The System class has a few different arrays of values which each
correspond to a thread of execution based on their position. This
change collects them together into a single class to make managing them
easier and less error prone. It also collects methods for manipulating
those threads as an API for that class.
This class acts as a collection point for thread based state which the
System class can look into to get at all its state. It also acts as an
interface for interacting with threads for other classes. This forces
external consumers to use the API instead of accessing the individual
arrays which improves consistency.
Change-Id: Idc4575c5a0b56fe75f5c497809ad91c22bfe26cc
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25144
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
The components in base/loader were moved into a namespace called
Loader. This will make it easier to add loader components with fairly
short natural names which don't invite name collisions.
gem5 should use namespaces more in general for that reason and to make
it easier to write independent components without having to worry about
name collisions being added in the future.
Unfortunately this namespace has the same name as a class used to load
an object file into a process object. These names can be disambiguated
because the Process loader is inside the Process scope and the Loader
namespace is at global scope, but it's still confusing to read.
Fortunately, this shouldn't last for very long since the responsibility
for loading Processes is going to move to a fake OS object which will
expect to load a particular type of Process, for instance, fake 64 bit
x86 linux will load either 32 or 64 bit x86 processes.
That means that the capability to feed any binary that matches the
current build into gem5 and have gem5 figure out what to do with it
will likely be going away in the future. That's likely for the best,
since it will force users to be more explicit about what they're trying
to do, ie what OS they want to try to load a given binary, and also
will prevent loading two or more Processes which are for different OSes
to the same system, something that's possible today as far as I know
since there are no consistency checks.
Change-Id: Iea0012e98f39f5e20a7c351b78cdff9401f5e326
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24783
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Switch over to the new MemState API by specifying memory regions for
stack in each ISA, changing brkFunc to use MemState for heap memory,
and calling the MemState fixup in fixupStackFault (renamed to just
fixupFault).
Change-Id: Ie3559a68ce476daedf1a3f28b168a8fbc7face5e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25366
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Extend the MemState API to handle tracking dynamically sized memory
regions of a Process class which may be added, moved, removed, or
change in size during the course of simulation. This utilizes the
virtual memory areas (VMA) class to track individual regions and
provides a fixup method to handle physical page allocation in case of
a page fault. This allows for lazy allocation of the stack, heap, and
mmap regions of memory.
Change-Id: I3ef10657e5f8e8f0e328bdf0aa15a27b1dde39bf
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25483
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
The only functional difference between them was that the SE one might
have optionally fixed up missing translations for demand paging.
This lets us get rid of some code recreating the proxy ports in
setProcessPtr since the SE translating port no longer keeps a copy of
the process object pointer.
Change-Id: Id97df1874f1de138ffd4f2dbb5846dda79d9e4ac
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26550
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
A memory image can be described by an object file, but an object file
is more than a memory image. Also, it makes sense to manipulate a
memory image to, for instance, change how it's loaded into memory. That
takes on larger implications (relocations, the entry point, symbols,
etc.) when talking about the whole object file, and also modifies
aspects which may not need to change. For instance if an image needs
to be loaded into memory at addresses different from what's in the
object file, but other things like symbols need to stay unmodified.
Change-Id: Ia360405ffb2c1c48e0cc201ac0a0764357996a54
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21466
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
The interpreter is a separate object file, and while it's convenient to
hide loading it in the code which loads the main object file, it breaks
the conceptual abstraction since you only asked it to load the main
object file.
Also, this makes every object file format reimplement the idea of
loading the interpreter. Admittedly only ELF recognizes and sets up
an interpreter, but other formats conceptually could too.
This does move that limitted hypothetical redundancy out of the object
file formats and moves it into the process objects, but I think
conceptually that's where it belongs. It would also probably be pretty
easy to add a method to the base Process class that would handle
loading an image and also the interpreter image.
This change does not (yet) separate reading symbol tables.
