I am trying to create a simple top utility xv6. To do this, I have created a system call that will allow me to to access the kernel space. I have followed many guides on how to create system calls and my code compiles without issues.
My problem exists when I try running top in qemu. I will get a trap 14 error whenever I try to access my struct array whether it be in kernel or user space.
To break things down a little, I have a top.c file:
...
int main(){
struct uproc table[MAX];//where MAX is defined as 10
if(!getprocs(MAX, table))
printf("YAY");
...
in sysproc.c:
...
int
sys_getprocs(int max, struct uproc table[]){
return gettable(table);
}
and then in procs.c
....
int gettable(struct uproc table[]){
struct uproc u;
struct proc *p;
int i = 0;
aquire(&ptable.lock);
for(p->state.proc; p < &ptable.proc[NPROC];p++){
if(//p->state is valid){
u.state = p->state;
...
table[i] = u;//where I get the trap 14 error
}
}
}
Again, my assumption is that when I pass table around from user to kernel it's getting corrupted, but with that said I'm not sure how I could properly pass it.
