[kernel] Remove process & thread self-handles

For the coming switch to cap/handle ref-counting being the main lifetime
determiner of objects, get rid of self handles for threads and processes
to avoid circular references. Instead, passing 0 to syscalls expecting a
thread or process handle signifies "this process/thread".

definitions/objects/thread.def

@@ -7,7 +7,7 @@ object thread : object {
     ]
 
     method create [constructor] {
-        param process ref process [cap:create_thread]
+        param process ref process [optional cap:create_thread]
         param stack_top address
         param entrypoint address
         param arg0 uint64

definitions/objects/vma.def

@@ -22,12 +22,12 @@ object vma : object {
     }
 
     method map [cap:map] {
-        param process ref process
+        param process ref process [optional]
         param address address
     }
 
     method unmap [cap:unmap] {
-        param process ref process
+        param process ref process [optional]
     }
 
     method resize [cap:resize] {

src/kernel/objects/process.cpp

@@ -24,8 +24,6 @@ process::process() :
     kobject {kobject::type::process},
     m_state {state::running}
 {
-    m_self_handle = g_cap_table.create(this, process::self_caps);
-    add_handle(m_self_handle);
 }
 
 // The "kernel process"-only constructor
@@ -71,28 +69,6 @@ process::exit(int32_t code)
         current.exit();
 }
 
-void
-process::update()
-{
-    util::scoped_lock lock {m_threads_lock};
-
-    kassert(false, "process::update used!");
-    kassert(m_threads.count() > 0, "process::update with zero threads!");
-
-    size_t i = 0;
-    while (i < m_threads.count()) {
-        thread *th = m_threads[i];
-        if (th->has_state(thread::state::exited)) {
-            m_threads.remove_swap_at(i);
-            continue;
-        }
-        i++;
-    }
-
-    if (m_threads.count() == 0)
-        exit(-1);
-}
-
 thread *
 process::create_thread(uintptr_t rsp3, uint8_t priority)
 {

src/kernel/objects/process.h

@@ -20,9 +20,6 @@ public:
     /// Capabilities on a newly constructed process handle
     static constexpr j6_cap_t creation_caps = j6_cap_process_all;
 
-    /// Capabilities on a process to itself
-    static constexpr j6_cap_t self_caps = j6_cap_process_all;
-
     /// Top of memory area where thread stacks are allocated
     static constexpr uintptr_t stacks_top = 0x0000800000000000;
 
@@ -47,9 +44,6 @@ public:
     /// \arg code   The return code to exit with.
     void exit(int32_t code);
 
-    /// Update internal bookkeeping about threads.
-    void update();
-
     /// Get the process' virtual memory space
     vm_space & space() { return m_space; }
 
@@ -105,7 +99,6 @@ private:
     // This constructor is called by create_kernel_process
     process(page_table *kpml4);
 
-    j6_handle_t m_self_handle;
     int32_t m_return_code;
 
     vm_space m_space;

src/kernel/objects/thread.cpp

@@ -32,8 +32,6 @@ thread::thread(process &parent, uint8_t pri, uintptr_t rsp0) :
         m_tcb.rsp0 = rsp0;
 
     m_creator = current_cpu().thread;
-    m_self_handle = g_cap_table.create(this, thread::parent_caps);
-    parent.add_handle(m_self_handle);
 }
 
 thread::~thread()

src/kernel/objects/thread.h

@@ -57,9 +57,6 @@ public:
     /// Capabilities on a newly constructed thread handle
     static constexpr j6_cap_t creation_caps = j6_cap_thread_all;
 
-    /// Capabilities the parent process gets on new thread handles
-    static constexpr j6_cap_t parent_caps = j6_cap_thread_all;
-
     static constexpr kobject::type type = kobject::type::thread;
 
     enum class state : uint8_t {
@@ -168,9 +165,6 @@ public:
             uintptr_t rip0 = 0,
             uint64_t flags = 0);
 
-    /// Get the handle representing this thread to its process
-    j6_handle_t self_handle() const { return m_self_handle; }
-
     /// Create the kernel idle thread
     /// \arg kernel The process object that owns kernel tasks
     /// \arg rsp    The existing stack for the idle thread
@@ -208,7 +202,6 @@ private:
     message_data m_message_data;
 
     wait_queue m_join_queue;
-    j6_handle_t m_self_handle;
 };
 
