core: add Platform::max_caps()

This method returns the kernel-specific system-global limit of the total
number of capabilities.

Issue #2398

repos/base-fiasco/src/core/include/platform.h

@@ -16,6 +16,7 @@
 #define _CORE__INCLUDE__PLATFORM_H_
 
 #include <base/allocator_avl.h>
+#include <base/internal/capability_space.h>
 
 #include "synced_range_allocator.h"
 #include "platform_generic.h"
@@ -139,15 +140,17 @@ namespace Genode {
 			 ** Generic platform interface **
 			 ********************************/
 
-			Range_allocator *core_mem_alloc() { return &_ram_alloc; }
+			Range_allocator *core_mem_alloc() override { return &_ram_alloc; }
-			Range_allocator *ram_alloc()      { return &_ram_alloc; }
+			Range_allocator *ram_alloc()      override { return &_ram_alloc; }
-			Range_allocator *io_mem_alloc()   { return &_io_mem_alloc; }
+			Range_allocator *io_mem_alloc()   override { return &_io_mem_alloc; }
-			Range_allocator *io_port_alloc()  { return &_io_port_alloc; }
+			Range_allocator *io_port_alloc()  override { return &_io_port_alloc; }
-			Range_allocator *irq_alloc()      { return &_irq_alloc; }
+			Range_allocator *irq_alloc()      override { return &_irq_alloc; }
-			Range_allocator *region_alloc()   { return &_region_alloc; }
+			Range_allocator *region_alloc()   override { return &_region_alloc; }
-			addr_t           vm_start() const { return _vm_start; }
+			addr_t           vm_start() const override { return _vm_start; }
-			size_t           vm_size()  const { return _vm_size; }
+			size_t           vm_size()  const override { return _vm_size; }
-			Rom_fs          *rom_fs()         { return &_rom_fs; }
+			Rom_fs          *rom_fs()         override { return &_rom_fs; }
+
+			size_t max_caps() const { return Capability_space::max_caps(); }
 
 			void wait_for_exit();
 	};

repos/base-foc/src/core/include/platform.h

@@ -158,6 +158,8 @@ namespace Genode {
 			Rom_fs           *rom_fs()         { return &_rom_fs;        }
 			Affinity::Space   affinity_space() const;
 
+			size_t max_caps() const override { return cap_idx_alloc()->max_caps(); }
+
 			void wait_for_exit();
 	};
 }

repos/base-foc/src/include/base/internal/cap_alloc.h

@@ -134,6 +134,8 @@ namespace Genode {
 			{
 				construct_at<Cap_index_allocator_tpl<T, SZ> >(this);
 			}
+
+			size_t max_caps() const override { return SZ; }
 	};
 }
 

repos/base-foc/src/include/base/internal/cap_map.h

@@ -113,6 +113,11 @@ namespace Genode {
 			 * Redo construction of the object
 			 */
 			virtual void reinit() = 0;
+
+			/**
+			 * Return capacity of allocator
+			 */
+			virtual size_t max_caps() const = 0;
 	};
 
 

repos/base-hw/src/core/platform.h

@@ -25,6 +25,7 @@
 #include <hw/memory_region.h>
 #include <kernel/configuration.h>
 #include <kernel/core_interface.h>
+#include <kernel/pd.h>
 
 /* core includes */
 #include <platform_generic.h>
@@ -140,6 +141,12 @@ class Genode::Platform : public Genode::Platform_generic
 
 		Affinity::Space affinity_space() const {
 			return Affinity::Space(NR_OF_CPUS); }
+
+		/*
+		 * The system-wide maximum number of capabilities is constrained
+		 * by core's local capability space.
+		 */
+		size_t max_caps() const override { return Kernel::Pd::max_cap_ids; }
 };
 
 #endif /* _CORE__PLATFORM_H_ */

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

@@ -83,15 +83,28 @@ namespace Genode {
 			 ** Generic platform interface **
 			 ********************************/
 
