clone

pub fn clone() callconv(.naked) u32

File

Code

pub fn clone() callconv(.naked) u32 {
    // __clone(func, stack, flags, arg, ptid, tls, ctid)
    //         r0,   r1,    r2,    r3,  +0,   +4,  +8
    //
    // syscall(SYS_clone, flags, stack, ptid, tls, ctid)
    //         r7         r0,    r1,    r2,   r3,  r4
    asm volatile (
        \\    stmfd sp!,{r4,r5,r6,r7}
        \\    mov r7,#120 // SYS_clone
        \\    mov r6,r3
        \\    mov r5,r0
        \\    mov r0,r2
        \\    and r1,r1,#-16
        \\    ldr r2,[sp,#16]
        \\    ldr r3,[sp,#20]
        \\    ldr r4,[sp,#24]
        \\    svc 0
        \\    tst r0,r0
        \\    beq 1f
        \\    ldmfd sp!,{r4,r5,r6,r7}
        \\    bx lr
        \\
        \\    // https://github.com/llvm/llvm-project/issues/115891
        \\1:  mov r7, #0
        \\    mov r11, #0
        \\    mov lr, #0
        \\
        \\    mov r0,r6
        \\    bl 3f
        \\    mov r7,#1 // SYS_exit
        \\    svc 0
        \\
        \\3:  bx r5
    );
}