1#@!#!123s

: / usr / share / systemtap / tapset / linux /
Filename : sysc_writev.stp
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# writev _____________________________________________________
#
# ssize_t sys_writev(unsigned long fd,
#                    const struct iovec __user *vec,
#                    unsigned long vlen)
# ssize_t compat_sys_writev(unsigned long fd,
#                           const struct compat_iovec __user *vec,
#                           unsigned long vlen)
#

@define _SYSCALL_WRITEV_NAME
%(
	name = "writev"
%)

@define _SYSCALL_WRITEV_ARGSTR
%(
	argstr = sprintf("%d, %p, %d", fd, vector_uaddr, count)
%)

@define _SYSCALL_WRITEV_REGARGS
%(
	vector_uaddr = pointer_arg(2)
	count = int_arg(3)
	fd = int_arg(1)
%)

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

# dw_writev _____________________________________________________

probe dw_syscall.writev = kernel.function("compat_sys_writev").call ?,
                       kernel.function("sys_writev").call
{
	@_SYSCALL_WRITEV_NAME
	vector_uaddr = $vec
	count = __int32($vlen)
	# Although the kernel gets an unsigned long fd, on the
	# user-side it is a signed int.  Fix this.
	fd = __int32($fd)
	@_SYSCALL_WRITEV_ARGSTR
}
probe dw_syscall.writev.return = kernel.function("compat_sys_writev").return ?,
                              kernel.function("sys_writev").return
{
	@_SYSCALL_WRITEV_NAME
	@SYSC_RETVALSTR($return)
}

# nd_writev _____________________________________________________

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

probe nd1_syscall.writev = kprobe.function("compat_sys_writev") ?,
                           kprobe.function("sys_writev") ?
{
	@_SYSCALL_WRITEV_NAME
	asmlinkage()
	@_SYSCALL_WRITEV_REGARGS
	@_SYSCALL_WRITEV_ARGSTR
}

/* kernel 4.17+ */
probe nd2_syscall.writev = kprobe.function(@arch_syscall_prefix "compat_sys_writev") ?,
                           kprobe.function(@arch_syscall_prefix "sys_writev") ?
{
	__set_syscall_pt_regs(pointer_arg(1))
	@_SYSCALL_WRITEV_NAME
	@_SYSCALL_WRITEV_REGARGS
	@_SYSCALL_WRITEV_ARGSTR
}

/* kernel 3.5+, but undesirable because it affects all syscalls */
probe tp_syscall.writev = kernel.trace("sys_enter")
{
	__set_syscall_pt_regs($regs)
	@__syscall_compat_gate(@const("__NR_writev"), @const("__NR_compat_writev"))
	@_SYSCALL_WRITEV_NAME
	@_SYSCALL_WRITEV_REGARGS
	@_SYSCALL_WRITEV_ARGSTR
}

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

probe nd1_syscall.writev.return = kprobe.function("compat_sys_writev").return ?,
                                  kprobe.function("sys_writev").return ?
{
	@_SYSCALL_WRITEV_NAME
	@SYSC_RETVALSTR(returnval())
}

/* kernel 4.17+ */
probe nd2_syscall.writev.return = kprobe.function(@arch_syscall_prefix "compat_sys_writev").return ?,
                                  kprobe.function(@arch_syscall_prefix "sys_writev").return ?
{
	@_SYSCALL_WRITEV_NAME
	@SYSC_RETVALSTR(returnval())
}

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