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Adding a few syscalls that were previously considered unimplemented.
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The ArmSystem class has a parameter to indicate whether it is
configured to use the generic timer extension or not. This parameter
doesn't affect any feature flags in the current implementation and is
therefore completely unnecessary. In fact, we usually don't set it
even if a system has a generic timer. If we ever need to check if
there is a generic timer present, we should just request a pointer and
check if it is non-null instead.
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The generic timer model currently does not support virtual
counters. Virtual and physical counters both tick with the same
frequency. However, virtual timers allow a hypervisor to set an offset
that is subtracted from the counter when it is read. This enables the
hypervisor to present a time base that ticks with virtual time in the
VM (i.e., doesn't tick when the VM isn't running). Modern Linux
kernels generally assume that virtual counters exist and try to use
them by default.
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This changeset cleans up the generic timer a bit and moves most of the
register juggling from the ISA code into a separate class in the same
source file as the rest of the generic timer. It also removes the
assumption that there is always 8 or fewer CPUs in the system. Instead
of having a fixed limit, we now instantiate per-core timers as they
are requested. This is all in preparation for other patches that add
support for virtual timers and a memory mapped interface.
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This patch ensures all page-table walks are flagged as such.
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The current ignoreWarnOnceFunc doesn't really work as expected,
since it will only generate one warning total, for whichever
"warn-once" syscall is invoked first. This patch fixes that
behavior by keeping a "warned" flag in the SyscallDesc object,
allowing suitably flagged syscalls to warn exactly once per
syscall.
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Add a missing check to ensure that exceptions are generated properly.
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We currently assume that all uncacheable memory accesses are strictly
ordered. Instead of always enforcing strict ordering, we now only
enforce it if the required memory type is device memory or strongly
ordered memory.
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The Request::UNCACHEABLE flag currently has two different
functions. The first, and obvious, function is to prevent the memory
system from caching data in the request. The second function is to
prevent reordering and speculation in CPU models.
This changeset gives the order/speculation requirement a separate flag
(Request::STRICT_ORDER). This flag prevents CPU models from doing the
following optimizations:
* Speculation: CPU models are not allowed to issue speculative
loads.
* Write combining: CPU models and caches are not allowed to merge
writes to the same cache line.
Note: The memory system may still reorder accesses unless the
UNCACHEABLE flag is set. It is therefore expected that the
STRICT_ORDER flag is combined with the UNCACHEABLE flag to prevent
this behavior.
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With the recent patches addressing how we deal with uncacheable
accesses there is no longer need for the work arounds put in place to
enforce certain sections of memory to be uncacheable during boot.
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This patch simplifies the overall CPU by changing the TLB caches such
that they do not forward snoops to the table walker port(s). Note that
only ARM and X86 are affected.
There is no reason for the ports to snoop as they do not actually take
any action, and from a performance point of view we are better of not
snooping more than we have to.
Should it at a later point be required to snoop for a particular TLB
design it is easy enough to add it back.
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This adds support for FreeBSD/aarch64 FS and SE mode (basic set of syscalls only)
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
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This patch rolls back the move of the GDB_REG_BYTES constant, and
instead adds M5_VAR_USED.
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This patch fixes a few small issues to ensure gem5 compiles when using
gcc 5.1.
First, the GDB_REG_BYTES in the RemoteGDB header are, rather
surprisingly, flagged as unused for both ARM and X86. Removing them,
however, causes compilation errors as they are actually used in the
source file. Moving the constant into the class definition fixes the
issue. Possibly a gcc bug.
Second, we have an unused EthPktData constructor using auto_ptr, and
the latter is deprecated. Since the code is never used it is simply
removed.
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This patch changes how the MMU and table walkers are created such that
a single port is used to connect the MMU and the TLBs to the memory
system. Previously two ports were needed as there are two table walker
objects (stage one and stage two), and they both had a port. Now the
port itself is moved to the Stage2MMU, and each TableWalker is simply
using the port from the parent.