Change-Id: I4a165eac599a9bcd30371a162379e833c4cc89b4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21465
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>
The ObjectFile class has hardcoded assumptions that there are three
segments, text, bss and data. There are some files which have one
"segment" like raw files, where the entire file's contents are
considered a single segment. There are also ELF files which can have
an arbitrary number of segments, and those segments can hold any
number of sections, including the text, data and/or bss sections.
Removing this assumption frees up some object file formats from having
to twist themselves to fit in that structure, possibly introducing
ambiguities when some segments may fulfill multiple roles.
Change-Id: I976e06a3a90ef852b17a6485e2595b006b2090d5
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21463
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>
ELF is, in my opinion, the most important object file format gem5
currently understands, and in ELF terminolgy the blob of data that
needs to be loaded into memory to a particular location is called a
segment. A section is a software level view of what's in a region
of memory, and a single segment may contain multiple sections which
happen to follow each other in memory.
Change-Id: Ib810c5050723d5a96bd7550515b08ac695fb1b02
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21462
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>
The AuxVector type has a bunch of accessors which just give access to
the underlying variables through references. We might as well just make
those members accessible directly.
Also, the AuxVector doesn't need to handle endianness flips itself. We
can tell the byteswap mechanism how to flip an AuxVector, and let it
handle that for us.
This gets rid of the entire .cc file which was complicated by trying
to both hide the ISA specific endianness translations, and instantiate
templated functions in a .cc.
Change-Id: I433cd61e73e0b067b6d628fba31be4a4ec1c4cf0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18373
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
AArch32 and AArch64 have different HWCAP flags in Linux, but we are
currently using AArch32 HWCAP flags to initialize the aux vector of both
AArch32 and AArch64 binaries.
This patch also fixes a bug that was introduced by running in SE mode a
target binary compiled with glibc > 2.18. Using AArch32 flags
resulted on CPUID flag being set for AArch64. This incorrectly tells
libc that emulation of the midr_el1 is supported.
In FullSystem this might work, but since we are in Syscall Emulation
there is no OS behind emulating the mrs midr_el1 instruction.
By separating AArch32 flags from AArch64 flags we are turning off the
CPUID hwcap flag in SE mode.
Change-Id: I9f651957ba9d19dc2bc06606de070c6586f0f9fa
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/12884
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Brandon Potter <Brandon.Potter@amd.com>
The AuxVector class is responsible for holding Process data.
The data that it holds is normally setup by an OS kernel in
the process address space. The purpose behind doing this is
to pass in information that the process will need for various
reasons. (Check out the enum in the header file for an idea of
what the AuxVector holds.)
The AuxVector struct was changed into a class and encapsulation
methods were added to protect access to the member variables.
The host ISA may have a different endianness than the simulated
ISA. Since data is passed between the process address space and
the simulator for auxiliary vectors, we need to worry about
maintaining endianness for the right context.
Change-Id: I32c5ac4b679559886e1efeb4b5483b92dfc94af9
Reviewed-on: https://gem5-review.googlesource.com/12109
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
Now that Nothing inherits from PageTableBase directly, it can be
merged into FuncPageTable. This change also takes the opportunity to
rename the combined class to EmulationPageTable which lets you know
that it's specifically for SE mode.
Also remove the page table entry cache since it doesn't seem to
actually improve performance. The TLBs likely absorb the majority of
the locality, essentially acting like a cache like they would in real
hardware.
Change-Id: If1bcb91aed08686603bf7bee37298c0eee826e13
Reviewed-on: https://gem5-review.googlesource.com/7342
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
When switching an assert to a fatal while addressing recent review
feedback, I forgot to reverse the polarity of the condition, making
the fatal fire in exactly the opposite of the conditions it was meant
to.
Change-Id: Icf49864ef449052bbb0d427dca786006166575c4
Reviewed-on: https://gem5-review.googlesource.com/7381
Reviewed-by: Matthias Jung <jungma@eit.uni-kl.de>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
This gets rid of an awkward NoArchPageTable class, and also gives the
arch a place to inject ISA specific parameters (specifically page size)
without having to have TheISA:: in the generic version of these types.
