This patch replaces the former prominent use of pointers by references
wherever feasible. This has the following benefits:
* The contract between caller and callee becomes more obvious. When
passing a reference, the contract says that the argument cannot be
a null pointer. The caller is responsible to ensure that. Therefore,
the use of reference eliminates the need to add defensive null-pointer
checks at the callee site, which sometimes merely exist to be on the
safe side. The bottom line is that the code becomes easier to follow.
* Reference members must be initialized via an object initializer,
which promotes a programming style that avoids intermediate object-
construction states. Within core, there are still a few pointers
as member variables left though. E.g., caused by the late association
of 'Platform_thread' objects with their 'Platform_pd' objects.
* If no pointers are present as member variables, we don't need to
manually provide declarations of a private copy constructor and
an assignment operator to avoid -Weffc++ errors "class ... has
pointer data members [-Werror=effc++]".
This patch also changes a few system bindings on NOVA and Fiasco.OC,
e.g., the return value of the global 'cap_map' accessor has become a
reference. Hence, the patch touches a few places outside of core.
Fixes#3135
The patch adjust the code of the base, base-<kernel>, and os repository.
To adapt existing components to fix violations of the best practices
suggested by "Effective C++" as reported by the -Weffc++ compiler
argument. The changes follow the patterns outlined below:
* A class with virtual functions can no longer publicly inherit base
classed without a vtable. The inherited object may either be moved
to a member variable, or inherited privately. The latter would be
used for classes that inherit 'List::Element' or 'Avl_node'. In order
to enable the 'List' and 'Avl_tree' to access the meta data, the
'List' must become a friend.
* Instead of adding a virtual destructor to abstract base classes,
we inherit the new 'Interface' class, which contains a virtual
destructor. This way, single-line abstract base classes can stay
as compact as they are now. The 'Interface' utility resides in
base/include/util/interface.h.
* With the new warnings enabled, all member variables must be explicitly
initialized. Basic types may be initialized with '='. All other types
are initialized with braces '{ ... }' or as class initializers. If
basic types and non-basic types appear in a row, it is nice to only
use the brace syntax (also for basic types) and align the braces.
* If a class contains pointers as members, it must now also provide a
copy constructor and assignment operator. In the most cases, one
would make them private, effectively disallowing the objects to be
copied. Unfortunately, this warning cannot be fixed be inheriting
our existing 'Noncopyable' class (the compiler fails to detect that
the inheriting class cannot be copied and still gives the error).
For now, we have to manually add declarations for both the copy
constructor and assignment operator as private class members. Those
declarations should be prepended with a comment like this:
/*
* Noncopyable
*/
Thread(Thread const &);
Thread &operator = (Thread const &);
In the future, we should revisit these places and try to replace
the pointers with references. In the presence of at least one
reference member, the compiler would no longer implicitly generate
a copy constructor. So we could remove the manual declaration.
Issue #465
That seems nowadays the right place in order to tell the caller that the
thread couldn't be completely constructed. The return value false of
bind_thread causes in Cpu_thread_component the throwing of
Thread_creation_failed.
thread.run now passes
pthread.run now passes
Issue #2044
- adjust syscall bindings to support -fPIC
- read serial i/o ports from BIOS data area
- use autoconf.h provided by sel4
-- to avoid ambiguity between sel4 kernel and user libraries
-- remove manual set defines
- remove debug messages
- increase user virtual area to 3GB
Issue #1720
Issue #2044
This patch replaces the former 'Pd_session::bind_thread' function by a
PD-capability argument of the 'Cpu_session::create_thread' function, and
removes the ancient thread-start protocol via 'Rm_session::add_client' and
'Cpu_session::set_pager'. Threads are now bound to PDs at their creation
time and implicitly paged according to the address space of the PD.
Note the API change:
This patch changes the signature of the 'Child' and 'Process' constructors.
There is a new 'address_space' argument, which represents the region map
representing the child's address space. It is supplied separately to the
PD session capability (which principally can be invoked to obtain the
PD's address space) to allow the population of the address space
without relying on an 'Pd_session::address_space' RPC call.
Furthermore, a new (optional) env_pd argument allows the explicit
overriding of the PD capability handed out to the child as part of its
environment. It can be used to intercept the interaction of the child
with its PD session at core. This is used by Noux.
Issue #1938
The return code of assign_parent remained unused. So this patch
removes it.
