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- // 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>
- /* See comment for enter_from_user_mode() in entry-common.h */
- static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
- {
- arch_enter_from_user_mode(regs);
- lockdep_hardirqs_off(CALLER_ADDR0);
- CT_WARN_ON(__ct_state() != CONTEXT_USER);
- user_exit_irqoff();
- instrumentation_begin();
- kmsan_unpoison_entry_regs(regs);
- trace_hardirqs_off_finish();
- instrumentation_end();
- }
- void noinstr enter_from_user_mode(struct pt_regs *regs)
- {
- __enter_from_user_mode(regs);
- }
- 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]);
- }
- }
- static 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);
- syscall_enter_audit(regs, syscall);
- return ret ? : syscall;
- }
- static __always_inline long
- __syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
- {
- unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
- if (work & SYSCALL_WORK_ENTER)
- syscall = syscall_trace_enter(regs, syscall, work);
- return syscall;
- }
- long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
- {
- return __syscall_enter_from_user_work(regs, syscall);
- }
- noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
- {
- long ret;
- __enter_from_user_mode(regs);
- instrumentation_begin();
- local_irq_enable();
- ret = __syscall_enter_from_user_work(regs, syscall);
- instrumentation_end();
- return ret;
- }
- noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
- {
- __enter_from_user_mode(regs);
- instrumentation_begin();
- local_irq_enable();
- instrumentation_end();
- }
- /* See comment for exit_to_user_mode() in entry-common.h */
- static __always_inline void __exit_to_user_mode(void)
- {
- instrumentation_begin();
- trace_hardirqs_on_prepare();
- lockdep_hardirqs_on_prepare();
- instrumentation_end();
- user_enter_irqoff();
- arch_exit_to_user_mode();
- lockdep_hardirqs_on(CALLER_ADDR0);
- }
- void noinstr exit_to_user_mode(void)
- {
- __exit_to_user_mode();
- }
- /* Workaround to allow gradual conversion of architecture code */
- void __weak arch_do_signal_or_restart(struct pt_regs *regs) { }
- static 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)
- 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;
- }
- static void exit_to_user_mode_prepare(struct pt_regs *regs)
- {
- unsigned long ti_work;
- lockdep_assert_irqs_disabled();
- /* Flush pending rcuog wakeup before the last need_resched() check */
- tick_nohz_user_enter_prepare();
- ti_work = read_thread_flags();
- if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
- ti_work = exit_to_user_mode_loop(regs, ti_work);
- arch_exit_to_user_mode_prepare(regs, ti_work);
- /* Ensure that the address limit is intact and no locks are held */
- addr_limit_user_check();
- kmap_assert_nomap();
- lockdep_assert_irqs_disabled();
- lockdep_sys_exit();
- }
- /*
- * 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() != CONTEXT_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();
- }
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