base: hide internals of the Thread API

This patch moves details about the stack allocation and organization
the base-internal headers. Thereby, I replaced the notion of "thread
contexts" by "stacks" as this term is much more intuitive. The fact that
we place thread-specific information at the bottom of the stack is not
worth introducing new terminology.

Issue #1832

repos/base-linux/src/base/env/rm_session_mmap.cc

@@ -8,7 +8,7 @@
  * dataspaces and 2) get the kernel to manage VM regions as we intent.
  *
  * The kernel sets up mappings for the binary on execve(), which are text and
- * data segments, the context area and special regions (stack, vdso, vsyscall).
+ * data segments, the stack area and special regions (stack, vdso, vsyscall).
  * Later mappings are done by the Genode program itself, which knows nothing
  * about these initial mappings. Therefore, most mmap() operations are _soft_
  * to detect region conflicts with existing mappings or let the kernel find
@@ -17,10 +17,10 @@
  * but not populated dataspaces are "holes" in the Linux VM space represented
  * by PROT_NONE mappings (see _reserve_local()).
  *
- * The context area is a managed dataspace as on other platforms, which is
+ * The stack area is a managed dataspace as on other platforms, which is
  * created and attached during program launch. The managed dataspace replaces
  * the inital reserved area, which is therefore flushed beforehand. Hybrid
- * programs have no context area.
+ * programs have no stack area.
  *
  * Note, we do not support nesting of managed dataspaces.
  */
@@ -40,7 +40,7 @@
 /* base-internal includes */
 #include <base/internal/local_capability.h>
 #include <base/internal/platform_env.h>
-#include <base/internal/context_area.h>
+#include <base/internal/stack_area.h>
 
 using namespace Genode;
 
@@ -58,13 +58,13 @@ addr_t Platform_env_base::Rm_session_mmap::_reserve_local(bool           use_loc
                                                           addr_t         local_addr,
                                                           Genode::size_t size)
 {
-	/* special handling for context area */
+	/* special handling for stack area */
 	if (use_local_addr
-	 && local_addr == Native_config::context_area_virtual_base()
-	 && size       == Native_config::context_area_virtual_size()) {
+	 && local_addr == Native_config::stack_area_virtual_base()
+	 && size       == Native_config::stack_area_virtual_size()) {
 
 		/*
-		 * On the first request to reserve the context area, we flush the
+		 * On the first request to reserve the stack area, we flush the
 		 * initial mapping preserved in linker script and apply the actual
 		 * reservation. Subsequent requests are just ignored.
 		 */
@@ -73,8 +73,8 @@ addr_t Platform_env_base::Rm_session_mmap::_reserve_local(bool           use_loc
 		{
 			Context()
 			{
-				flush_context_area();
-				reserve_context_area();
+				flush_stack_area();
+				reserve_stack_area();
 			}
 		} inst;
 

repos/base-linux/src/base/thread/thread_linux.cc

@@ -19,6 +19,9 @@
 #include <base/sleep.h>
 #include <linux_cpu_session/linux_cpu_session.h>
 
+/* base-internal includes */
+#include <base/internal/stack.h>
+
 /* Linux syscall bindings */
 #include <linux_syscalls.h>
 
@@ -77,7 +80,7 @@ void Thread_base::_init_platform_thread(size_t weight, Type type)
 
 	/* for normal threads create an object at the CPU session */
 	if (type == NORMAL) {
-		_thread_cap = _cpu_session->create_thread(weight, _context->name);
+		_thread_cap = _cpu_session->create_thread(weight, _stack->name().string());
 		return;
 	}
 	/* adjust initial object state for main threads */

repos/base-linux/src/core/include/core_env.h

@@ -28,7 +28,6 @@
 /* base-internal includes */
 #include <base/internal/platform_env.h>
 
-
 namespace Genode {
 
 	/**

repos/base-linux/src/core/stack_area.cc

@@ -18,29 +18,29 @@
 #include <base/thread.h>
 
 /* base-internal includes */
-#include <base/internal/context_area.h>
+#include <base/internal/stack_area.h>
 
