_on(CALLER_ADDR0);	__nmi_exit();}