Change-Id: I1412f303460d5c43dafdb9b3cd07af81c908a441
Reviewed-on: https://gem5-review.googlesource.com/6981
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
These files aren't a collection of miscellaneous stuff, they're the
definition of the Logger interface, and a few utility macros for
calling into that interface (panic, warn, etc.).
Change-Id: I84267ac3f45896a83c0ef027f8f19c5e9a5667d1
Reviewed-on: https://gem5-review.googlesource.com/6226
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>
The Process class is full of implementation details and
structures related to SE Mode. This changeset factors out an
internal class from Process and moves it into a separate file.
The purpose behind doing this is to clean up the code and make
it a bit more modular.
Change-Id: Ic6941a1657751e8d51d5b6b1dcc04f1195884280
Reviewed-on: https://gem5-review.googlesource.com/2263
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Modifies the clone system call and adds execve system call. Requires allowing
processes to steal thread contexts from other processes in the same system
object and the ability to detach pieces of process state (such as MemState)
to allow dynamic sharing.
Moves aux_vector into its own .hh and .cc files just to get it out of the
already crowded Process files. Arguably, it could stay there, but it's
probably better just to move it and give it files.
The changeset looks ugly around the Process header file, but the goal here is
to move methods and members around so that they're not defined randomly
throughout the entire header file. I expect this is likely one of the reasons
why I several unused variables related to this class. So, the methods are
declared first followed by members. I've tried to aggregate them together
so that similar entries reside near one another.
There are other changes coming to this code so this is by no means the
final product.
The EIOProcess class was removed recently and it was the only other class
which derived from Process. Since every Process invocation is also a
LiveProcess invocation, it makes sense to simplify the organization by
combining the fields from LiveProcess into Process.
Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.
The mmapGrowsDown() method was a static method on the OperatingSystem
class (and derived classes), which worked OK for the templated syscall
emulation methods, but made it hard to access elsewhere. This patch
moves the method to be a virtual function on the LiveProcess method,
where it can be overridden for specific platforms (for now, Alpha).
This patch also changes the value of mmapGrowsDown() from being false
by default and true only on X86Linux32 to being true by default and
false only on Alpha, which seems closer to reality (though in reality
most people use ASLR and this doesn't really matter anymore).
In the process, also got rid of the unused mmap_start field on
LiveProcess and OperatingSystem mmapGrowsUp variable.
This patch prunes unused values, and also unifies how the values are
defined (not using an enum for ALPHA), aligning the use of int vs Addr
etc.
The patch also removes the duplication of PageBytes/PageShift and
VMPageSize/LogVMPageSize. For all ISAs the two pairs had identical
values and the latter has been removed.
Note: AArch64 and AArch32 interworking is not supported. If you use an AArch64
kernel you are restricted to AArch64 user-mode binaries. This will be addressed
in a later patch.
Note: Virtualization is only supported in AArch32 mode. This will also be fixed
in a later patch.
Contributors:
Giacomo Gabrielli (TrustZone, LPAE, system-level AArch64, AArch64 NEON, validation)
Thomas Grocutt (AArch32 Virtualization, AArch64 FP, validation)
Mbou Eyole (AArch64 NEON, validation)
Ali Saidi (AArch64 Linux support, code integration, validation)
Edmund Grimley-Evans (AArch64 FP)
William Wang (AArch64 Linux support)
Rene De Jong (AArch64 Linux support, performance opt.)
Matt Horsnell (AArch64 MP, validation)
Matt Evans (device models, code integration, validation)
Chris Adeniyi-Jones (AArch64 syscall-emulation)
Prakash Ramrakhyani (validation)
Dam Sunwoo (validation)
Chander Sudanthi (validation)
Stephan Diestelhorst (validation)
Andreas Hansson (code integration, performance opt.)
Eric Van Hensbergen (performance opt.)
