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//! 32-bit x86 Linux system calls.
//!
//! There are two forms; `indirect_*` which take a callee, which allow calling
//! through the vDSO when possible, and plain forms, which use the `int 0x80`
//! instruction.
//!
//! Most `rustix` syscalls use the vsyscall mechanism rather than going using
//! `int 0x80` sequences, as vsyscall is much faster.
//!
//! Syscalls made with `int 0x80` preserve the flags register, while syscalls
//! made using vsyscall do not.
#![allow(dead_code)]
use crate::backend::reg::{
ArgReg, FromAsm, RetReg, SyscallNumber, ToAsm, A0, A1, A2, A3, A4, A5, R0,
};
use crate::backend::vdso_wrappers::SyscallType;
use core::arch::asm;
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall0(
callee: SyscallType,
nr: SyscallNumber<'_>,
) -> RetReg<R0> {
let r0;
asm!(
"call {callee}",
callee = in(reg) callee,
inlateout("eax") nr.to_asm() => r0,
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall1(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
) -> RetReg<R0> {
let r0;
asm!(
"call {callee}",
callee = in(reg) callee,
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall1_noreturn(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
) -> ! {
asm!(
"call {callee}",
callee = in(reg) callee,
in("eax") nr.to_asm(),
in("ebx") a0.to_asm(),
options(noreturn)
)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall2(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
) -> RetReg<R0> {
let r0;
asm!(
"call {callee}",
callee = in(reg) callee,
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall3(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
) -> RetReg<R0> {
let r0;
asm!(
"call {callee}",
callee = in(reg) callee,
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall4(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
) -> RetReg<R0> {
let r0;
// a3 should go in esi, but `asm!` won't let us use it as an operand.
// Temporarily swap it into place, and then swap it back afterward.
//
// We hard-code the callee operand to use edi instead of `in(reg)` because
// even though we can't name esi as an operand, the compiler can use esi to
// satisfy `in(reg)`.
asm!(
"xchg esi, {a3}",
"call edi",
"xchg esi, {a3}",
a3 = in(reg) a3.to_asm(),
in("edi") callee,
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall5(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
) -> RetReg<R0> {
let r0;
// Oof. a3 should go in esi, and `asm!` won't let us use that register as
// an operand. And we can't request stack slots. And there are no other
// registers free. Use eax as a temporary pointer to a slice, since it gets
// clobbered as the return value anyway.
asm!(
"push esi",
"push [eax + 0]",
"mov esi, [eax + 4]",
"mov eax, [eax + 8]",
"call [esp]",
"pop esi",
"pop esi",
inout("eax") &[callee as _, a3.to_asm(), nr.to_asm()] => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn indirect_syscall6(
callee: SyscallType,
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
a5: ArgReg<'_, A5>,
) -> RetReg<R0> {
let r0;
// Oof again. a3 should go in esi, and a5 should go in ebp, and `asm!`
// won't let us use either of those registers as operands. And we can't
// request stack slots. And there are no other registers free. Use eax as a
// temporary pointer to a slice, since it gets clobbered as the return
// value anyway.
//
// This is another reason that syscalls should be compiler intrinsics
// rather than inline asm.
asm!(
"push ebp",
"push esi",
"push [eax + 0]",
"mov esi, [eax + 4]",
"mov ebp, [eax + 8]",
"mov eax, [eax + 12]",
"call [esp]",
"pop esi",
"pop esi",
"pop ebp",
inout("eax") &[callee as _, a3.to_asm(), a5.to_asm(), nr.to_asm()] => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall0_readonly(nr: SyscallNumber<'_>) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall1(nr: SyscallNumber<'_>, a0: ArgReg<'_, A0>) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall1_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall1_noreturn(nr: SyscallNumber<'_>, a0: ArgReg<'_, A0>) -> ! {
asm!(
"int $$0x80",
in("eax") nr.to_asm(),
in("ebx") a0.to_asm(),
options(nostack, noreturn)
)
}
#[inline]
pub(in crate::backend) unsafe fn syscall2(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall2_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall3(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall3_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
) -> RetReg<R0> {
let r0;
asm!(
"int $$0x80",
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall4(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
) -> RetReg<R0> {
let r0;
// a3 should go in esi, but `asm!` won't let us use it as an operand.
// Temporarily swap it into place, and then swap it back afterward.
asm!(
"xchg esi, {a3}",
"int $$0x80",
"xchg esi, {a3}",
a3 = in(reg) a3.to_asm(),
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall4_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
) -> RetReg<R0> {
let r0;
asm!(
"xchg esi, {a3}",
"int $$0x80",
"xchg esi, {a3}",
a3 = in(reg) a3.to_asm(),
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall5(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
) -> RetReg<R0> {
let r0;
// As in `syscall4`, use xchg to handle a3. a4 should go in edi, and we can
// use that register as an operand. Unlike in `indirect_syscall5`, we don't
// have a `callee` operand taking up a register, so we have enough
// registers and don't need to use a slice.
asm!(
"xchg esi, {a3}",
"int $$0x80",
"xchg esi, {a3}",
a3 = in(reg) a3.to_asm(),
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
options(nostack, preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall5_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
) -> RetReg<R0> {
let r0;
// See the comments in `syscall5`.
asm!(
"xchg esi, {a3}",
"int $$0x80",
"xchg esi, {a3}",
a3 = in(reg) a3.to_asm(),
inlateout("eax") nr.to_asm() => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
options(nostack, preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall6(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
a5: ArgReg<'_, A5>,
) -> RetReg<R0> {
let r0;
// See the comments in `indirect_syscall6`.
asm!(
"push ebp",
"push esi",
"mov esi, [eax + 0]",
"mov ebp, [eax + 4]",
"mov eax, [eax + 8]",
"int $$0x80",
"pop esi",
"pop ebp",
inout("eax") &[a3.to_asm(), a5.to_asm(), nr.to_asm()] => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
options(preserves_flags)
);
FromAsm::from_asm(r0)
}
#[inline]
pub(in crate::backend) unsafe fn syscall6_readonly(
nr: SyscallNumber<'_>,
a0: ArgReg<'_, A0>,
a1: ArgReg<'_, A1>,
a2: ArgReg<'_, A2>,
a3: ArgReg<'_, A3>,
a4: ArgReg<'_, A4>,
a5: ArgReg<'_, A5>,
) -> RetReg<R0> {
let r0;
// See the comments in `indirect_syscall6`.
asm!(
"push ebp",
"push esi",
"mov esi, [eax + 0]",
"mov ebp, [eax + 4]",
"mov eax, [eax + 8]",
"int $$0x80",
"pop esi",
"pop ebp",
inout("eax") &[a3.to_asm(), a5.to_asm(), nr.to_asm()] => r0,
in("ebx") a0.to_asm(),
in("ecx") a1.to_asm(),
in("edx") a2.to_asm(),
in("edi") a4.to_asm(),
options(preserves_flags, readonly)
);
FromAsm::from_asm(r0)
}