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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_ENTRYCOMMON_H
#define __LINUX_ENTRYCOMMON_H
#include <linux/irq-entry-common.h>
#include <linux/ptrace.h>
#include <linux/seccomp.h>
#include <linux/sched.h>
#include <linux/livepatch.h>
#include <linux/resume_user_mode.h>
#include <asm/entry-common.h>
#include <asm/syscall.h>
#ifndef _TIF_UPROBE
# define _TIF_UPROBE (0)
#endif
/*
* SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
*/
#ifndef ARCH_SYSCALL_WORK_ENTER
# define ARCH_SYSCALL_WORK_ENTER (0)
#endif
/*
* SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
*/
#ifndef ARCH_SYSCALL_WORK_EXIT
# define ARCH_SYSCALL_WORK_EXIT (0)
#endif
#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE | \
SYSCALL_WORK_SYSCALL_EMU | \
SYSCALL_WORK_SYSCALL_AUDIT | \
SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
ARCH_SYSCALL_WORK_ENTER)
#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE | \
SYSCALL_WORK_SYSCALL_AUDIT | \
SYSCALL_WORK_SYSCALL_USER_DISPATCH | \
SYSCALL_WORK_SYSCALL_EXIT_TRAP | \
ARCH_SYSCALL_WORK_EXIT)
/**
* syscall_enter_from_user_mode_prepare - Establish state and enable interrupts
* @regs: Pointer to currents pt_regs
*
* Invoked from architecture specific syscall entry code with interrupts
* disabled. The calling code has to be non-instrumentable. When the
* function returns all state is correct, interrupts are enabled and the
* subsequent functions can be instrumented.
*
* This handles lockdep, RCU (context tracking) and tracing state, i.e.
* the functionality provided by enter_from_user_mode().
*
* This is invoked when there is extra architecture specific functionality
* to be done between establishing state and handling user mode entry work.
*/
void syscall_enter_from_user_mode_prepare(struct pt_regs *regs);
long syscall_trace_enter(struct pt_regs *regs, long syscall,
unsigned long work);
/**
* syscall_enter_from_user_mode_work - Check and handle work before invoking
* a syscall
* @regs: Pointer to currents pt_regs
* @syscall: The syscall number
*
* Invoked from architecture specific syscall entry code with interrupts
* enabled after invoking syscall_enter_from_user_mode_prepare() and extra
* architecture specific work.
*
* Returns: The original or a modified syscall number
*
* If the returned syscall number is -1 then the syscall should be
* skipped. In this case the caller may invoke syscall_set_error() or
* syscall_set_return_value() first. If neither of those are called and -1
* is returned, then the syscall will fail with ENOSYS.
*
* It handles the following work items:
*
* 1) syscall_work flag dependent invocations of
* ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter()
* 2) Invocation of audit_syscall_entry()
*/
static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
if (work & SYSCALL_WORK_ENTER)
syscall = syscall_trace_enter(regs, syscall, work);
return syscall;
}
/**
* syscall_enter_from_user_mode - Establish state and check and handle work
* before invoking a syscall
* @regs: Pointer to currents pt_regs
* @syscall: The syscall number
*
* Invoked from architecture specific syscall entry code with interrupts
* disabled. The calling code has to be non-instrumentable. When the
* function returns all state is correct, interrupts are enabled and the
* subsequent functions can be instrumented.
*
* This is combination of syscall_enter_from_user_mode_prepare() and
* syscall_enter_from_user_mode_work().
*
* Returns: The original or a modified syscall number. See
* syscall_enter_from_user_mode_work() for further explanation.
*/
static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
{
long ret;
enter_from_user_mode(regs);
instrumentation_begin();
local_irq_enable();
ret = syscall_enter_from_user_mode_work(regs, syscall);
instrumentation_end();
return ret;
}
/**
* syscall_exit_work - Handle work before returning to user mode
* @regs: Pointer to current pt_regs
* @work: Current thread syscall work
*
* Do one-time syscall specific work.
*/
void syscall_exit_work(struct pt_regs *regs, unsigned long work);
/**
* syscall_exit_to_user_mode_work - Handle work before returning to user mode
* @regs: Pointer to currents pt_regs
*
* Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
* exit_to_user_mode() to perform the final transition to user mode.
*
* Calling convention is the same as for syscall_exit_to_user_mode() and it
* returns with all work handled and interrupts disabled. The caller must
* invoke exit_to_user_mode() before actually switching to user mode to
* make the final state transitions. Interrupts must stay disabled between
* return from this function and the invocation of exit_to_user_mode().
*/
static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
{
unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
unsigned long nr = syscall_get_nr(current, regs);
CT_WARN_ON(ct_state() != CT_STATE_KERNEL);
if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
local_irq_enable();
}
rseq_syscall(regs);
/*
* Do one-time syscall specific work. If these work items are
* enabled, we want to run them exactly once per syscall exit with
* interrupts enabled.
*/
if (unlikely(work & SYSCALL_WORK_EXIT))
syscall_exit_work(regs, work);
local_irq_disable_exit_to_user();
exit_to_user_mode_prepare(regs);
}
/**
* syscall_exit_to_user_mode - Handle work before returning to user mode
* @regs: Pointer to currents pt_regs
*
* Invoked with interrupts enabled and fully valid regs. Returns with all
* work handled, interrupts disabled such that the caller can immediately
* switch to user mode. Called from architecture specific syscall and ret
* from fork code.
*
* The call order is:
* 1) One-time syscall exit work:
* - rseq syscall exit
* - audit
* - syscall tracing
* - ptrace (single stepping)
*
* 2) Preparatory work
* - Exit to user mode loop (common TIF handling). Invokes
* arch_exit_to_user_mode_work() for architecture specific TIF work
* - Architecture specific one time work arch_exit_to_user_mode_prepare()
* - Address limit and lockdep checks
*
* 3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the
* functionality in exit_to_user_mode().
*
* This is a combination of syscall_exit_to_user_mode_work() (1,2) and
* exit_to_user_mode(). This function is preferred unless there is a
* compelling architectural reason to use the separate functions.
*/
static __always_inline void syscall_exit_to_user_mode(struct pt_regs *regs)
{
instrumentation_begin();
syscall_exit_to_user_mode_work(regs);
instrumentation_end();
exit_to_user_mode();
}
#endif
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