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 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __LINUX_ENTRYCOMMON_H
 #define __LINUX_ENTRYCOMMON_H
 
 #include <linux/static_call_types.h>
 #include <linux/ptrace.h>
 #include <linux/syscalls.h>
 #include <linux/seccomp.h>
 #include <linux/sched.h>
 
 #include <asm/entry-common.h>
 
 /*
  * Define dummy _TIF work flags if not defined by the architecture or for
  * disabled functionality.
  */
 #ifndef _TIF_PATCH_PENDING
 # define _TIF_PATCH_PENDING     (0)
 #endif
 
 #ifndef _TIF_UPROBE
 # define _TIF_UPROBE            (0)
 #endif
 
 /*
  * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
  */
 #ifndef ARCH_SYSCALL_WORK_ENTER
 # define ARCH_SYSCALL_WORK_ENTER    (0)
 #endif
 
 /*
  * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
  */
 #ifndef ARCH_SYSCALL_WORK_EXIT
 # define ARCH_SYSCALL_WORK_EXIT     (0)
 #endif
 
 #define SYSCALL_WORK_ENTER  (SYSCALL_WORK_SECCOMP |         \
                  SYSCALL_WORK_SYSCALL_TRACEPOINT |  \
                  SYSCALL_WORK_SYSCALL_TRACE |       \
                  SYSCALL_WORK_SYSCALL_EMU |     \
                  SYSCALL_WORK_SYSCALL_AUDIT |       \
                  SYSCALL_WORK_SYSCALL_USER_DISPATCH |   \
                  ARCH_SYSCALL_WORK_ENTER)
 #define SYSCALL_WORK_EXIT   (SYSCALL_WORK_SYSCALL_TRACEPOINT |  \
                  SYSCALL_WORK_SYSCALL_TRACE |       \
                  SYSCALL_WORK_SYSCALL_AUDIT |       \
                  SYSCALL_WORK_SYSCALL_USER_DISPATCH |   \
                  SYSCALL_WORK_SYSCALL_EXIT_TRAP |   \
                  ARCH_SYSCALL_WORK_EXIT)
 
 /*
  * TIF flags handled in exit_to_user_mode_loop()
  */
 #ifndef ARCH_EXIT_TO_USER_MODE_WORK
 # define ARCH_EXIT_TO_USER_MODE_WORK        (0)
 #endif
 
 #define EXIT_TO_USER_MODE_WORK                      \
     (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE |       \
      _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL |  \
      ARCH_EXIT_TO_USER_MODE_WORK)
 
 /**
  * arch_enter_from_user_mode - Architecture specific sanity check for user mode regs
  * @regs:   Pointer to currents pt_regs
  *
  * Defaults to an empty implementation. Can be replaced by architecture
  * specific code.
  *
  * Invoked from syscall_enter_from_user_mode() in the non-instrumentable
  * section. Use __always_inline so the compiler cannot push it out of line
  * and make it instrumentable.
  */
 static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs);
 
 #ifndef arch_enter_from_user_mode
 static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {}
 #endif
 
 /**
  * enter_from_user_mode - Establish state when coming from user mode
  *
  * Syscall/interrupt entry disables interrupts, but user mode is traced as
  * interrupts enabled. Also with NO_HZ_FULL RCU might be idle.
  *
  * 1) Tell lockdep that interrupts are disabled
  * 2) Invoke context tracking if enabled to reactivate RCU
  * 3) Trace interrupts off state
  *
  * Invoked from architecture specific syscall entry code with interrupts
  * disabled. The calling code has to be non-instrumentable. When the
  * function returns all state is correct and interrupts are still
  * disabled. The subsequent functions can be instrumented.
  *
  * This is invoked when there is architecture specific functionality to be
  * done between establishing state and enabling interrupts. The caller must
  * enable interrupts before invoking syscall_enter_from_user_mode_work().
  */
 void enter_from_user_mode(struct pt_regs *regs);
 
