This is a redesign of the root and parent interfaces to eliminate
blocking RPC calls.
- New session representation at the parent (base/session_state.h)
- base-internal root proxy mechanism as migration path
- Redesign of base/service.h
- Removes ancient 'Connection::KEEP_OPEN' feature
- Interface change of 'Child', 'Child_policy', 'Slave', 'Slave_policy'
- New 'Slave::Connection'
- Changed child-construction procedure to be compatible with the
non-blocking parent interface and to be easier to use
- The child's initial LOG session, its binary ROM session, and the
linker ROM session have become part of the child's envirenment.
- Session upgrading must now be performed via 'env.upgrade' instead
of performing a sole RPC call the parent. To make RAM upgrades
easier, the 'Connection' provides a new 'upgrade_ram' method.
Issue #2120
This patch fixes a race condition triggered by the thread test running
on Linux inside VirtualBox. The 'test_stack_alloc' sporadically produced
one of two errors: A segfault in the 'Thread::deinit_platform_thread' on
the attempt to access the 'native_thread' of the to-be-destructed thread
(this data structure is located on the thread's stack). Or, an error
message about a region conflict within the stack area.
The problem was that two instances of 'Region_map_mmap' issued a
sequence of munmap and mmap each. Even though each instance locked the
attach/detach operations, the lock was held per instance. In a situation
where two instances performed attach/detach operations in parallel, the
syscall sequences could interfere with each other.
In the test scenario, the two region-map instances are the test's
address space and the stack area. When creating a thread, the thread's
trace-control dataspace is attached at an arbitrary place (picked by
the Linux kernel) within the address space whereas the stack is attached
at the stack area. The problem is the following sequence:
Thread A wants to destruct a thread:
1. Remove stack from stack area
(issue unmap syscall)
2. Preserve virtual address range that was occupied from the stack
so that Linux won't use it
(issue mmap syscall)
Thread B wants to construct a thread:
1. Request trace-control dataspace from CPU session
2. Attach trace-control dataspace to address space at a location
picked by the Linux kernel
(issue mmap syscall)
The problem occurs when thread B's second step is executed in between
the steps 1 and 2 of thread A and the Linux kernel picks the
just-unmapped address as the location for the new trace-control mapping.
Now, the trace control dataspace is mapped at the virtual address that
was designated for the stack of the to-be-created thread, and the
attempt to map the real stack fails.
The patch fixes the problem by replacing the former region-map-local
locks by a component-global lock.
Furthermore, it cleans up core's implementation of the support function
for the region-map-mmap implementation, eliminating the temporary
unlocking of the region-map lock during RPC.
Besides adapting the components to the use of base/log.h, the patch
cleans up a few base headers, i.e., it removes unused includes from
root/component.h, specifically base/heap.h and
ram_session/ram_session.h. Hence, components that relied on the implicit
inclusion of those headers have to manually include those headers now.
While adjusting the log messages, I repeatedly stumbled over the problem
that printing char * arguments is ambiguous. It is unclear whether to
print the argument as pointer or null-terminated string. To overcome
this problem, the patch introduces a new type 'Cstring' that allows the
caller to express that the argument should be handled as null-terminated
string. As a nice side effect, with this type in place, the optional len
argument of the 'String' class could be removed. Instead of supplying a
pair of (char const *, size_t), the constructor accepts a 'Cstring'.
This, in turn, clears the way let the 'String' constructor use the new
output mechanism to assemble a string from multiple arguments (and
thereby getting rid of snprintf within Genode in the near future).
To enforce the explicit resolution of the char * ambiguity, the 'char *'
overload of the 'print' function is marked as deleted.
Issue #1987
Thread stacks with less than 4K usable space are insufficient for our
implementation of Linux exception signal handling. If such a unusually
small stack overflows the SIGSEGV handler will not be able to print the
diagnostic message leaving no hint of the cause of the stuck process.
