NOVA: drop special utcb handling of main thread

Unify handling of UTCBs. The utcb of the main thread is with commit
ea38aad30e at a fixed location - per convention.
So we can remove all the ugly code to transfer the utcb address during process
creation.

To do so also the UTCB of the main thread of Core must be inside Genode's
thread context area to handle it the same way. Unfortunately the UTCB of the
main thread of Core can't be chosen, it is defined by the kernel.

Possible solutions:
- make virtual address of first thread UTCB configurable in hypervisor
- map the utcb of the first thread inside Core to the desired location

This commit implements the second option.

Kernel patch: make utcb map-able
With the patch the Utcb of the main thread of Core is map-able.

Fixes #374

Noux actually uses the sp variable during thread creation and expects to be
set accordingly. This wasn't the case for the main thread, it was ever set
to the address of the main thread UTCB.

base-nova/patches/del_able_utcb.patch

@@ -0,0 +1,45 @@
+diff --git a/src/ec.cpp b/src/ec.cpp
+index 5d5a66c..a69cfef 100644
+--- a/src/ec.cpp
++++ b/src/ec.cpp
+@@ -64,6 +64,8 @@ Ec::Ec (Pd *own, mword sel, Pd *p, void (*f)(), unsigned c, unsigned e, mword u,
+ 
+         trace (TRACE_SYSCALL, "EC:%p created (PD:%p CPU:%#x UTCB:%#lx ESP:%lx EVT:%#x)", this, p, c, u, s, e);
+ 
++        pd->insert_utcb (u, Buddy::ptr_to_phys(utcb) >> 12);
++
+     } else {
+ 
+         regs.dst_portal = NUM_VMI - 2;
+diff --git a/src/space_mem.cpp b/src/space_mem.cpp
+index 5341836..60e2fdc 100644
+--- a/src/space_mem.cpp
++++ b/src/space_mem.cpp
+@@ -132,12 +132,12 @@ void Space_mem::insert_root (uint64 s, uint64 e, mword a)
+     }
+ }
+ 
+-bool Space_mem::insert_utcb (mword b)
++bool Space_mem::insert_utcb (mword b, mword phys)
+ {
+     if (!b)
+         return true;
+ 
+-    Mdb *mdb = new Mdb (this, 0, b >> PAGE_BITS, 0);
++    Mdb *mdb = new Mdb (this, phys, b >> PAGE_BITS, 0, 0x3);
+ 
+     if (tree_insert (mdb))
+         return true;
+diff --git a/include/space_mem.h b/include/space_mem.h
+index e155dad..1584395 100644
+--- a/include/space_mem.h
++++ b/include/space_mem.h
+@@ -68,7 +68,7 @@ class Space_mem : public Space
+         INIT
+         void insert_root (uint64, uint64, mword = 0x7);
+ 
+-        bool insert_utcb (mword);
++        bool insert_utcb (mword, mword = 0);
+ 
+         void update (Mdb *, mword = 0);
+ 

base-nova/src/base/env/main_thread.cc

@@ -20,13 +20,12 @@
 
 using namespace Genode;
 
-/**
- * Location of the main thread's UTCB, initialized by the startup code
- */
-Nova::mword_t __main_thread_utcb;
-
-
-Native_utcb *main_thread_utcb() { return (Native_utcb *)__main_thread_utcb; }
+Native_utcb *main_thread_utcb()
+{
+	return reinterpret_cast<Native_utcb *>(
+	       Native_config::context_area_virtual_base() +
+	       Native_config::context_area_virtual_size() - Nova::PAGE_SIZE_BYTE);
+}
 
 
 addr_t main_thread_running_semaphore() { return Nova::SM_SEL_EC; }

base-nova/src/core/include/nova_util.h

@@ -56,11 +56,12 @@ static int map_local(Nova::Utcb *utcb, Nova::Crd src_crd, Nova::Crd dst_crd,
 