 /**
  * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
  * @regs:   Pointer to currents pt_regs
  *
  * Invoked from architecture specific syscall entry code with interrupts
  * disabled. The calling code has to be non-instrumentable. When the
  * function returns all state is correct, interrupts are enabled and the
  * subsequent functions can be instrumented.
  *
  * This handles lockdep, RCU (context tracking) and tracing state, i.e.
  * the functionality provided by enter_from_user_mode().
  *
  * This is invoked when there is extra architecture specific functionality
  * to be done between establishing state and handling user mode entry work.
  */
 void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
 
 /**
  * syscall_enter_from_user_mode_work - Check and handle work before invoking
  *                     a syscall
  * @regs:   Pointer to currents pt_regs
  * @syscall:    The syscall number
  *
  * Invoked from architecture specific syscall entry code with interrupts
  * enabled after invoking syscall_enter_from_user_mode_prepare() and extra
  * architecture specific work.
  *
  * Returns: The original or a modified syscall number
  *
  * If the returned syscall number is -1 then the syscall should be
  * skipped. In this case the caller may invoke syscall_set_error() or
  * syscall_set_return_value() first.  If neither of those are called and -1
  * is returned, then the syscall will fail with ENOSYS.
  *
  * It handles the following work items:
  *
  *  1) syscall_work flag dependent invocations of
  *     ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter()
  *  2) Invocation of audit_syscall_entry()
  */
 long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall);
 
 /**
  * syscall_enter_from_user_mode - Establish state and check and handle work
  *                before invoking a syscall
  * @regs:   Pointer to currents pt_regs
  * @syscall:    The syscall number
  *
  * Invoked from architecture specific syscall entry code with interrupts
  * disabled. The calling code has to be non-instrumentable. When the
  * function returns all state is correct, interrupts are enabled and the
  * subsequent functions can be instrumented.
  *
  * This is combination of syscall_enter_from_user_mode_prepare() and
  * syscall_enter_from_user_mode_work().
  *
  * Returns: The original or a modified syscall number. See
  * syscall_enter_from_user_mode_work() for further explanation.
  */
 long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
 
 /**
  * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
  * @ti_work:    Cached TIF flags gathered with interrupts disabled
  *
  * Defaults to local_irq_enable(). Can be supplied by architecture specific
  * code.
  */
 static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
 
 #ifndef local_irq_enable_exit_to_user
 static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
 {
     local_irq_enable();
 }
 #endif
 
 /**
  * local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
  *
  * Defaults to local_irq_disable(). Can be supplied by architecture specific
  * code.
  */
 static inline void local_irq_disable_exit_to_user(void);
 
 #ifndef local_irq_disable_exit_to_user
 static inline void local_irq_disable_exit_to_user(void)
 {
     local_irq_disable();
 }
 #endif
 
 /**
  * arch_exit_to_user_mode_work - Architecture specific TIF work for exit
  *               to user mode.
  * @regs:   Pointer to currents pt_regs
  * @ti_work:    Cached TIF flags gathered with interrupts disabled
  *
  * Invoked from exit_to_user_mode_loop() with interrupt enabled
  *
  * Defaults to NOOP. Can be supplied by architecture specific code.
  */
 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
                            unsigned long ti_work);
 
 #ifndef arch_exit_to_user_mode_work
 static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
                            unsigned long ti_work)
 {
 }
 #endif
 
 /**
  * arch_exit_to_user_mode_prepare - Architecture specific preparation for
  *                  exit to user mode.
  * @regs:   Pointer to currents pt_regs
  * @ti_work:    Cached TIF flags gathered with interrupts disabled
  *
  * Invoked from exit_to_user_mode_prepare() with interrupt disabled as the last
  * function before return. Defaults to NOOP.
  */
 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
                           unsigned long ti_work);
 
 #ifndef arch_exit_to_user_mode_prepare
 static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
                           unsigned long ti_work)
 {
 }
 #endif
 
 /**
  * arch_exit_to_user_mode - Architecture specific final work before
  *              exit to user mode.
  *
  * Invoked from exit_to_user_mode() with interrupt disabled as the last
  * function before return. Defaults to NOOP.
  *
  * This needs to be __always_inline because it is non-instrumentable code
  * invoked after context tracking switched to user mode.
  *
  * An architecture implementation must not do anything complex, no locking
  * etc. The main purpose is for speculation mitigations.
  */
 static __always_inline void arch_exit_to_user_mode(void);
 