This patch establishes the sole use of generic headers across all
kernels. The common 'native_capability.h' is based on the version of
base-sel4. All traditional L4 kernels and Linux use the same
implementation of the capability-lifetime management. On base-hw, NOVA,
Fiasco.OC, and seL4, custom implementations (based on their original
mechanisms) are used, with the potential to unify them further in the
future.
This change achieves binary compatibility of dynamically linked programs
across all kernels.
Furthermore, the patch introduces a Native_capability::print method,
which allows the easy output of the kernel-specific capability
representation using the base/log.h API.
Issue #1993
This patch alleviates the need for a Native_capability::Dst at the API
level. The former use case of this type as argument to
Deprecated_env::reinit uses the opaque Native_capability::Raw type
instead. The 'Raw' type contains the portion of the capability that is
transferred as-is when delegating the capability (i.e., when installing
the parent capability into a new component, or when installing a new
parent capability into a new forked Noux process). This information can
be retrieved via the new Native_capability::raw method.
Furthermore, this patch moves the functions for retriving the parent
capability to base/internal/parent_cap.h, which is meant to be
implemented in platform-specific ways. It replaces the former set of
startup/internal/_main_parent_cap.h headers.
Issue #1993
The alternate stack must use the stack area as, e.g., Thread::myself()
depends on this property. Hybrid components do not depend on this
property and, therefore, use a static stack buffer.
Fixes#1935
This patch introduces the Genode::raw function that prints output
directly via a low-level kernel mechanism, if available.
On base-linux, it replaces the former 'raw_write_str' function.
On base-hw, it replaces the former kernel/log.h interface.
Fixes#2012
This patch moves the thread operations from the 'Cpu_session'
to the 'Cpu_thread' interface.
A noteworthy semantic change is the meaning of the former
'exception_handler' function, which used to define both, the default
exception handler or a thread-specific signal handler. Now, the
'Cpu_session::exception_sigh' function defines the CPU-session-wide
default handler whereas the 'Cpu_thread::exception_sigh' function
defines the thread-specific one.
To retain the ability to create 'Child' objects without invoking a
capability, the child's initial thread must be created outside the
'Child::Process'. It is now represented by the 'Child::Initial_thread',
which is passed as argument to the 'Child' constructor.
Fixes#1939
The recent move of the initial three region maps into the PD session
breaks the noux.run test on Linux because the address spaces are locally
managed on this platform but the generic code of Noux still tries to
execute the regular procedure of creating the virtualized PD session for
a new Noux process. This patch handles a corner case that occurs on
Linux but no other platform. It enables the successful creation of the
virtualized PD session so that the test runs to completion. Still noux
on Linux remains to be limited to non-forking programs.
Issue #1938
This patch cleans up the thread API and comes with the following
noteworthy changes:
- Introduced Cpu_session::Weight type that replaces a formerly used
plain integer value to prevent the accidental mix-up of
arguments.
- The enum definition of Cpu_session::DEFAULT_WEIGHT moved to
Cpu_session::Weight::DEFAULT_WEIGHT
- New Thread constructor that takes a 'Env &' as first argument.
The original constructors are now marked as deprecated. For the
common use case where the default 'Weight' and 'Affinity' are
used, a shortcut is provided. In the long term, those two
constructors should be the only ones to remain.
- The former 'Thread<>' class template has been renamed to
'Thread_deprecated'.
- The former 'Thread_base' class is now called 'Thread'.
- The new 'name()' accessor returns the thread's name as 'Name'
object as centrally defined via 'Cpu_session::Name'. It is meant to
replace the old-fashioned 'name' method that takes a buffer and size
as arguments.
- Adaptation of the thread test to the new API
Issue #1954
This patch moves the base library from src/base to src/lib/base,
flattens the library-internal directory structure, and moves the common
parts of the library-description files to base/lib/mk/base.inc and
base/lib/mk/base-common.inc.
Furthermore, the patch fixes a few cosmetic issues (whitespace and
comments only) that I encountered while browsing the result.
Fixes#1952
