Instead of changing the attributes (e.g., Xd bit) of the top-level page-tables,
set them to allow everything. Only leafs of the paging hierarchy are set
according to the paging attributes given by core. Otherwise, top-level page-
table attributes are changed during lifetime, which requires a TLB flush
operation (not intended in the semantic of the kernel/core).
This led to problems when using the non-executable features introduced by
issue #1723 in the recent past.
Recent work related to issue 1723 showed that there is potential
to get rid of code duplication in MMU fault handling especially
with regard to ARM cpus.
* Instead of always re-load page-tables when a thread context is switched
only do this when another user PD's thread is the next target,
core-threads are always executed within the last PD's page-table set
* remove the concept of the mode transition
* instead map the exception vector once in bootstrap code into kernel's
memory segment
* when a new page directory is constructed for a user PD, copy over the
top-level kernel segment entries on RISCV and X86, on ARM we use a designated
page directory register for the kernel segment
* transfer the current CPU id from bootstrap to core/kernel in a register
to ease first stack address calculation
* align cpu context member of threads and vms, because of x86 constraints
regarding the stack-pointer loading
* introduce Align_at template for members with alignment constraints
* let the x86 hardware do part of the context saving in ISS, by passing
the thread context into the TSS before leaving to user-land
* use one exception vector for all ARM platforms including Arm_v6
Fix#2091
* introduce new syscall (core-only) to create privileged threads
* take the privilege level of the thread into account
when doing a context switch
* map kernel segment as accessable for privileged code only
Ref #2091
Always switch to the "exception stack" instead of having a hardware initiated
stack switch during exceptions/interrupts when the privilege level changes only.
Moreover, this commit increases the exception stack slightly.
Ref #2091
* introduces central memory map for core/kernel
* on 32-bit platforms the kernel/core starts at 0x80000000
* on 64-bit platforms the kernel/core starts at 0xffffffc000000000
* mark kernel/core mappings as global ones (tagged TLB)
* move the exception vector to begin of core's binary,
thereby bootstrap knows from where to map it appropriately
* do not map boot modules into core anymore
* constrain core's virtual heap memory area
* differentiate in between user's and core's main thread's UTCB,
which now resides inside the kernel segment
Ref #2091
In the past, a signal context, that was chosen for handling by
'Signal_receiver::pending_signal and always triggered again before
the next call of 'pending_signal', caused all other contexts behind
in the list to starve. This was the case because 'pending_signal'
always took the first pending context in its context list.
We avoid this problem now by handling pending signals in a round-robin
fashion instead.
Ref #2532
Some x86 machines do have a LAPIC speed < 1000 ticks per millisecond
when configured to use the maximum divider (as it was always the case).
But we need microseconds precision for the timeout framework. Thus,
reduce the divider dynamically until the frequency fullfills our
requirements.
Ref #2400
There are hardware timers whose frequency can't be expressed as
ticks-per-microsecond integer-value because only a ticks-per-millisecond
integer-value is precise enough. We don't want to use expensive
floating-point values here but nonetheless want to translate from ticks
to time with microseconds precision. Thus, we split the input in two and
translate both parts separately. This way, we can raise precision by
shifting the values to their optimal bit position. Afterwards, the results
are shifted back and merged together again.
As this algorithm is not so trivial anymore and used by at least three
timer drivers (base-hw/x86_64, base-hw/cortex_a9, timer/pit), move it to a
generic header to avoid redundancy.
Ref #2400
Due to the simplicity of the algorithm that translated from timer ticks
to time, we lost microseconds precision although the timer allows for it.
Ref #2400
When running core as the kernel inside every component, a separate
stack area for core is needed that is different from the user-land
component's one.
Ref #2091
For most base platforms (except linux and sel4), the initialization of
boot modules is the same. Thus, merge this default implementation in the
new unit base/src/core/platform_rom_modules.cc.
Ref #2490
The kernel timer on RPI is able to measure time microseconds-precise.
Howeer, due to a bug, we dropped precision during the ticks-to-time
translation and return only milliseconds-precise time.
Ref #2400
rm_fault.run triggers write on read-only ROM provided by core, which
fails without this patch:
arm - "raised unhandled data abort"
x86 - (silent/invisible) busy loop because write fault gets never resolved
