The frame-pointer-based backtrace does not work without enabling
-fno-omit-frame-pointer explicitly and in most cases leads to page
faults because non-pointer stack values are dereferenced during the
walk. The best we can do is to limit the backtrace walk to the stack of
the current thread to prevent page faults unrelated to the system state
without the use of the backtrace utility.
This commit introduces a printable Backtrace class usable in
Genode::log(), Genode::trace(), etc. The class is based on the new
function for_each_return_address(auto const &fn) that walks the stack in
its limits and calls fn() for each discovered return address on the
stack in the new os/include/os/backtrace.h. Archtecture-specific
stack-pointer retrieval and walk loops are implemented in dedicated
os/include/spec/<arch>/os/for_each_return_address.h files. Also, the
well-known Genode::backtrace() function (which logs the return-address
values) is provided for backwards compatibility.
Fixes#5078
Since the timer and timeout handling is part of the base library (the
dynamic linker), it belongs to the base repository.
Besides moving the timer and its related infrastructure (alarm, timeout
libs, tests) to the base repository, this patch also moves the timer
from the 'drivers' subdirectory directly to 'src' and disamibuates the
timer's build locations for the various kernels. Otherwise the different
timer implementations could interfere with each other when using one
build directory with multiple kernels.
Note that this patch changes the include paths for the former os/timer,
os/alarm.h, os/duration.h, and os/timed_semaphore.h to base/.
Issue #3101
Instead of holding SPEC-variable dependent files and directories inline
within the repository structure, move them into 'spec' subdirectories
at the corresponding levels, e.g.:
repos/base/include/spec
repos/base/mk/spec
repos/base/lib/mk/spec
repos/base/src/core/spec
...
Moreover, this commit removes the 'platform' directories. That term was
used in an overloaded sense. All SPEC-relative 'platform' directories are
now named 'spec'. Other files, like for instance those related to the
kernel/architecture specific startup library, where moved from 'platform'
directories to explicit, more meaningful places like e.g.: 'src/lib/startup'.
Fix#1673
