add arm32 syscall conventions

std/os/linux.zig

@@ -17,6 +17,7 @@ pub const is_the_target = builtin.os == .linux;
 pub usingnamespace switch (builtin.arch) {
     .x86_64 => @import("linux/x86_64.zig"),
     .aarch64 => @import("linux/arm64.zig"),
+    .arm => @import("linux/arm-eabi.zig"),
     else => struct {},
 };
 pub usingnamespace @import("bits.zig");

std/os/linux/arm-eabi.zig

@@ -0,0 +1,80 @@
+pub fn syscall0(number: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number)
+    );
+}
+
+pub fn syscall1(number: usize, arg1: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1)
+    );
+}
+
+pub fn syscall2(number: usize, arg1: usize, arg2: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1),
+          [arg2] "{r1}" (arg2)
+    );
+}
+
+pub fn syscall3(number: usize, arg1: usize, arg2: usize, arg3: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1),
+          [arg2] "{r1}" (arg2),
+          [arg3] "{r2}" (arg3)
+    );
+}
+
+pub fn syscall4(number: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1),
+          [arg2] "{r1}" (arg2),
+          [arg3] "{r2}" (arg3),
+          [arg4] "{r3}" (arg4)
+    );
+}
+
+pub fn syscall5(number: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1),
+          [arg2] "{r1}" (arg2),
+          [arg3] "{r2}" (arg3),
+          [arg4] "{r3}" (arg4),
+          [arg5] "{r4}" (arg5)
+    );
+}
+
+pub fn syscall6(
+    number: usize,
+    arg1: usize,
+    arg2: usize,
+    arg3: usize,
+    arg4: usize,
+    arg5: usize,
+    arg6: usize,
+) usize {
+    return asm volatile ("svc #0"
+        : [ret] "={r0}" (-> usize)
+        : [number] "{r7}" (number),
+          [arg1] "{r0}" (arg1),
+          [arg2] "{r1}" (arg2),
+          [arg3] "{r2}" (arg3),
+          [arg4] "{r3}" (arg4),
+          [arg5] "{r4}" (arg5),
+          [arg6] "{r5}" (arg6)
+    );
+}
+
+/// This matches the libc clone function.
+pub extern fn clone(func: extern fn (arg: usize) u8, stack: usize, flags: u32, arg: usize, ptid: *i32, tls: usize, ctid: *i32) usize;