-			Range_allocator *core_mem_alloc() { return &_core_mem_alloc; }
+			Range_allocator *core_mem_alloc() override { return &_core_mem_alloc; }
-			Range_allocator *ram_alloc()      { return &_ram_alloc; }
+			Range_allocator *ram_alloc()      override { return &_ram_alloc; }
-			Range_allocator *io_mem_alloc()   { return 0; }
+			Range_allocator *io_mem_alloc()   override { return 0; }
-			Range_allocator *io_port_alloc()  { return 0; }
+			Range_allocator *io_port_alloc()  override { return 0; }
-			Range_allocator *irq_alloc()      { return 0; }
+			Range_allocator *irq_alloc()      override { return 0; }
-			Range_allocator *region_alloc()   { return 0; }
+			Range_allocator *region_alloc()   override { return 0; }
-			addr_t           vm_start() const { return 0; }
+			addr_t           vm_start() const override { return 0; }
-			size_t           vm_size()  const { return 0; }
+			size_t           vm_size()  const override { return 0; }
-			Rom_fs          *rom_fs()         { return 0; }
+			Rom_fs          *rom_fs()         override { return 0; }
+
+			/*
+			 * On Linux, the maximum number of capabilities is primarily
+			 * constrained by the limited number of file descriptors within
+			 * core. Each dataspace and and each thread consumes one
+			 * descriptor. However, all capabilies managed by the same
+			 * entrypoint share the same file descriptor such that the fd
+			 * limit would be an overly pessimistic upper bound.
+			 *
+			 * Hence, we define the limit somewhat arbitrary on Linux and
+			 * accept that scenarios may break when reaching core's fd limit.
+			 */
+			size_t max_caps() const override { return 10000; }
 
 			void wait_for_exit();
 	};

repos/base-nova/src/core/include/platform.h

@@ -51,6 +51,8 @@ namespace Genode {
 
 			addr_t _map_pages(addr_t phys_page, addr_t pages);
 
+			size_t _max_caps = 0;
+
 		public:
 
 			/**
@@ -72,6 +74,7 @@ namespace Genode {
 			addr_t           vm_start() const override { return _vm_base; }
 			size_t           vm_size()  const override { return _vm_size;  }
 			Rom_fs          *rom_fs()         override { return &_rom_fs; }
+			size_t           max_caps() const override { return _max_caps; }
 
 			void wait_for_exit() override;
 			bool supports_unmap() override { return true; }

repos/base-nova/src/core/platform.cc

@@ -642,7 +642,8 @@ Platform::Platform() :
 	}
 
 	/* add capability selector ranges to map */
-	unsigned index = 0x2000;
+	unsigned const first_index = 0x2000;
+	unsigned index = first_index;
 	for (unsigned i = 0; i < 32; i++)
 	{
 		void * phys_ptr = 0;
@@ -658,6 +659,7 @@ Platform::Platform() :
 
 		index = range->base() + range->elements();
 	}
+	_max_caps = index - first_index;
 
 	/* add idle ECs to trace sources */
 	for (unsigned genode_cpu_id = 0; genode_cpu_id < _cpus.width(); genode_cpu_id++) {

repos/base-okl4/src/core/include/platform.h

@@ -24,6 +24,9 @@
 #include <core_region_map.h>
 #include <core_mem_alloc.h>
 
+/* base-internal includes */
+#include <base/internal/capability_space.h>
+
 /* OKL4 includes */
 namespace Okl4 { extern "C" {
 #include <bootinfo/bootinfo.h>
@@ -105,15 +108,16 @@ namespace Genode {
 			 ** Generic platform interface **
 			 ********************************/
 
-			Range_allocator *ram_alloc()      { return  _core_mem_alloc.phys_alloc(); }
+			Range_allocator *ram_alloc()      override { return  _core_mem_alloc.phys_alloc(); }
-			Range_allocator *io_mem_alloc()   { return &_io_mem_alloc; }
+			Range_allocator *io_mem_alloc()   override { return &_io_mem_alloc; }
-			Range_allocator *io_port_alloc()  { return &_io_port_alloc; }
+			Range_allocator *io_port_alloc()  override { return &_io_port_alloc; }
-			Range_allocator *irq_alloc()      { return &_irq_alloc; }
+			Range_allocator *irq_alloc()      override { return &_irq_alloc; }
-			Range_allocator *region_alloc()   { return  _core_mem_alloc.virt_alloc(); }
+			Range_allocator *region_alloc()   override { return  _core_mem_alloc.virt_alloc(); }
-			Range_allocator *core_mem_alloc() { return &_core_mem_alloc; }
+			Range_allocator *core_mem_alloc() override { return &_core_mem_alloc; }
-			addr_t           vm_start() const { return _vm_start; }
+			addr_t           vm_start() const override { return _vm_start; }
-			size_t           vm_size()  const { return _vm_size; }
+			size_t           vm_size()  const override { return _vm_size; }
-			Rom_fs          *rom_fs()         { return &_rom_fs; }
+			Rom_fs          *rom_fs()         override { return &_rom_fs; }
+			size_t           max_caps() const override { return Capability_space::max_caps(); }
 
 			void wait_for_exit();
 
