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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_ENTRYCOMMON_H
#define __LINUX_ENTRYCOMMON_H
#include <linux/tracehook.h>
#include <linux/syscalls.h>
#include <linux/seccomp.h>
#include <linux/sched.h>
#include <asm/entry-common.h>
/*
* Define dummy _TIF work flags if not defined by the architecture or for
* disabled functionality.
*/
#ifndef _TIF_SYSCALL_EMU
# define _TIF_SYSCALL_EMU (0)
#endif
#ifndef _TIF_SYSCALL_TRACEPOINT
# define _TIF_SYSCALL_TRACEPOINT (0)
#endif
#ifndef _TIF_SECCOMP
# define _TIF_SECCOMP (0)
#endif
#ifndef _TIF_SYSCALL_AUDIT
# define _TIF_SYSCALL_AUDIT (0)
#endif
#ifndef _TIF_PATCH_PENDING
# define _TIF_PATCH_PENDING (0)
#endif
#ifndef _TIF_UPROBE
# define _TIF_UPROBE (0)
#endif
/*
* TIF flags handled in syscall_enter_from_usermode()
*/
#ifndef ARCH_SYSCALL_ENTER_WORK
# define ARCH_SYSCALL_ENTER_WORK (0)
#endif
#define SYSCALL_ENTER_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
_TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \
ARCH_SYSCALL_ENTER_WORK)
/*
* TIF flags handled in syscall_exit_to_user_mode()
*/
#ifndef ARCH_SYSCALL_EXIT_WORK
# define ARCH_SYSCALL_EXIT_WORK (0)
#endif
#define SYSCALL_EXIT_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
/*
* TIF flags handled in exit_to_user_mode_loop()
*/
#ifndef ARCH_EXIT_TO_USER_MODE_WORK
# define ARCH_EXIT_TO_USER_MODE_WORK (0)
#endif
#define EXIT_TO_USER_MODE_WORK \
(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
_TIF_NEED_RESCHED | _TIF_PATCH_PENDING | \
ARCH_EXIT_TO_USER_MODE_WORK)
/**
* arch_check_user_regs - 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_check_user_regs(struct pt_regs *regs);
#ifndef arch_check_user_regs
static __always_inline void arch_check_user_regs(struct pt_regs *regs) {}
#endif
/**
* arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry()
* @regs: Pointer to currents pt_regs
*
* Returns: 0 on success or an error code to skip the syscall.
*
* Defaults to tracehook_report_syscall_entry(). Can be replaced by
* architecture specific code.
*
* Invoked from syscall_enter_from_user_mode()
*/
static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs);
#ifndef arch_syscall_enter_tracehook
static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs)
{
return tracehook_report_syscall_entry(regs);
}
#endif
/**
* syscall_enter_from_user_mode - Check and handle work before invoking
* a syscall
* @regs: Pointer to currents pt_regs
* @syscall: The syscall number
*
* Invoked from architecture specific syscall entry code with interrupts
* disabled. The calling code has to be non-instrumentable. When the
* function returns all state is correct and the subsequent functions can be
* instrumented.
*
* Returns: The original or a modified syscall number
*
* If the returned syscall number is -1 then the syscall should be
* skipped. In this case the caller may invoke syscall_set_error() or
* syscall_set_return_value() first. If neither of those are called and -1
* is returned, then the syscall will fail with ENOSYS.
*
* The following functionality is handled here:
*
* 1) Establish state (lockdep, RCU (context tracking), tracing)
* 2) TIF flag dependent invocations of arch_syscall_enter_tracehook(),
* __secure_computing(), trace_sys_enter()
* 3) Invocation of audit_syscall_entry()
*/
long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
/**
* local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
* @ti_work: Cached TIF flags gathered with interrupts disabled
*
* Defaults to local_irq_enable(). Can be supplied by architecture specific
* code.
*/
static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
#ifndef local_irq_enable_exit_to_user
static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
{
local_irq_enable();
}
#endif
/**
* local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
*
* Defaults to local_irq_disable(). Can be supplied by architecture specific
* code.
*/
static inline void local_irq_disable_exit_to_user(void);
#ifndef local_irq_disable_exit_to_user
static inline void local_irq_disable_exit_to_user(void)
{
local_irq_disable();
}
#endif
/**
* arch_exit_to_user_mode_work - Architecture specific TIF work for exit
* to user mode.
