diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/entry-common.h | 382 | ||||
| -rw-r--r-- | include/linux/irq-entry-common.h | 389 |
2 files changed, 390 insertions, 381 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index f94f3fdf15fc..7177436f0f9e 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -2,28 +2,16 @@ #ifndef __LINUX_ENTRYCOMMON_H #define __LINUX_ENTRYCOMMON_H -#include <linux/static_call_types.h> +#include <linux/irq-entry-common.h> #include <linux/ptrace.h> -#include <linux/syscalls.h> #include <linux/seccomp.h> #include <linux/sched.h> -#include <linux/context_tracking.h> #include <linux/livepatch.h> #include <linux/resume_user_mode.h> -#include <linux/tick.h> -#include <linux/kmsan.h> #include <asm/entry-common.h> #include <asm/syscall.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 @@ -56,69 +44,6 @@ 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_NEED_RESCHED_LAZY | \ - _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(). - */ -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() != CT_STATE_USER); - user_exit_irqoff(); - - instrumentation_begin(); - kmsan_unpoison_entry_regs(regs); - trace_hardirqs_off_finish(); - instrumentation_end(); -} - /** * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts * @regs: Pointer to currents pt_regs @@ -204,170 +129,6 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l } /** - * 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 - * - * Invoked from exit_to_user_mode_loop(). - */ -void arch_do_signal_or_restart(struct pt_regs *regs); - -/** - * exit_to_user_mode_loop - do any pending work before leaving to user space - */ -unsigned long exit_to_user_mode_loop(struct pt_regs *regs, - unsigned long ti_work); - -/** - * exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required - * @regs: Pointer to pt_regs on entry stack - * - * 1) check that interrupts are disabled - * 2) call tick_nohz_user_enter_prepare() - * 3) call exit_to_user_mode_loop() if any flags from - * EXIT_TO_USER_MODE_WORK are set - * 4) check that interrupts are still disabled - */ -static __always_inline 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 kernel state is sane for a return to userspace */ - kmap_assert_nomap(); - lockdep_assert_irqs_disabled(); - lockdep_sys_exit(); -} - -/** - * 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. - */ -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); -} - -/** * syscall_exit_work - Handle work before returning to user mode * @regs: Pointer to current pt_regs * @work: Current thread syscall work @@ -451,145 +212,4 @@ static __always_inline void syscall_exit_to_user_mode(struct pt_regs *regs) exit_to_user_mode(); } -/** - * 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 diff --git a/include/linux/irq-entry-common.h b/include/linux/irq-entry-common.h new file mode 100644 index 000000000000..8af374331900 --- /dev/null +++ b/include/linux/irq-entry-common.h @@ -0,0 +1,389 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_IRQENTRYCOMMON_H +#define __LINUX_IRQENTRYCOMMON_H + +#include <linux/static_call_types.h> +#include <linux/syscalls.h> +#include <linux/context_tracking.h> +#include <linux/tick.h> +#include <linux/kmsan.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 + +/* + * 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_NEED_RESCHED_LAZY | \ + _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(). + */ +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() != CT_STATE_USER); + user_exit_irqoff(); + + instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); + trace_hardirqs_off_finish(); + instrumentation_end(); +} + +/** + * 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 + * + * Invoked from exit_to_user_mode_loop(). + */ +void arch_do_signal_or_restart(struct pt_regs *regs); + +/** + * exit_to_user_mode_loop - do any pending work before leaving to user space + */ +unsigned long exit_to_user_mode_loop(struct pt_regs *regs, + unsigned long ti_work); + +/** + * exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required + * @regs: Pointer to pt_regs on entry stack + * + * 1) check that interrupts are disabled + * 2) call tick_nohz_user_enter_prepare() + * 3) call exit_to_user_mode_loop() if any flags from + * EXIT_TO_USER_MODE_WORK are set + * 4) check that interrupts are still disabled + */ +static __always_inline 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 kernel state is sane for a return to userspace */ + kmap_assert_nomap(); + lockdep_assert_irqs_disabled(); + lockdep_sys_exit(); +} + +/** + * 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. + */ +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); +} + +/** + * 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 |