The bind_thread function fails only due to platform-specific limitations
such as the exhaustion of ID name spaces, which cannot be sensibly
handled by the PD-session client. If occurred, such conditions used to
be reflected by integer return codes that were used for diagnostic
messages only. The patch removes the return codes and leaves the
diagnostic output to core.
Fixes#1842
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
This patch establishes a common organization of header files
internal to the base framework. The internal headers are located at
'<repository>/src/include/base/internal/'. This structure has been
choosen to make the nature of those headers immediately clear when
included:
#include <base/internal/lock_helper.h>
Issue #1832
This patch updates seL4 from the experimental branch of one year ago to
the master branch of version 2.1. The transition has the following
implications.
In contrast to the experimental branch, the master branch has no way to
manually define the allocation of kernel objects within untyped memory
ranges. Instead, the kernel maintains a built-in allocation policy. This
policy rules out the deallocation of once-used parts of untyped memory.
The only way to reuse memory is to revoke the entire untyped memory
range. Consequently, we cannot share a large untyped memory range for
kernel objects of different protection domains. In order to reuse memory
at a reasonably fine granularity, we need to split the initial untyped
memory ranges into small chunks that can be individually revoked. Those
chunks are called "untyped pages". An untyped page is a 4 KiB untyped
memory region.
The bootstrapping of core has to employ a two-stage allocation approach
now. For creating the initial kernel objects for core, which remain
static during the entire lifetime of the system, kernel objects are
created directly out of the initial untyped memory regions as reported
by the kernel. The so-called "initial untyped pool" keeps track of the
consumption of those untyped memory ranges by mimicking the kernel's
internal allocation policy. Kernel objects created this way can be of
any size. For example the phys CNode, which is used to store page-frame
capabilities is 16 MiB in size. Also, core's CSpace uses a relatively
large CNode.
After the initial setup phase, all remaining untyped memory is turned
into untyped pages. From this point on, new created kernel objects
cannot exceed 4 KiB in size because one kernel object cannot span
multiple untyped memory regions. The capability selectors for untyped
pages are organized similarly to those of page-frame capabilities. There
is a new 2nd-level CNode (UNTYPED_CORE_CNODE) that is dimensioned
according to the maximum amount of physical memory (1M entries, each
entry representing 4 KiB). The CNode is organized such that an index
into the CNode directly corresponds to the physical frame number of the
underlying memory. This way, we can easily determine a untyped page
selector for any physical addresses, i.e., for revoking the kernel
objects allocated at a specific physical page. The downside is the need
for another 16 MiB chunk of meta data. Also, we need to keep in mind
that this approach won't scale to 64-bit systems. We will eventually
need to replace the PHYS_CORE_CNODE and UNTYPED_CORE_CNODE by CNode
hierarchies to model a sparsely populated CNode.
The size constrain of kernel objects has the immediate implication that
the VM CSpaces of protection domains must be organized via several
levels of CNodes. I.e., as the top-level CNode of core has a size of
2^12, the remaining 20 PD-specific CSpace address bits are organized as
a 2nd-level 2^4 padding CNode, a 3rd-level 2^8 CNode, and several
4th-level 2^8 leaf CNodes. The latter contain the actual selectors for
the page tables and page-table entries of the respective PD.
As another slight difference from the experimental branch, the master
branch requires the explicit assignment of page directories to an ASID
pool.
Besides the adjustment to the new seL4 version, the patch introduces a
dedicated type for capability selectors. Previously, we just used to
represent them as unsigned integer values, which became increasingly
confusing. The new type 'Cap_sel' is a PD-local capability selector. The
type 'Cnode_index' is an index into a CNode (which is not generally not
the entire CSpace of the PD).
Fixes#1887
This commit eliminates the mutual interlaced taking of destruction lock,
list lock and weak pointer locks that could lead to a dead-lock situation
when a lock pointer was tried to construct while a weak object is in
destruction progress.
Now, all weak pointers are invalidated and dequeued at the very
beginning of the weak object's destruction. Moreover, before a weak pointer
gets invalidated during destruction of a weak object, it gets dequeued, and
the list lock is freed again to avoid the former dead-lock.
Fix#1607
This patch installs the parent endpoint selector and the PD's CNode into
a PD at its creation time. Furthermore, it initializes the IPC buffer
for the main thread of the new component.