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Filename : sysc_vfork.stp
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# vfork _______________________________________________________
#
# SYSCALL_DEFINE0(vfork)
#

@define _SYSCALL_VFORK_NAME
%(
	name = "vfork"
%)

@define _SYSCALL_VFORK_ARGSTR
%(
	argstr = ""
%)

probe syscall.vfork = dw_syscall.vfork !, nd_syscall.vfork ? {}
probe syscall.vfork.return = dw_syscall.vfork.return !,
                             nd_syscall.vfork.return ? {}

# dw_vfork _____________________________________________________

probe dw_syscall.vfork = kernel.function("sys_vfork").call ?
{
	@_SYSCALL_VFORK_NAME
	@_SYSCALL_VFORK_ARGSTR
}
probe dw_syscall.vfork.return = kernel.function("sys_vfork").return ?
{
	@_SYSCALL_VFORK_NAME
	@SYSC_RETVALSTR($return)
}

# nd_vfork _____________________________________________________

probe nd_syscall.vfork = nd1_syscall.vfork!, nd2_syscall.vfork!, tp_syscall.vfork
  { }

probe nd1_syscall.vfork = kprobe.function("sys_vfork").call ?
{
	@_SYSCALL_VFORK_NAME
	@_SYSCALL_VFORK_ARGSTR
}

/* kernel 4.17+ */
probe nd2_syscall.vfork = kprobe.function(@arch_syscall0_prefix "sys_vfork") ?
{
	@_SYSCALL_VFORK_NAME
	@_SYSCALL_VFORK_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.vfork = kernel.trace("sys_enter") ?
{
	@__syscall_compat_gate(@const("__NR_vfork"), @const("__NR_compat_vfork"))
	@_SYSCALL_VFORK_NAME
	@_SYSCALL_VFORK_ARGSTR
}

probe nd_syscall.vfork.return = nd1_syscall.vfork.return!, nd2_syscall.vfork.return!, tp_syscall.vfork.return
  { }

probe nd1_syscall.vfork.return = kprobe.function("sys_vfork").return ?
{
	@_SYSCALL_VFORK_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 4.17+ */
probe nd2_syscall.vfork.return = kprobe.function(@arch_syscall0_prefix "sys_vfork").return ?
{
	@_SYSCALL_VFORK_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.vfork.return = kernel.trace("sys_exit")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_vfork"), @const("__NR_compat_vfork"))
	@_SYSCALL_VFORK_NAME
	@SYSC_RETVALSTR($ret)
}