 #ifndef arch_exit_to_user_mode
 static __always_inline void arch_exit_to_user_mode(void) { }
 #endif
 
 /**
  * arch_do_signal_or_restart -  Architecture specific signal delivery function
  * @regs:   Pointer to currents pt_regs
  * @has_signal: actual signal to handle
  *
  * Invoked from exit_to_user_mode_loop().
  */
 void arch_do_signal_or_restart(struct pt_regs *regs);
 
 /**
  * exit_to_user_mode - Fixup state when exiting to user mode
  *
  * Syscall/interrupt exit enables interrupts, but the kernel state is
  * interrupts disabled when this is invoked. Also tell RCU about it.
  *
  * 1) Trace interrupts on state
  * 2) Invoke context tracking if enabled to adjust RCU state
  * 3) Invoke architecture specific last minute exit code, e.g. speculation
  *    mitigations, etc.: arch_exit_to_user_mode()
  * 4) Tell lockdep that interrupts are enabled
  *
  * Invoked from architecture specific code when syscall_exit_to_user_mode()
  * is not suitable as the last step before returning to userspace. Must be
  * invoked with interrupts disabled and the caller must be
  * non-instrumentable.
  * The caller has to invoke syscall_exit_to_user_mode_work() before this.
  */
 void exit_to_user_mode(void);
 
 /**
  * syscall_exit_to_user_mode_work - Handle work before returning to user mode
  * @regs:   Pointer to currents pt_regs
  *
  * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
  * exit_to_user_mode() to perform the final transition to user mode.
  *
  * Calling convention is the same as for syscall_exit_to_user_mode() and it
  * returns with all work handled and interrupts disabled. The caller must
  * invoke exit_to_user_mode() before actually switching to user mode to
  * make the final state transitions. Interrupts must stay disabled between
  * return from this function and the invocation of exit_to_user_mode().
  */
 void syscall_exit_to_user_mode_work(struct pt_regs *regs);
 
 /**
  * syscall_exit_to_user_mode - Handle work before returning to user mode
  * @regs:   Pointer to currents pt_regs
  *
  * Invoked with interrupts enabled and fully valid regs. Returns with all
  * work handled, interrupts disabled such that the caller can immediately
  * switch to user mode. Called from architecture specific syscall and ret
  * from fork code.
  *
  * The call order is:
  *  1) One-time syscall exit work:
  *  - rseq syscall exit
  *      - audit
  *  - syscall tracing
  *  - ptrace (single stepping)
  *
  *  2) Preparatory work
  *  - Exit to user mode loop (common TIF handling). Invokes
  *    arch_exit_to_user_mode_work() for architecture specific TIF work
  *  - Architecture specific one time work arch_exit_to_user_mode_prepare()
  *  - Address limit and lockdep checks
  *
  *  3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the
  *     functionality in exit_to_user_mode().
  *
  * This is a combination of syscall_exit_to_user_mode_work() (1,2) and
  * exit_to_user_mode(). This function is preferred unless there is a
  * compelling architectural reason to use the separate functions.
  */
 void syscall_exit_to_user_mode(struct pt_regs *regs);
 
 /**
  * irqentry_enter_from_user_mode - Establish state before invoking the irq handler
  * @regs:   Pointer to currents pt_regs
  *
  * Invoked from architecture specific entry code with interrupts disabled.
  * Can only be called when the interrupt entry came from user mode. The
  * calling code must be non-instrumentable.  When the function returns all
  * state is correct and the subsequent functions can be instrumented.
  *
  * The function establishes state (lockdep, RCU (context tracking), tracing)
  */
 void irqentry_enter_from_user_mode(struct pt_regs *regs);
 
 /**
  * irqentry_exit_to_user_mode - Interrupt exit work
  * @regs:   Pointer to current's pt_regs
  *
  * Invoked with interrupts disabled and fully valid regs. Returns with all
  * work handled, interrupts disabled such that the caller can immediately
  * switch to user mode. Called from architecture specific interrupt
  * handling code.
  *
  * The call order is #2 and #3 as described in syscall_exit_to_user_mode().
  * Interrupt exit is not invoking #1 which is the syscall specific one time
  * work.
  */
 void irqentry_exit_to_user_mode(struct pt_regs *regs);
 
