/*
 * \brief  Support code for the thread API
 * \author Norman Feske
 * \author Stefan Kalkowski
 * \date   2010-01-13
 */

/*
 * Copyright (C) 2010-2015 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU General Public License version 2.
 */

/* Genode includes */
#include <rm_session/rm_session.h>
#include <ram_session/ram_session.h>
#include <base/printf.h>
#include <base/synced_allocator.h>
#include <base/thread.h>

/* base-internal includes */
#include <base/internal/stack_area.h>

/* local includes */
#include <platform.h>
#include <map_local.h>
#include <dataspace_component.h>

using namespace Genode;


/**
 * Region-manager session for allocating stacks
 *
 * This class corresponds to the managed dataspace that is normally
 * used for organizing stacks within the stack area.
 * In contrast to the ordinary implementation, core's version does
 * not split between allocation of memory and virtual memory management.
 * Due to the missing availability of "real" dataspaces and capabilities
 * referring to it without having an entrypoint in place, the allocation
 * of a dataspace has no effect, but the attachment of the thereby "empty"
 * dataspace is doing both: allocation and attachment.
 */
class Stack_area_rm_session : public Rm_session
{
	private:

		using Ds_slab = Synced_allocator<Tslab<Dataspace_component,
		                                       get_page_size()> >;

		Ds_slab _ds_slab { platform()->core_mem_alloc() };

		enum { verbose = false };

	public:

		/**
		 * Allocate and attach on-the-fly backing store to stack area
		 */
		Local_addr attach(Dataspace_capability ds_cap, /* ignored capability */
		                  size_t size, off_t offset,
		                  bool use_local_addr, Local_addr local_addr,
		                  bool executable)
		{
			/* allocate physical memory */
			size = round_page(size);
			void *phys_base;
			Range_allocator *ra = platform_specific()->ram_alloc();
			if (ra->alloc_aligned(size, &phys_base,
				                  get_page_size_log2()).is_error()) {
				PERR("could not allocate backing store for new stack");
				return (addr_t)0;
			}

			if (verbose)
				PDBG("phys_base = %p, size = 0x%zx", phys_base, size);

			Dataspace_component *ds = new (&_ds_slab)
				Dataspace_component(size, 0, (addr_t)phys_base, CACHED, true, 0);
			if (!ds) {
				PERR("dataspace for core stack does not exist");
				return (addr_t)0;
			}

			addr_t core_local_addr = stack_area_virtual_base() + (addr_t)local_addr;

			if (verbose)
				PDBG("core_local_addr = %lx, phys_addr = %lx, size = 0x%zx",
				     core_local_addr, ds->phys_addr(), ds->size());

			if (!map_local(ds->phys_addr(), core_local_addr,
			               ds->size() >> get_page_size_log2())) {
				PERR("could not map phys %lx at local %lx",
				     ds->phys_addr(), core_local_addr);
				return (addr_t)0;
			}

			ds->assign_core_local_addr((void*)core_local_addr);

			return local_addr;
		}

		void detach(Local_addr local_addr)
		{
			using Genode::addr_t;

			if ((addr_t)local_addr >= stack_area_virtual_size())
				return;

			addr_t const detach = stack_area_virtual_base() + (addr_t)local_addr;
			addr_t const stack  = stack_virtual_size();
			addr_t const pages  = ((detach & ~(stack - 1)) + stack - detach)
			                      >> get_page_size_log2();

			unmap_local(detach, pages);
		}

		Pager_capability add_client(Thread_capability) {
			return Pager_capability(); }

		void remove_client(Pager_capability) { }

		void fault_handler(Signal_context_capability) { }

		State state() { return State(); }

		Dataspace_capability dataspace() { return Dataspace_capability(); }
};


class Stack_area_ram_session : public Ram_session
{
	public:

		Ram_dataspace_capability alloc(size_t size, Cache_attribute cached) {
			return reinterpret_cap_cast<Ram_dataspace>(Native_capability()); }

		void free(Ram_dataspace_capability ds) { }

		int ref_account(Ram_session_capability ram_session) { return 0; }

		int transfer_quota(Ram_session_capability ram_session, size_t amount) {
			return 0; }

		size_t quota() { return 0; }

		size_t used() { return 0; }
};


/**
 * Return single instance of the context-area RM and RAM session
 */
namespace Genode {

	Rm_session *env_stack_area_rm_session()
	{
		static Stack_area_rm_session inst;
		return &inst;
	}

	Ram_session *env_stack_area_ram_session()
	{
		static Stack_area_ram_session inst;
		return &inst;
	}
}