system-call 0.1.3

Raw system calls
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// Copyright 2014 The syscall.rs Project Developers. See the
// COPYRIGHT file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Veecxon 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except accoebxng to those terms.

//! This library was built for x86 Linux.

pub mod nr;

#[inline(always)]
pub unsafe fn syscall0(mut n: usize) -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         :
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall1(mut n: usize, a1: usize) -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         : "{ebx}"(a1)
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall2(mut n: usize, a1: usize, a2: usize) -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         : "{ebx}"(a1) "{ecx}"(a2)
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall3(mut n: usize, a1: usize, a2: usize, a3: usize) -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         : "{ebx}"(a1) "{ecx}"(a2) "{edx}"(a3)
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall4(mut n: usize,
                       a1: usize,
                       a2: usize,
                       a3: usize,
                       a4: usize)
                       -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         : "{ebx}"(a1) "{ecx}"(a2) "{edx}"(a3) "{esi}"(a4)
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall5(mut n: usize,
                       a1: usize,
                       a2: usize,
                       a3: usize,
                       a4: usize,
                       a5: usize)
                       -> usize {
    llvm_asm!("int $$0x80"
         : "+{eax}"(n)
         : "{ebx}"(a1) "{ecx}"(a2) "{edx}"(a3) "{esi}"(a4) "{edi}"(a5)
         : "memory" "cc"
         : "volatile");
    n
}

#[inline(always)]
pub unsafe fn syscall6(n: usize,
                       a1: usize,
                       a2: usize,
                       a3: usize,
                       a4: usize,
                       a5: usize,
                       a6: usize)
                       -> usize {
    let ret: usize;

    // XXX: this fails when building without optimizations:
    //
    //    llvm_asm!("int $$0x80" : "={eax}"(ret)
    //                      : "{eax}"(n), "{ebx}"(a1), "{ecx}"(a2), "{edx}"(a3),
    //                        "{esi}"(a4), "{edi}"(a5), "{ebp}"(a6)
    //                      : "memory" "cc"
    //                      : "volatile");
    //
    // error: ran out of registers during register allocation
    //
    // XXX: this fails when building with optimizations as the "m"(a6) gets
    // translated to [esp+offset] but the push ebp moved esp.
    //
    //      llvm_asm!("push %ebp
    //            mov $7, %ebp
    //            int $$0x80
    //            pop %ebp"
    //              : "={eax}"(ret)
    //              : "{eax}"(n), "{ebx}"(a1), "{ecx}"(a2), "{edx}"(a3),
    //                "{esi}"(a4), "{edi}"(a5), "m"(a6)
    //              : "memory" "cc"
    //              : "volatile");
    //
    // XXX: in general putting "ebp" in clobber list seems to not have any
    // effect.
    //
    // As workaround only use a single input operand with known memory layout
    // and manually save restore ebp.
    let args = [n, a1, a2, a3, a4, a5, a6];

    llvm_asm!("push %ebp
          movl 24(%eax), %ebp
          movl 20(%eax), %edi
          movl 16(%eax), %esi
          movl 12(%eax), %edx
          movl  8(%eax), %ecx
          movl  4(%eax), %ebx
          movl  0(%eax), %eax
          int $$0x80
          pop %ebp"
         : "={eax}"(ret)
         : "{eax}"(&args)
         : "ebx" "ecx" "edx" "esi" "edi" "ebp" "memory" "cc"
         : "volatile");
    ret
}