@@ -124,7 +128,7 @@ namespace Genode {
 			 ** OKL4-specific platform interface **
 			 **************************************/
 
-			addr_t           utcb_base() { return _utcb_base; }
+			addr_t utcb_base() { return _utcb_base; }
 	};
 }
 

repos/base-pistachio/src/core/include/platform.h

@@ -15,8 +15,13 @@
 #ifndef _CORE__INCLUDE__PLATFORM_H_
 #define _CORE__INCLUDE__PLATFORM_H_
 
+/* Genode includes */
 #include <base/allocator_avl.h>
 
+/* base-internal includes */
+#include <base/internal/capability_space.h>
+
+/* core-local includes */
 #include "synced_range_allocator.h"
 #include "platform_generic.h"
 #include "platform_thread.h"
@@ -136,15 +141,16 @@ namespace Genode {
 			 ** Generic platform interface **
 			 ********************************/
 
-			Range_allocator *core_mem_alloc() { return &_ram_alloc; }
+			Range_allocator *core_mem_alloc() override { return &_ram_alloc; }
-			Range_allocator *ram_alloc()      { return &_ram_alloc; }
+			Range_allocator *ram_alloc()      override { return &_ram_alloc; }
-			Range_allocator *io_mem_alloc()   { return &_io_mem_alloc; }
+			Range_allocator *io_mem_alloc()   override { return &_io_mem_alloc; }
-			Range_allocator *io_port_alloc()  { return &_io_port_alloc; }
+			Range_allocator *io_port_alloc()  override { return &_io_port_alloc; }
-			Range_allocator *irq_alloc()      { return &_irq_alloc; }
+			Range_allocator *irq_alloc()      override { return &_irq_alloc; }
-			Range_allocator *region_alloc()   { return &_region_alloc; }
+			Range_allocator *region_alloc()   override { return &_region_alloc; }
-			addr_t           vm_start() const { return _vm_start; }
+			addr_t           vm_start() const override { return _vm_start; }
-			size_t           vm_size()  const { return _vm_size; }
+			size_t           vm_size()  const override { return _vm_size; }
-			Rom_fs          *rom_fs()         { return &_rom_fs; }
+			Rom_fs          *rom_fs()         override { return &_rom_fs; }
+			size_t           max_caps() const override { return Capability_space::max_caps(); }
 
 			void wait_for_exit();
 

repos/base-sel4/src/core/include/platform.h

@@ -198,6 +198,10 @@ class Genode::Platform : public Platform_generic
 		size_t region_alloc_size_at(void * addr) {
 			return (*_core_mem_alloc.virt_alloc())()->size_at(addr); }
 
+		size_t max_caps() const override
+		{
+			return 1UL << Core_cspace::NUM_CORE_SEL_LOG2;
+		}
 };
 
 #endif /* _CORE__INCLUDE__PLATFORM_H_ */

repos/base/src/core/capability_space.cc

@@ -41,9 +41,11 @@ using namespace Genode;
  */
 namespace {
 
+	enum { NUM_LOCAL_CAPS = 64*1024 };
+
 	struct Local_capability_space
 	:
-		Capability_space_tpl<64*1024, Native_capability::Data>
+		Capability_space_tpl<NUM_LOCAL_CAPS, Native_capability::Data>
 	{ };
 
 	static Local_capability_space &local_capability_space()
@@ -94,6 +96,9 @@ Native_capability Capability_space::import(Rpc_destination dst, Rpc_obj_key key)
 }
 
 
+size_t Capability_space::max_caps() { return NUM_LOCAL_CAPS; }
+
+
 void Capability_space::print(Output &out, Native_capability::Data const &data)
 {
 	local_capability_space().print(out, data);

repos/base/src/core/include/platform_generic.h

@@ -99,6 +99,11 @@ namespace Genode {
 			{
 				return Affinity::Space(1);
 			}
+
+			/**
+			 * Return system-wide maximum number of capabilities
+			 */
+			virtual size_t max_caps() const = 0;
 	};
 
 

repos/base/src/include/base/internal/capability_space.h

@@ -47,6 +47,11 @@ namespace Genode { namespace Capability_space {
 	 */
 	Rpc_obj_key rpc_obj_key(Native_capability::Data const &);
 
+	/**
+	 * Return capacity of the capability space
+	 */
+	size_t max_caps();
+
 	/**
 	 * Print internal capability representation
 	 */