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