Gabe Black
This patch is adding a clearer design intent to all objects that would
not be complete without a port proxy by making the proxies members
rathen than dynamically allocated. In essence, if NULL would not be a
valid value for the proxy, then we avoid using a pointer to make this
clear.
The same approach is used for the methods using these proxies, such as
loadSections, that now use references rather than pointers to better
reflect the fact that NULL would not be an acceptable value (in fact
the code would break and that is how this patch started out).
Overall the concept of "using a reference to express unconditional
composition where a NULL pointer is never valid" could be done on a
much broader scale throughout the code base, but for now it is only
done in the locations affected by the proxies.
Port proxies are used to replace non-structural ports, and thus enable
all ports in the system to correspond to a structural entity. This has
the advantage of accessing memory through the normal memory subsystem
and thus allowing any constellation of distributed memories, address
maps, etc. Most accesses are done through the "system port" that is
used for loading binaries, debugging etc. For the entities that belong
to the CPU, e.g. threads and thread contexts, they wrap the CPU data
port in a port proxy.
The following replacements are made:
FunctionalPort > PortProxy
TranslatingPort > SETranslatingPortProxy
VirtualPort > FSTranslatingPortProxy
--HG--
rename : src/mem/vport.cc => src/mem/fs_translating_port_proxy.cc
rename : src/mem/vport.hh => src/mem/fs_translating_port_proxy.hh
rename : src/mem/translating_port.cc => src/mem/se_translating_port_proxy.cc
rename : src/mem/translating_port.hh => src/mem/se_translating_port_proxy.hh
PageTable supported an allocate() call that called back
through the Process to allocate memory, but did not have
a method to map addresses without allocating new pages.
It makes more sense for Process to do the allocation, so
this method was renamed allocateMem() and moved to Process,
and uses a new map() call on PageTable.
The remaining uses of the process pointer in PageTable
were only to get the name and the PID, so by passing these
in directly in the constructor, we can make PageTable
completely independent of Process.
At the same time, rename the trace flags to debug flags since they
have broader usage than simply tracing. This means that
--trace-flags is now --debug-flags and --trace-help is now --debug-help
This change is a low level and pervasive reorganization of how PCs are managed
in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about,
the PC and the NPC, and the lsb of the PC signaled whether or not you were in
PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next
micropc, x86 and ARM introduced variable length instruction sets, and ARM
started to keep track of mode bits in the PC. Each CPU model handled PCs in
its own custom way that needed to be updated individually to handle the new
dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack,
the complexity could be hidden in the ISA at the ISA implementation's expense.
Areas like the branch predictor hadn't been updated to handle branch delay
slots or micropcs, and it turns out that had introduced a significant (10s of
percent) performance bug in SPARC and to a lesser extend MIPS. Rather than
perpetuate the problem by reworking O3 again to handle the PC features needed
by x86, this change was introduced to rework PC handling in a more modular,
transparent, and hopefully efficient way.
PC type:
Rather than having the superset of all possible elements of PC state declared
in each of the CPU models, each ISA defines its own PCState type which has
exactly the elements it needs. A cross product of canned PCState classes are
defined in the new "generic" ISA directory for ISAs with/without delay slots
and microcode. These are either typedef-ed or subclassed by each ISA. To read
or write this structure through a *Context, you use the new pcState() accessor
which reads or writes depending on whether it has an argument. If you just
want the address of the current or next instruction or the current micro PC,
you can get those through read-only accessors on either the PCState type or
the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the
move away from readPC. That name is ambiguous since it's not clear whether or
not it should be the actual address to fetch from, or if it should have extra
bits in it like the PAL mode bit. Each class is free to define its own
functions to get at whatever values it needs however it needs to to be used in
ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the
PC and into a separate field like ARM.