* @regs: Pointer to currents pt_regs
* @ti_work: Cached TIF flags gathered with interrupts disabled
*
* Invoked from exit_to_user_mode_loop() with interrupt enabled
*
* Defaults to NOOP. Can be supplied by architecture specific code.
*/
static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
unsigned long ti_work);
#ifndef arch_exit_to_user_mode_work
static inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
unsigned long ti_work)
{
}
#endif
/**
* arch_exit_to_user_mode_prepare - Architecture specific preparation for
* exit to user mode.
* @regs: Pointer to currents pt_regs
* @ti_work: Cached TIF flags gathered with interrupts disabled
*
* Invoked from exit_to_user_mode_prepare() with interrupt disabled as the last
* function before return. Defaults to NOOP.
*/
static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
unsigned long ti_work);
#ifndef arch_exit_to_user_mode_prepare
static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
unsigned long ti_work)
{
}
#endif
/**
* arch_exit_to_user_mode - Architecture specific final work before
* exit to user mode.
*
* Invoked from exit_to_user_mode() with interrupt disabled as the last
* function before return. Defaults to NOOP.
*
* This needs to be __always_inline because it is non-instrumentable code
* invoked after context tracking switched to user mode.
*
* An architecture implementation must not do anything complex, no locking
* etc. The main purpose is for speculation mitigations.
*/
static __always_inline void arch_exit_to_user_mode(void);
#ifndef arch_exit_to_user_mode
static __always_inline void arch_exit_to_user_mode(void) { }
#endif
/**
* arch_do_signal - Architecture specific signal delivery function
* @regs: Pointer to currents pt_regs
*
* Invoked from exit_to_user_mode_loop().
*/
void arch_do_signal(struct pt_regs *regs);
/**
* arch_syscall_exit_tracehook - Wrapper around tracehook_report_syscall_exit()
* @regs: Pointer to currents pt_regs
* @step: Indicator for single step
*
* Defaults to tracehook_report_syscall_exit(). Can be replaced by
* architecture specific code.
*
* Invoked from syscall_exit_to_user_mode()
*/
static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step);
#ifndef arch_syscall_exit_tracehook
static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step)
{
tracehook_report_syscall_exit(regs, step);
}
#endif
/**
* syscall_exit_to_user_mode - Handle work before returning to user mode
* @regs: Pointer to currents pt_regs
*
* Invoked with interrupts enabled and fully valid regs. Returns with all
* work handled, interrupts disabled such that the caller can immediately
* switch to user mode. Called from architecture specific syscall and ret
* from fork code.
*
* The call order is:
* 1) One-time syscall exit work:
* - rseq syscall exit
* - audit
* - syscall tracing
* - tracehook (single stepping)
*
* 2) Preparatory work
* - Exit to user mode loop (common TIF handling). Invokes
* arch_exit_to_user_mode_work() for architecture specific TIF work
* - Architecture specific one time work arch_exit_to_user_mode_prepare()
* - Address limit and lockdep checks
*
* 3) Final transition (lockdep, tracing, context tracking, RCU). Invokes
* arch_exit_to_user_mode() to handle e.g. speculation mitigations
*/
void syscall_exit_to_user_mode(struct pt_regs *regs);
/**
* irqentry_enter_from_user_mode - Establish state before invoking the irq handler
* @regs: Pointer to currents pt_regs
*
* Invoked from architecture specific entry code with interrupts disabled.
* Can only be called when the interrupt entry came from user mode. The
* calling code must be non-instrumentable. When the function returns all
* state is correct and the subsequent functions can be instrumented.
*
* The function establishes state (lockdep, RCU (context tracking), tracing)
*/
void irqentry_enter_from_user_mode(struct pt_regs *regs);
/**
* irqentry_exit_to_user_mode - Interrupt exit work
* @regs: Pointer to current's pt_regs
*
* Invoked with interrupts disbled 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
typedef struct irqentry_state {
bool exit_rcu;
} 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 rcu_irq_enter() has to be
* invoked on entry and rcu_irq_exit() on exit.
*
* Avoiding the rcu_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 rcu_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 irqentry_exit_cond_resched(void);
/**
* 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 reguired 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);
#endif
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