 #ifndef irqentry_state
 /**
  * struct irqentry_state - Opaque object for exception state storage
  * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
  *            exit path has to invoke ct_irq_exit().
  * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
  *           lockdep state is restored correctly on exit from nmi.
  *
  * This opaque object is filled in by the irqentry_*_enter() functions and
  * must be passed back into the corresponding irqentry_*_exit() functions
  * when the exception is complete.
  *
  * Callers of irqentry_*_[enter|exit]() must consider this structure opaque
  * and all members private.  Descriptions of the members are provided to aid in
  * the maintenance of the irqentry_*() functions.
  */
 typedef struct irqentry_state {
     union {
         bool    exit_rcu;
         bool    lockdep;
     };
 } irqentry_state_t;
 #endif
 
 /**
  * irqentry_enter - Handle state tracking on ordinary interrupt entries
  * @regs:   Pointer to pt_regs of interrupted context
  *
  * Invokes:
  *  - lockdep irqflag state tracking as low level ASM entry disabled
  *    interrupts.
  *
  *  - Context tracking if the exception hit user mode.
  *
  *  - The hardirq tracer to keep the state consistent as low level ASM
  *    entry disabled interrupts.
  *
  * As a precondition, this requires that the entry came from user mode,
  * idle, or a kernel context in which RCU is watching.
  *
  * For kernel mode entries RCU handling is done conditional. If RCU is
  * watching then the only RCU requirement is to check whether the tick has
  * to be restarted. If RCU is not watching then ct_irq_enter() has to be
  * invoked on entry and ct_irq_exit() on exit.
  *
  * Avoiding the ct_irq_enter/exit() calls is an optimization but also
  * solves the problem of kernel mode pagefaults which can schedule, which
  * is not possible after invoking ct_irq_enter() without undoing it.
  *
  * For user mode entries irqentry_enter_from_user_mode() is invoked to
  * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
  * would not be possible.
  *
  * Returns: An opaque object that must be passed to idtentry_exit()
  */
 irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs);
 
 /**
  * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt
  *
  * Conditional reschedule with additional sanity checks.
  */
 void raw_irqentry_exit_cond_resched(void);
 #ifdef CONFIG_PREEMPT_DYNAMIC
 #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
 #define irqentry_exit_cond_resched_dynamic_enabled  raw_irqentry_exit_cond_resched
 #define irqentry_exit_cond_resched_dynamic_disabled NULL
 DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
 #define irqentry_exit_cond_resched()    static_call(irqentry_exit_cond_resched)()
 #elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
 DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
 void dynamic_irqentry_exit_cond_resched(void);
 #define irqentry_exit_cond_resched()    dynamic_irqentry_exit_cond_resched()
 #endif
 #else /* CONFIG_PREEMPT_DYNAMIC */
 #define irqentry_exit_cond_resched()    raw_irqentry_exit_cond_resched()
 #endif /* CONFIG_PREEMPT_DYNAMIC */
 
 /**
  * irqentry_exit - Handle return from exception that used irqentry_enter()
  * @regs:   Pointer to pt_regs (exception entry regs)
  * @state:  Return value from matching call to irqentry_enter()
  *
  * Depending on the return target (kernel/user) this runs the necessary
  * preemption and work checks if possible and required and returns to
  * the caller with interrupts disabled and no further work pending.
  *
  * This is the last action before returning to the low level ASM code which
  * just needs to return to the appropriate context.
  *
  * Counterpart to irqentry_enter().
  */
 void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
 
 /**
  * irqentry_nmi_enter - Handle NMI entry
  * @regs:   Pointer to currents pt_regs
  *
  * Similar to irqentry_enter() but taking care of the NMI constraints.
  */
 irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
 
 /**
  * irqentry_nmi_exit - Handle return from NMI handling
  * @regs:   Pointer to pt_regs (NMI entry regs)
  * @irq_state:  Return value from matching call to irqentry_nmi_enter()
  *
  * Last action before returning to the low level assembly code.
  *
  * Counterpart to irqentry_nmi_enter().
  */
 void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);
 
 #endif

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