These types can be reset to a particular pc (where npc = pc +
sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as
appropriate), printed, serialized, and compared. There is a branching()
function which encapsulates code in the CPU models that checked if an
instruction branched or not. Exactly what that means in the context of branch
delay slots which can skip an instruction when not taken is ambiguous, and
ideally this function and its uses can be eliminated. PCStates also generally
know how to advance themselves in various ways depending on if they point at
an instruction, a microop, or the last microop of a macroop. More on that
later.
Ideally, accessing all the PCs at once when setting them will improve
performance of M5 even though more data needs to be moved around. This is
because often all the PCs need to be manipulated together, and by getting them
all at once you avoid multiple function calls. Also, the PCs of a particular
thread will have spatial locality in the cache. Previously they were grouped
by element in arrays which spread out accesses.
Advancing the PC:
The PCs were previously managed entirely by the CPU which had to know about PC
semantics, try to figure out which dimension to increment the PC in, what to
set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction
with the PC type itself. Because most of the information about how to
increment the PC (mainly what type of instruction it refers to) is contained
in the instruction object, a new advancePC virtual function was added to the
StaticInst class. Subclasses provide an implementation that moves around the
right element of the PC with a minimal amount of decision making. In ISAs like
Alpha, the instructions always simply assign NPC to PC without having to worry
about micropcs, nnpcs, etc. The added cost of a virtual function call should
be outweighed by not having to figure out as much about what to do with the
PCs and mucking around with the extra elements.
One drawback of making the StaticInsts advance the PC is that you have to
actually have one to advance the PC. This would, superficially, seem to
require decoding an instruction before fetch could advance. This is, as far as
I can tell, realistic. fetch would advance through memory addresses, not PCs,
perhaps predicting new memory addresses using existing ones. More
sophisticated decisions about control flow would be made later on, after the
instruction was decoded, and handed back to fetch. If branching needs to
happen, some amount of decoding needs to happen to see that it's a branch,
what the target is, etc. This could get a little more complicated if that gets
done by the predecoder, but I'm choosing to ignore that for now.
Variable length instructions:
To handle variable length instructions in x86 and ARM, the predecoder now
takes in the current PC by reference to the getExtMachInst function. It can
modify the PC however it needs to (by setting NPC to be the PC + instruction
length, for instance). This could be improved since the CPU doesn't know if
the PC was modified and always has to write it back.
ISA parser:
To support the new API, all PC related operand types were removed from the
parser and replaced with a PCState type. There are two warts on this
implementation. First, as with all the other operand types, the PCState still
has to have a valid operand type even though it doesn't use it. Second, using
syntax like PCS.npc(target) doesn't work for two reasons, this looks like the
syntax for operand type overriding, and the parser can't figure out if you're
reading or writing. Instructions that use the PCS operand (which I've
consistently called it) need to first read it into a local variable,
manipulate it, and then write it back out.
Return address stack:
The return address stack needed a little extra help because, in the presence
of branch delay slots, it has to merge together elements of the return PC and
the call PC. To handle that, a buildRetPC utility function was added. There
are basically only two versions in all the ISAs, but it didn't seem short
enough to put into the generic ISA directory. Also, the branch predictor code
in O3 and InOrder were adjusted so that they always store the PC of the actual
call instruction in the RAS, not the next PC. If the call instruction is a
microop, the next PC refers to the next microop in the same macroop which is
probably not desirable. The buildRetPC function advances the PC intelligently
to the next macroop (in an ISA specific way) so that that case works.
Change in stats:
There were no change in stats except in MIPS and SPARC in the O3 model. MIPS
runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could
likely be improved further by setting call/return instruction flags and taking
advantage of the RAS.
TODO:
Add != operators to the PCState classes, defined trivially to be !(a==b).
Smooth out places where PCs are split apart, passed around, and put back
together later. I think this might happen in SPARC's fault code. Add ISA
specific constructors that allow setting PC elements without calling a bunch
of accessors. Try to eliminate the need for the branching() function. Factor
out Alpha's PAL mode pc bit into a separate flag field, and eliminate places
where it's blindly masked out or tested in the PC.