 	/* establish the mapping via a portal traversal during reply phase */
 	Nova::uint8_t res = Nova::call(echo()->pt_sel());
-	if (res != 0 || utcb->msg_words() != 1 || !utcb->msg[0]) {
-		PERR("Failure - map_local 0x%lx:%lu:%u->0x%lx:%lu:%u - call result=%x utcb=%x:%lx !!!",
+	if (res != Nova::NOVA_OK || utcb->msg_words() != 1 || !utcb->msg[0]) {
+		PERR("Failure - map_local 0x%lx:%lu:%u->0x%lx:%lu:%u - call result=%x"
+		     " utcb=%x:%lx !!! %p %u",
 		     src_crd.addr(), src_crd.order(), src_crd.type(),
 		     dst_crd.addr(), dst_crd.order(), dst_crd.type(),
-		     res, utcb->msg_words(), utcb->msg[0]);
+		     res, utcb->msg_words(), utcb->msg[0], utcb, kern_pd);
 		return res > 0 ? res : -1;
 	}
 	/* clear receive window */

base-nova/src/core/platform.cc

@@ -34,6 +34,7 @@ using namespace Nova;
 
 enum { verbose_boot_info = true };
 
+Native_utcb *main_thread_utcb();
 
 /**
  * Initial value of esp register, saved by the crt0 startup code
@@ -52,7 +53,7 @@ extern int __first_free_cap_selector;
 /**
  * Pointer to the UTCB of the main thread
  */
-extern Utcb *__main_thread_utcb;
+Utcb *__main_thread_utcb;
 
 
 /**
@@ -384,6 +385,13 @@ Platform::Platform() :
 	_irq_alloc.add_range(0, hip->sel_gsi - 1);
 	_gsi_base_sel = (hip->mem_desc_offset - hip->cpu_desc_offset) / hip->cpu_desc_size;
 
+	/* remap main utcb to default utbc address */
+	if (map_local(__main_thread_utcb, (addr_t)__main_thread_utcb,
+	              (addr_t)main_thread_utcb(), 1)) {
+		PERR("could not remap main threads utcb");
+		nova_die();
+	}
+
 	if (verbose_boot_info) {
 		printf(":virt_alloc: "); _core_mem_alloc.virt_alloc()->raw()->dump_addr_tree();
 		printf(":phys_alloc: "); _core_mem_alloc.phys_alloc()->raw()->dump_addr_tree();

base-nova/src/core/platform_thread.cc

@@ -55,12 +55,10 @@ int Platform_thread::start(void *ip, void *sp)
 		return -2;
 	}
 
-	_pager->initial_eip((addr_t)ip);
 	if (!_is_main_thread) {
 		addr_t initial_sp = reinterpret_cast<addr_t>(sp);
 		addr_t utcb       = _is_vcpu ? 0 : round_page(initial_sp);
 
-		_pager->initial_esp(initial_sp);
 		if (_sel_exc_base == Native_thread::INVALID_INDEX) {
 			PERR("exception base not specified");
 			return -3;
@@ -72,12 +70,10 @@ int Platform_thread::start(void *ip, void *sp)
 		 * SM_SEL_EC_CLIENT and can be later on requested by the thread
 		 * the same way as STARTUP and PAGEFAULT portal.
 		 */
-		uint8_t res = Nova::create_sm(_pager->exc_pt_sel() +
-		                              SM_SEL_EC_CLIENT,
-		                              _pd->pd_sel(), 0);
+		addr_t  sm  = _pager->exc_pt_sel() + SM_SEL_EC_CLIENT;
+		uint8_t res = Nova::create_sm(sm, _pd->pd_sel(), 0);
 		if (res != Nova::NOVA_OK) {
-			PERR("creation of semaphore for new thread failed %u",
-			     res);
+			PERR("creation of semaphore for new thread failed %u", res);
 			return -4;
 		}
 
