Inside the code of cloneFunc(…) //syscall_emul.hh
cp->initState(); //line 1483
p->clone(tc, ctc, cp, flags); //line 1484
…
ctc->clearArchRegs(); //line 1503
OS::archClone(flags, p, cp, tc, ctc, newStack, tlsPtr); //line 1505
…
At line 1483, initState() is called and the activateContext() of the
corresponding MinorCPU is eventually called. The actual architecture
clone happens at line 1505 where PC of the new thread could have a
correct value.
In the existing implementation of MinorCPU::activateContext(ThreadID
thread_id), the below line 275 is called
pipeline->wakeupFetch(thread_id);
to start fetching instruction with current value of PC, which is 0x0,
leading to panic “Page table fault when accessing virtual address 0”.
This is because the OS::archClone() is not yet called. So, the below bug
fix handles the wakeup fetch for a thread for two scenarios:
...
if (!threads[thread_id]->getUseForClone())
{ //the thread is not cloned
pipeline->wakeupFetch(thread_id);
} else {//the thread from clone
if (fetchEventWrapper != NULL)
delete fetchEventWrapper;
fetchEventWrapper = new EventFunctionWrapper([this, thread_id]
{pipeline->wakeupFetch(thread_id);}, "wakeupFetch");
schedule(*fetchEventWrapper, clockEdge(Cycles(0)));
}
...
If a thread is not cloned, pipeline->wakeupFetch() is called
immediately.
For the cloned thread, the above bug fix delays the execution of
pipeline->wakeupFetch()
after the OS::archClone is done. ThreadContext::getUseForClone() return
true if a thread is cloned.
A member variable fetchEventWrapper is added to MinorCPU class for
delayed fetch event.
A member variable useForClone and its corresponding get/set methods are
added to ThreadContext class. This approach allows future reuse of this
useForClone variable by other CPU models if needed and also avoid lots
of changes resulted by modifying parameters of activateContext () and
activate() which are defined as override.
Inside the syscall cloneFunc, the useForClone member of a ThreadContext
object is set via its set method right before Process's initState() is
called, shown as below.
ctc->setUseForClone(true);
cp->initState();
p->clone(tc, ctc, cp, flags);
A few previously failed RISC-V ASM tests have been open in tests.py file
after the bug fix works.
JIRA issue: https://gem5.atlassian.net/browse/GEM5-374
Change-Id: Ibffe46522e2617443d29f49df180692c54830f14
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/37315
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
The event in KVM x86 SE mode plays double duty, triggering a system call
or a page fault depending on where it's called from (the system call
handler vs page fault handler).
This means we can eliminate the page fault gem5 op and the
pseudo_inst.hh switching header file.
This change touches a lot of things, but there wasn't really a good
place to split it up which still made sense and was consistent and
functional.
Change-Id: Ic414829917bcbd421893aa6c89d78273e4926b78
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34165
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The *vast* majority of SimObjects use the standard boilerplate version
of their Params::create() method which just returns new
ClassName(*this); Rather than force every class to define this method,
or annoy and frustrate users who forget and then get linker errors, this
change automates the default while leaving the possibility of defining a
custom create() method for non-default cases.
The situations this mechanism handles can be first broken down by
whether the SimObject class has a constructor of the normal form, ie one
that takes a const Params reference as its only parameter.
If no, then no default create() implementation is defined, and one
*must* be defined by the user.
If yes, then a default create() implementation is defined as a weak
symbol. If the user still wants to define their own create method for
some reason, perhaps to add debugging info, to keep track of instances
in c++, etc., then they can and it will override the weak symbol and
take precedence.
The way this is implemented is not straightforward. A set of classes are
defined which use SFINAE which either map in the real Params type or a
dummy based on whether the normal constructor exists in the SimObject
class. Then those classes are used to define *a* create method.
Depending on how the SFINAE works out, that will either be *the* create
method on the real Params struct, or a create method on a dummy class
set up to just absorb the definition and then go away. In either case the
create() method is a weak symbol, but in the dummy case it
doesn't/shouldn't matter.