 
 /**
- * Region-manager session for allocating thread contexts
+ * Region-manager session for allocating stacks
  *
- * This class corresponds to the managed dataspace that is normally
- * used for organizing thread contexts with the thread context area.
- * It "emulates" the sub address space by adjusting the local address
- * argument to 'attach' with the offset of the thread context area.
+ * This class corresponds to the managed dataspace that is normally used for
+ * organizing stacks within the stack. It "emulates" the sub address space by
+ * adjusting the local address argument to 'attach' with the offset of the
+ * stack area.
  */
-class Context_area_rm_session : public Genode::Rm_session
+class Stack_area_rm_session : public Genode::Rm_session
 {
 	public:
 
-		Context_area_rm_session()
+		Stack_area_rm_session()
 		{
-			flush_context_area();
-			reserve_context_area();
+			flush_stack_area();
+			reserve_stack_area();
 		}
 
 		/**
-		 * Attach backing store to thread-context area
+		 * Attach backing store to stack area
 		 */
 		Local_addr attach(Genode::Dataspace_capability ds_cap,
 		                  Genode::size_t size, Genode::off_t offset,
@@ -49,9 +49,9 @@ class Context_area_rm_session : public Genode::Rm_session
 		{
 			using namespace Genode;
 
-			/* convert context-area-relative to absolute virtual address */
+			/* convert stack-area-relative to absolute virtual address */
 			addr_t addr = local_addr;
-			addr       += Native_config::context_area_virtual_base();
+			addr       += Native_config::stack_area_virtual_base();
 
 			/* use anonymous mmap for allocating stack backing store */
 			int   flags = MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE;
@@ -65,7 +65,7 @@ class Context_area_rm_session : public Genode::Rm_session
 		}
 
 		void detach(Local_addr local_addr) {
-			PWRN("context area detach from 0x%p - not implemented", (void *)local_addr); }
+			PWRN("stack area detach from 0x%p - not implemented", (void *)local_addr); }
 
 		Genode::Pager_capability add_client(Genode::Thread_capability) {
 			return Genode::Pager_capability(); }
@@ -81,7 +81,7 @@ class Context_area_rm_session : public Genode::Rm_session
 };
 
 
-class Context_area_ram_session : public Genode::Ram_session
+class Stack_area_ram_session : public Genode::Ram_session
 {
 	public:
 
@@ -102,19 +102,19 @@ class Context_area_ram_session : public Genode::Ram_session
 
 
 /**
- * Return single instance of the context-area RM and RAM session
+ * Return single instance of the stack-area RM and RAM session
  */
 namespace Genode {
 
-	Rm_session *env_context_area_rm_session()
+	Rm_session *env_stack_area_rm_session()
 	{
-		static Context_area_rm_session inst;
+		static Stack_area_rm_session inst;
 		return &inst;
 	}
 
-	Ram_session *env_context_area_ram_session()
+	Ram_session *env_stack_area_ram_session()
 	{
-		static Context_area_ram_session inst;
+		static Stack_area_ram_session inst;
 		return &inst;
 	}
 }

repos/base-linux/src/core/target.mk

@@ -24,7 +24,7 @@ SRC_CC        = main.cc \
                 signal_source_component.cc \
                 trace_session_component.cc \
                 thread_linux.cc \
-                context_area.cc \
+                stack_area.cc \
                 core_printf.cc \
                 thread.cc myself.cc
 

repos/base-linux/src/include/base/internal/platform_env.h

@@ -211,7 +211,7 @@ namespace Genode {
 					 * the common use case of managed dataspaces as mechanism
 					 * to reserve parts of the local address space from being
 					 * populated by the 'env()->rm_session()'. (i.e., for the
-					 * context area, or for the placement of consecutive
+					 * stack area, or for the placement of consecutive
 					 * shared-library segments)
 					 */
 					addr_t _base;

repos/base-linux/src/include/base/internal/stack_area.h

@@ -1,5 +1,5 @@
 /*
- * \brief  Linux-specific utilities for context area
+ * \brief  Linux-specific utilities for stack area
  * \author Christian Helmuth
  * \date   2013-09-26
  */
@@ -11,8 +11,8 @@
  * under the terms of the GNU General Public License version 2.
  */
 