@@ -86,12 +82,17 @@ int Platform_thread::start(void *ip, void *sp)
 
 		res = create_ec(_sel_ec(), _pd->pd_sel(), _cpu_no, utcb,
 		                initial_sp, _sel_exc_base, thread_global);
-		if (res)
+		if (res != Nova::NOVA_OK) {
+			revoke(Obj_crd(sm, 0));
 			PERR("creation of new thread failed %u", res);
+			return -5;
+		}
 
+		_pager->initial_eip((addr_t)ip);
+		_pager->initial_esp(initial_sp);
 		_pager->client_set_ec(_sel_ec());
 
-		return res ? -5 : 0;
+		return 0;
 	}
 
 	if (_sel_exc_base != Native_thread::INVALID_INDEX) {
@@ -107,8 +108,6 @@ int Platform_thread::start(void *ip, void *sp)
 	                 Native_config::context_area_virtual_size() -
 	                 get_page_size();
 
-	_pager->initial_esp(pd_utcb + get_page_size());
-
 	_sel_exc_base = cap_selector_allocator()->alloc(NUM_INITIAL_PT_LOG2);
 
 	addr_t pd_core_sel  = Platform_pd::pd_core_sel();
@@ -176,7 +175,7 @@ int Platform_thread::start(void *ip, void *sp)
 
 	/* create task */
 	res = create_pd(pd_sel, pd_core_sel, initial_pts);
-	if (res) {
+	if (res != NOVA_OK) {
 		PERR("create_pd returned %d", res);
 		goto cleanup_pd;
 	}
@@ -185,7 +184,7 @@ int Platform_thread::start(void *ip, void *sp)
 	enum { THREAD_GLOBAL = true };
 	res = create_ec(_sel_ec(), pd_sel, _cpu_no, pd_utcb, 0, 0,
 	                THREAD_GLOBAL);
-	if (res) {
+	if (res != NOVA_OK) {
 		PERR("create_ec returned %d", res);
 		goto cleanup_pd;
 	}
@@ -196,16 +195,20 @@ int Platform_thread::start(void *ip, void *sp)
 	 */
 	_pd->assign_pd(pd_sel);
 	_pager->client_set_ec(_sel_ec());
+	_pager->initial_eip((addr_t)ip);
+	_pager->initial_esp((addr_t)sp);
 
 	/* Let the thread run */
 	res = create_sc(_sel_sc(), pd_sel, _sel_ec(), Qpd());
-	if (res) {
+	if (res != NOVA_OK) {
 		/**
 		 * Reset pd cap since thread got not running and pd cap will
 		 * be revoked during cleanup.
 		 */
 		_pd->assign_pd(Native_thread::INVALID_INDEX);
 		_pager->client_set_ec(Native_thread::INVALID_INDEX);
+		_pager->initial_eip(0);
+		_pager->initial_esp(0);
 
 		PERR("create_sc returned %d", res);
 		goto cleanup_ec;

base-nova/src/platform/_main_helper.h

@@ -18,11 +18,6 @@
 #include <nova/syscalls.h>
 #include <base/stdint.h>
 
-/**
- * Location of the main thread's UTCB, initialized by the startup code
- */
-extern Nova::mword_t __main_thread_utcb;
-
 /**
  * Initial value of esp register, saved by the crt0 startup code
  *
@@ -37,9 +32,6 @@ extern int __first_free_cap_selector;
 
 static void main_thread_bootstrap()
 {
-	/* register UTCB of main thread */
-	__main_thread_utcb = __initial_sp - Nova::PAGE_SIZE_BYTE;
-
 	/* register start of usable capability range */
 	enum { FIRST_FREE_PORTAL = 0x1000 };
 

os/src/lib/ldso/symbol.map

@@ -76,9 +76,7 @@
 		l4_atomic_cmpxchg;
 
 		/* Nova */
-		__main_thread_utcb;
 		__first_free_cap_selector;
-		__local_pd_sel;
 
 		extern "C++" {
 			main_thread_utcb*;