syscalls: implement sysctl and add process listing

kernel-src/sys/syscalls/sysctl.c

@@ -0,0 +1,28 @@
+#include <kernel/syscalls.h>
+#include <kernel/sysctl.h>
+#include <arch/mmu.h>
+
+syscallret_t syscall_sysctl(context_t *, int *namep, size_t name_len, void *oldp, size_t *old_lenp, void *newp, size_t new_len) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	if (name_len > SYS_CTL_NAME_MAX) {
+		ret.errno = EINVAL;
+		return ret;
+	}
+
+	if (!IS_USER_ADDRESS(namep) || !IS_USER_ADDRESS(oldp) || !IS_USER_ADDRESS(old_lenp) || !IS_USER_ADDRESS(newp)) {
+		ret.errno = EFAULT;
+		return ret;
+	}
+
+	int name[name_len];
+	ret.errno = usercopy_fromuser(name, namep, sizeof(name));
+	if (ret.errno)
+		return ret;
+
+	ret.errno = sysctl(name, name_len, oldp, old_lenp, newp, new_len);
+	ret.ret = ret.errno ? -1 : 0;
+	return ret;
+}