470 строки
16 KiB
C
470 строки
16 KiB
C
/* 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/ptrace.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_enter_from_user_mode - 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_enter_from_user_mode(struct pt_regs *regs);
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#ifndef arch_enter_from_user_mode
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static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {}
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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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* ptrace_report_syscall_entry(), __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);
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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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* - ptrace (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 raw_irqentry_exit_cond_resched(void);
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#ifdef CONFIG_PREEMPT_DYNAMIC
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#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
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#define irqentry_exit_cond_resched_dynamic_enabled raw_irqentry_exit_cond_resched
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#define irqentry_exit_cond_resched_dynamic_disabled NULL
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DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
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#define irqentry_exit_cond_resched() static_call(irqentry_exit_cond_resched)()
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#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
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DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
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void dynamic_irqentry_exit_cond_resched(void);
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#define irqentry_exit_cond_resched() dynamic_irqentry_exit_cond_resched()
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#endif
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#else /* CONFIG_PREEMPT_DYNAMIC */
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#define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched()
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#endif /* CONFIG_PREEMPT_DYNAMIC */
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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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