Fix: vmm_map_memory & syscall_nanosleep

[rilysh]

vmm_map_memory can also return NULL, as a result, v_address will be pointed as NULL. For a workaround, handling it with 0 should fix this state.
In syscall_nanosleep, the req param was passed as a constant, and Clang seems to return a warning when compiling. It might not be necessary but I removed req from the const position.

Note: This might require some review since I haven't thoroughly tested the changes yet.

[Milton612]

How have you been able to build this project? I've only been successful in building the kernel and even then I don't know how to build the userspace binaries

[rilysh]

@Milton612 you may want to take a look at https://github.com/ozkl/soso/tree/master/toolchain
Unfortunately, there's no makefile for userspace binaries, for now. You have to manually go through the process of cross compiling them. However, it might be possible to compile the compiler for soso but I'm not sure about that yet.

[Dashbloxx]

This project is extremely broken, even the kernel was hard to build.
A while ago I made this, which uses Soso's kernel and is an attempt to have Soso working again

Edit: I have been able to create a very basic userland program that works on Soso and the fork I've made

[ajh123]

From looking at the existing makefiles I think we need to do the following to make a build:

1. Compile clang, binutils, etc ... using the binutils patch and add the final executables to your $PATH.
2. Compile the kernel with simply just make (use this PR to make compiling successful)
3. Navigate into the userspace folder, and run make all
4. Create the initrd by using the create-initrd.sh script.
5. Create a cd disk image by using the create-cd-image.sh script.

The thing I'm not sure how to do, is step 1.

[ozkl]

info->v_address = (uint32_t)result;

is sufficient here as it is simpler

[ozkl]

instead of removing const from the arg, it is better to introduce void* here:
if (!check_user_access((void*)req))