 } // namespace obj

src/kernel/syscall_verify.cpp.cog

@@ -133,7 +133,7 @@ for id, scope, method in syscalls.methods:
                     param.type.object.cname,
                     arg,
                     get_caps(param.options, param.type.object),
-                    param.optional))
+                    param.optional != "required"))
 
                 if needs_obj:
                     objparams.append((type, arg))
@@ -149,7 +149,7 @@ for id, scope, method in syscalls.methods:
                 f"obj::{param.type.object.cname}",
                 arg,
                 get_caps(param.options, param.type.object,
-                param.optional)))
+                param.optional != "required")))
 
         if param.refparam:
             subs = param.type.c_names(param.options)

src/kernel/syscalls/thread.cpp

@@ -17,9 +17,14 @@ thread_create(j6_handle_t *self, process *proc, uintptr_t stack_top, uintptr_t e
     thread &parent_th = thread::current();
     process &parent_pr = parent_th.parent();
 
+    if (!proc)
+        proc = &parent_pr;
+
     thread *child = proc->create_thread(stack_top);
     child->add_thunk_user(entrypoint, arg0, arg1);
-    *self = child->self_handle();
+
+    *self = g_cap_table.create(child, thread::creation_caps);
+
     child->set_state(thread::state::ready);
 
     log::verbose(logs::task, "Thread <%02lx:%02lx> spawned new thread <%02lx:%02lx>",

src/kernel/syscalls/vm_area.cpp

@@ -31,14 +31,16 @@ vma_create_map(j6_handle_t *self, size_t size, uintptr_t base, uint32_t flags)
 j6_status_t
 vma_map(vm_area *self, process *proc, uintptr_t base)
 {
-    proc->space().add(base, self);
+    vm_space &space = proc ? proc->space() : process::current().space();
+    space.add(base, self);
     return j6_status_ok;
 }
 
 j6_status_t
 vma_unmap(vm_area *self, process *proc)
 {
-    proc->space().remove(self);
+    vm_space &space = proc ? proc->space() : process::current().space();
+    space.remove(self);
     return j6_status_ok;
 }
 

src/libraries/j6/init.cpp

@@ -9,11 +9,10 @@
 #include <j6/syscalls.h>
 #include <j6/types.h>
 
-j6_handle_t __handle_self;
-
 namespace {
     constexpr size_t static_arr_count = 8;
     j6_handle_descriptor handle_array[static_arr_count];
+    j6_init_args init_args;
 } // namespace
 
 j6_handle_t
@@ -37,10 +36,12 @@ j6_find_first_handle(j6_object_type obj_type)
     return j6_handle_invalid;
 }
 
-extern "C" void
-__init_libj6(uint64_t *rsp)
+extern "C" j6_init_args *
+__init_libj6(uint64_t arg0, uint64_t arg1)
 {
-    __handle_self = j6_find_first_handle(j6_object_type_process);
+    init_args.args[0] = arg0;
+    init_args.args[1] = arg1;
+    return &init_args;
 }
 
 #endif // __j6kernel

src/libraries/j6/j6/init.h

@@ -8,6 +8,11 @@
 extern "C" {
 #endif
 
+struct j6_init_args
+{
+    uint64_t args[2];
+};
+
 /// Find the first handle of the given type held by this process
 j6_handle_t j6_find_first_handle(j6_object_type obj_type);
 

src/libraries/libc/arch/amd64/crt/crt0.s

@@ -5,15 +5,21 @@ extern __init_libc
 
 global _start:function (_start.end - _start)
 _start:
-	mov rbp, rsp
-	mov rdi, rsp
-	call __init_libj6
-	call __init_libc
+    push 0              ; Add null frame
+    push 0
+    mov rbp, rsp
 
-	pop rdi
-	mov rsi, rsp
-	call main
+    call __init_libj6
+    mov rbx, rax
 
-	mov rdi, rax
-	call exit
+    call __init_libc
+
+    pop rdi
+    mov rsi, rsp
+    mov rdx, 0    ; TODO: actually parse stack for argc, argv, envp
+    mov rcx, rbx
+    call main
+
+    mov rdi, rax
+    call exit
 .end:

src/libraries/libc/arch/amd64/crt/init.cpp

@@ -11,11 +11,14 @@ namespace {
 void
 run_ctor_list(cb *array, cb *end)
 {
+    if (!array || !end)
+        return;
+
     size_t i = 0;
     while (true) {
         const cb &ctor = array[i++];
         if (&ctor == end) return;
-        ctor();
+        if (ctor) ctor();
     }
 }