Annoyingly the compiler insists that the weak symbol be visible. While
that makes total sense normally, we don't actually care what happens to
the weak symbol if it's attached to the dummy class. Unfortunately that
means we need to make the dummy class globally visible, although we put
it in a namespace to keep it from colliding with anything useful.
Change-Id: I3767a8dc8dc03665a72d5e8c294550d96466f741
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35942
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This is a way to send a very generic poke to the workload so it can do
something. It's up to the workload to know what information to look for
to interpret an event, such as what PC it came from, what register
values are, or the context of the workload itself (is this SE mode? which
OS is running?).
Change-Id: Ifa4bdf3b5c5a934338c50600747d0b65f4b5eb2b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34162
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The parseParam and showParam functions partially worked using template
specialization, and partially worked using function overloading. The
template specialization could be resolved later once other functions
were added, but the regular function overloads could not. That meant
that it was practically impossible to add new definitions of those two
functions local to the types they worked with.
Also, because C++ does not allow partial specialization of template
functions, it would not be possible to truly use specialization to wire
in BitUnion types.
To fix these problems, these functions have been turned into structs
which wrap static functions. These can be partially specialized as
desired, making them compatible with BitUnions. Also, it's not possible
to overload structures like it is with functions, so only specialization
is considered, not overloading.
While making these changes, these functions (now structs) were also
reworked so that they share implementation more, and are generally
more streamlined.
Given the fact that the previous parseParam and showParam functions
could not actually be expanded beyond serialize.hh, and were not
actually called directly by any code outside of that file, they should
have never been considered part of the API.
Now that these structs actually *can* be specialized outside of this
file, they should be considered part of the interface.
Change-Id: Ic8e677b97fda8378ee1da1f3cf6001e02783fde3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36280
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
These had been written specifically for the vector, list, set, and C
style array types. This change reworks them to share an implementation,
and to work with more general types. The arrayParamOut method requires
std::begin() and std::end() to accept that type, and the arrayParamIn
method requires either insert or push_back, or the type to be an array.
Also fix up a couple of files which accidentally depended on includes in
the serialize headers which are no longer necessary.
Change-Id: I6ec4fe3bb900603bbb4e35c4efa620c249942452
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36277
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The create() method on Params structs usually instantiate SimObjects
using a constructor which takes the Params struct as a parameter
somehow. There has been a lot of needless variation in how that was
done, making it annoying to pass Params down to base classes. Some of
the different forms were:
const Params &
Params &
Params *
const Params *
Params const*
This change goes through and fixes up every constructor and every
create() method to use the const Params & form. We use a reference
because the Params struct should never be null. We use const because
neither the create method nor the consuming object should modify the
record of the parameters as they came in from the config. That would
make consuming them not idempotent, and make it impossible to tell what
the actual simulation configuration was since it would change from any
user visible form (config script, config.ini, dot pdf output).
Change-Id: I77453cba52fdcfd5f4eec92dfb0bddb5a9945f31
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35938
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Global stats are currently exposed using the legacy stat system (i.e.,
without a parent group). This change moves global stats from
stat_control.cc to a group that gets exported from the Root object.
The implementation adds the Root::Stats class which has a single
global instance. This instance is exposed to the rest of the simulator
using the global rootStats symbol. The intention is that objects that
need global statistics in formulas access them through the rootStats
object.
The global names simSeconds, simTicks, simFreq, and hostSeconds are
now references to their respective members in the rootStats object.
Change-Id: I267b5244a0bcca93dd2dcf03388e7085bdd79c9e
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35616
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This change replaces the __attribute__ syntax with the now standard [[]]
syntax. It also reorganizes compiler.hh so that all special macros have
some explanatory text saying what they do, and each attribute which has a
standard version can use that if available and what version of c++ it's
standard in is put in a comment.
Also, the requirements as far as where you put [[]] style attributes are
a little more strict than the old school __attribute__ style. The use of
the attribute macros was updated to fit these new, more strict
requirements.
Change-Id: Iace44306a534111f1c38b9856dc9e88cd9b49d2a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35219
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
System calls should now be requested from the workload directly and not
routed through ExecContext or ThreadContext interfaces. That removes a
major special case for SE mode from those interfaces.
