1 files changed, 115 insertions, 0 deletions
diff --git a/src/bits64/syscall.rs b/src/bits64/syscall.rs
new file mode 100644
index 0000000..c554177
--- /dev/null
+++ b/src/bits64/syscall.rs
@@ -0,0 +1,115 @@
+//! Invokes an OS system-call handler at privilege level 0.
+///
+/// It does so by loading RIP from the IA32_LSTAR MSR (after saving the address of the instruction following SYSCALL into RCX).
+///
+/// "A.2 AMD64 Linux Kernel Conventions" of System V Application Binary Interface AMD64 Architecture Processor Supplement:
+///
+/// * The kernel interface uses %rdi, %rsi, %rdx, %r10, %r8 and %r9.
+/// * A system-call is done via the syscall instruction. The kernel destroys registers %rcx and %r11.
+/// * The number of the syscall has to be passed in register %rax.
+/// * System-calls are limited to six arguments, no argument is passed directly on the stack.
+/// * Returning from the syscall, register %rax contains the result of the system-call. A value in the range between -4095 and -1 indicates an error, it is -errno.
+/// * Only values of class INTEGER or class MEMORY are passed to the kernel.
+///
+/// This code is inspired by the syscall.rs (https://github.com/kmcallister/syscall.rs/) project.
+#[macro_export]
+macro_rules! syscall {
+    ($arg0:expr)
+        => ( $crate::syscall::syscall0($arg0 as u64) );
+
+    ($arg0:expr, $arg1:expr)
+        => ( $crate::syscall::syscall1($arg0 as u64, $arg1 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr)
+        => ( $crate::syscall::syscall2($arg0 as u64, $arg1 as u64, $arg2 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr, $arg3:expr)
+        => ( $crate::syscall::syscall3($arg0 as u64, $arg1 as u64, $arg2 as u64, $arg3 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr)
+        => ( $crate::syscall::syscall4($arg0 as u64, $arg1 as u64, $arg2 as u64, $arg3 as u64, $arg4 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr, $arg5:expr)
+        => ( $crate::syscall::syscall5($arg0 as u64, $arg1 as u64, $arg2 as u64, $arg3 as u64, $arg4 as u64, $arg5 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr, $arg5:expr, $arg6:expr)
+        => ( $crate::syscall::syscall6($arg0 as u64, $arg1 as u64, $arg2 as u64, $arg3 as u64, $arg4 as u64, $arg5 as u64, $arg6 as u64) );
+
+    ($arg0:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr, $arg5:expr, $arg6:expr, $arg7:expr)
+        => ( $crate::syscall::syscall7($arg0 as u64, $arg1 as u64, $arg2 as u64, $arg3 as u64, $arg4 as u64, $arg5 as u64, $arg6 as u64, $arg7 as u64) );
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall0(arg0: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret) : "{rax}" (arg0) : "rcx", "r11", "memory" : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall1(arg0: u64, arg1: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret) : "{rax}" (arg0), "{rdi}" (arg1)
+                   : "rcx", "r11", "memory" : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall2(arg0: u64, arg1: u64, arg2: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret) : "{rax}" (arg0), "{rdi}" (arg1), "{rsi}" (arg2)
+                   : "rcx", "r11", "memory" : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall3(arg0: u64, arg1: u64, arg2: u64, arg3: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret) : "{rax}" (arg0), "{rdi}" (arg1), "{rsi}" (arg2), "{rdx}" (arg3)
+                   : "rcx", "r11", "memory" : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall4(arg0: u64, arg1: u64, arg2: u64, arg3: u64, arg4: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret)
+                   : "{rax}"  (arg0), "{rdi}"  (arg1), "{rsi}"  (arg2), "{rdx}"  (arg3), "{r10}"  (arg4)
+                   : "rcx", "r11", "memory" : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall5(arg0: u64, arg1: u64, arg2: u64, arg3: u64, arg4: u64, arg5: u64) -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret)
+                   : "{rax}" (arg0), "{rdi}" (arg1), "{rsi}" (arg2), "{rdx}" (arg3), "{r10}" (arg4), "{r8}" (arg5)
+                   : "rcx", "r11", "memory"
+                   : "volatile");
+    ret
+}
+
+#[inline(always)]
+#[allow(unused_mut)]
+pub unsafe fn syscall6(arg0: u64,
+                       arg1: u64,
+                       arg2: u64,
+                       arg3: u64,
+                       arg4: u64,
+                       arg5: u64,
+                       arg6: u64)
+                       -> u64 {
+    let mut ret: u64;
+    asm!("syscall" : "={rax}" (ret)
+                   : "{rax}" (arg0), "{rdi}" (arg1), "{rsi}" (arg2), "{rdx}" (arg3),
+                     "{r10}" (arg4), "{r8}" (arg5), "{r9}" (arg6)
+                   : "rcx", "r11", "memory"
+                   : "volatile");
+    ret
+}