-#ifndef _INCLUDE__BASE__INTERNAL__CONTEXT_AREA_H_
-#define _INCLUDE__BASE__INTERNAL__CONTEXT_AREA_H_
+#ifndef _INCLUDE__BASE__INTERNAL__STACK_AREA_H_
+#define _INCLUDE__BASE__INTERNAL__STACK_AREA_H_
 
 /* Genode includes */
 #include <base/thread.h>
@@ -24,12 +24,12 @@
 #include <sys/mman.h>
 
 
-static inline void flush_context_area()
+static inline void flush_stack_area()
 {
 	using namespace Genode;
 
-	void * const base = (void *) Native_config::context_area_virtual_base();
-	size_t const size = Native_config::context_area_virtual_size();
+	void * const base = (void *) Native_config::stack_area_virtual_base();
+	size_t const size = Native_config::stack_area_virtual_size();
 
 	int ret;
 	if ((ret = lx_munmap(base, size)) < 0) {
@@ -39,14 +39,14 @@ static inline void flush_context_area()
 }
 
 
-static inline Genode::addr_t reserve_context_area()
+static inline Genode::addr_t reserve_stack_area()
 {
 	using namespace Genode;
 
 	int const flags       = MAP_ANONYMOUS | MAP_PRIVATE;
 	int const prot        = PROT_NONE;
-	size_t const size     = Native_config::context_area_virtual_size();
-	void * const addr_in  = (void *)Native_config::context_area_virtual_base();
+	size_t const size     = Native_config::stack_area_virtual_size();
+	void * const addr_in  = (void *)Native_config::stack_area_virtual_base();
 	void * const addr_out = lx_mmap(addr_in, size, prot, flags, -1, 0);
 
 	/* reserve at local address failed - unmap incorrect mapping */
@@ -61,4 +61,4 @@ static inline Genode::addr_t reserve_context_area()
 	return (addr_t) addr_out;
 }
 
-#endif /* _INCLUDE__BASE__INTERNAL__CONTEXT_AREA_H_ */
+#endif /* _INCLUDE__BASE__INTERNAL__STACK_AREA_H_ */

repos/base-linux/src/ld/stack_area.nostdlib.ld

@@ -13,16 +13,16 @@
 
 PHDRS
 {
-	context_area PT_LOAD FLAGS(0);
+	stack_area PT_LOAD FLAGS(0);
 }
 
 SECTIONS
 {
 	. = 0x40000000;
-	_context_area_start = .;
+	_stack_area_start = .;
 	/*
-	 * Since Linux loads ldso page aligned, we align the context area after
+	 * Since Linux loads ldso page aligned, we align the stack area after
 	 * loading to a 1 MiB boundary, therefore we reserve one MiB more here.
 	 */
-	.context_area : { . += 0x10100000; } : context_area
+	.stack_area : { . += 0x10100000; } : stack_area
 }

repos/base-linux/src/ld/stack_area.stdlib.ld

@@ -14,6 +14,6 @@
 SECTIONS
 {
 	. = 0x40000000;
-	_context_area_start = .;
-	.context_area : { . += 0x10000000; }
+	_stack_area_start = .;
+	.stack_area : { . += 0x10000000; }
 }

repos/base-linux/src/lib/lx_hybrid/lx_hybrid.cc

@@ -20,9 +20,9 @@
 extern "C" int raw_write_str(const char *str);
 
 /**
- * Define context area
+ * Define stack area
  */
-Genode::addr_t _context_area_start;
+Genode::addr_t _stack_area_start;
 
 
 enum { verbose_atexit = false };
@@ -137,7 +137,7 @@ namespace Genode {
 	struct Thread_meta_data
 	{
 		/**
-		 * Filled out by 'thread_start' function in the context of the new
+		 * Filled out by 'thread_start' function in the stack of the new
 		 * thread
 		 */
 		Thread_base * const thread_base;
@@ -419,7 +419,7 @@ Thread_base::Thread_base(size_t weight, const char *name, size_t stack_size,
 		PERR("pthread_create failed (returned %d, errno=%d)",
 		     ret, errno);
 		destroy(env()->heap(), _tid.meta_data);
-		throw Context_alloc_failed();
+		throw Out_of_stack_space();
 	}
 
 	_tid.meta_data->wait_for_construction();