For now, when the SE workload gets a request for a system call, it
dispatches it to the appropriate Process object. In the future, the
ISA specific Workload subclasses will be responsible for handling system
calls and not the Process classes.
For simplicity, the Workload syscall() method is defined in the base
class but will panic everywhere except when SEWorkload overrides it. In
the future, this mechanism will turn into a way to request generic
services from the workload which are not necessarily system calls. For
instance, it could be a way to request handling of a page fault without
having to have another PseudoInst just for that purpose.
Change-Id: I18d36d64c54adf4f4f17a62e7e006ff2fc0b22f1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33282
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The workload object is still optional for the sake of compatibility,
even though it probably shouldn't be in the long term. If a simulation
is just a collection of components with nothing in particular running on
it, for instance driven by a traffic generator, should it even have a
System object in the first place?
Change-Id: I8bcda72bdfa3730248226fb62f0bba9a83243d95
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33278
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
We currently register global CPU statistics such as sim_insts and
sim_ops from stat_control.cc. This adds an undesriable dependency on
BaseCPU from stats_contro.cc. Move the CPU-specific stats to a global
stat group in BaseCPU. This group is merged with the Root object's
stats which means that they appear as global stats in a typical stat
dump.
Care has been taken to keep the old stat names. However, the order of
the stats.txt will be slightly different due to the way legacy stats
and new-style stats are serialised.
Change-Id: I5410bc432f1a8cf3de58b08ca54a1aa2711d9c76
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34395
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
There are cases where a system's byte order isn't well-defined from an
ISA. For example, Arm implementations can be either big or little
endian, sometimes depending on a boot parameter. Decouple the CPU byte
order from the System's default byte order by exposing the System's
byte order as a parameter that defaults to big endian for SPARC and
POWER and little endian for everything else.
Change-Id: I24f87ea3a61b05042ede20dea6bb056af071d2c0
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33175
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabeblack@google.com>
When the system call happens during the execution of the system call
instruction, it can be ambiguous what state takes precedence, the state
update from the instruction or the system call. These may be tracked
differently and found in an unpredictable order in, for example, the O3
CPU. An instruction can avoid updating any state explicitly, but
implicitly updated state (specifically the PC) will always update,
whether the instruction wants it to or not.
If the system call can be deferred by using a Fault object, then it's no
longer ambiguous. The PC update will be discarded, and the system call
can set the PC however it likes. Because there is no implicit PC update,
the PC needs to be walked forward, either to what it would have been
anyway, or to what the system call set in NPC.
In addition, because of the existing semantics around handling Faults,
the instruction no longer needs to be marked as serializing,
non-speculative, etc.
The "normal", aka architectural, aka FS version of the system call
instructions don't return a Fault artificially.
Change-Id: I72011a16a89332b1dcfb01c79f2f0d75c55ab773
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33281
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
isa_traits.hh used to have much more in it, but now it only has
PageShift, PageBytes, and (for now) the guest endianness. These values
should only be retrieved from the System class generally speaking, so
only the system class should include arch/isa_traits.hh.
Some gpu compute related files need PageBytes or PageShift. Even though
those files don't advertise their ISA dependence, they are tied to x86.
In those files, they can include arch/x86/isa_traits.hh.
The only other file which legitimately needs arch/isa_traits.hh is the
decoder cache since it uses PageBytes to size an array.
Change-Id: I12686368715623e3140a68a7027c136bd52567b1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33203
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This is no longer willing to implicitly cast between the locally defined
Linux::fd_set type and the system fd_set type. That's pretty reasonable
since those types are really independent of one another, and we
shouldn't be using them interchangeably in the first place. That's a
pre-existing condition though, and I just want to get the existing code
to compile for now.
Change-Id: I41d5f3695dfe5f0e406d074d31d13c6e3282df64
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33415
Reviewed-by: Ciro Santilli <ciro.santilli@arm.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
In sim/vma.hh, the include was indirectly getting the definition of
DPRINTF. It was replaced with an include of base/trace.hh which actually
provides that definition.
In the indirect branch predictor, it was being used to get the
definition of TheISA::PCState. This should come from arch/types.hh
instead.
Change-Id: I6de08f196499c85b54edde09d654902cc766c2eb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/33195
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