By using the same port we also remove the need for having an
additional crossbar joining the two ports before the walker cache or
the L2. This simplifies the creation of the CPU cache topology in
BaseCPU.py considerably. Moreover, for naming and symmetry reasons,
the TLB walker port is connected through the stage-one table walker
thus making the naming identical to x86. Along the same line, we use
the stage-one table walker to generate the master id that is used by
all TLB-related requests.
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The ISA code sometimes stores 16-bit ASIDs as 8-bit unsigned integers
and has a couple of inverted checks that mask out the high 8 bits of
an ASID if 16-bit ASIDs have been /enabled/. This changeset fixes both
of those issues.
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We curently use INTREG_X31 instead of INTREG_SPX when accessing the
stack pointer in GDB. gem5 normally uses INTREG_SPX to access the
stack pointer, which gets mapped to the stack pointer corresponding
(INTREG_SPn) to the current exception level. This changeset updates
the GDB interface to use SPX instead of X31 (which is always zero)
when transfering CPU state to gdb.
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The remote GDB interface currently doesn't check if translations are
valid before reading memory. This causes a panic when GDB tries to
access unmapped memory (e.g., when getting a stack trace). There are
two reasons for this: 1) The function used to check for valid
translations (virtvalid()) doesn't work and panics on invalid
translations. 2) The method in the GDB interface used to test if a
translation is valid (RemoteGDB::acc) always returns true regardless
of the return from virtvalid().
This changeset fixes both of these issues.
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This changeset moves the pseudo instructions used to signal unknown
instructions and unimplemented instructions to the same source files
as the decoder fault.
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The TLB-related code is generally architecture dependent and should
live in the arch directory to signify that.
--HG--
rename : src/sim/BaseTLB.py => src/arch/generic/BaseTLB.py
rename : src/sim/tlb.cc => src/arch/generic/tlb.cc
rename : src/sim/tlb.hh => src/arch/generic/tlb.hh
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While the IsFirstMicroop flag exists it was only occasionally used in the ARM
instructions that gem5 microOps and therefore couldn't be relied on to be correct.
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This patch tidies up how we create and set the fields of a Request. In
essence it tries to use the constructor where possible (as opposed to
setPhys and setVirt), thus avoiding spreading the information across a
number of locations. In fact, setPhys is made private as part of this
patch, and a number of places where we callede setVirt instead uses
the appropriate constructor.
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added ARM aarch64 unlinkat syscall support, modeled on other <xxx>at syscalls.
This gets all of the cpu2006 int workloads passing in SE mode on aarch64.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
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This patch adds table walker stats for:
- Walk events
- Instruction vs Data
- Page size histogram
- Wait time and service time histograms
- Pending requests histogram (per cycle) - measures dist. of L
(p(1..) = how often busy, p(0) = how often idle)
- Squashes, before starting and after completion
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We currently don't handle unaligned PCs correctly. There is one check
for unaligned PCs in the TLB when running in aarch64 mode, but this
check does not cover cases where the CPU does not do a TLB lookup when
decoding an instruction (e.g., a branch stays within the same cache
line). Additionally, the Decoder class sometimes throws an assertion
for unaligned PCs which breaks speculation.
This changeset introduces a decoder fault bit field in the ExtMachInst
structure. This field can be used to signal a decoder failure. If set,
the decoder generates an internal gem5fault instruction instead of a
normal instruction. This instruction in turns either panics (fault
type PANIC), returns an PCAlignmentFault (fault type UNALIGNED,
aarch64) or PrefetchAbort (fault type UNALIGNED, aarch32).
The patch causes minor changes to the realview64 regressions, and a
stats bump will follow.
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This changeset adds more documentation to the ArmISA::Decoder class
and restructures it slightly to make API groups more obvious.
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This patch adds support for filtering events in the PMU. In order to
do so, it updates the ISADevice base class to forward an ISA pointer
to ISA devices. This enables such devices to access the MiscReg file
to determine the current execution level.
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The aarch64 system register decoder is currently not decoding
PMXEVTYPER_EL0 and PMCCFILTR_EL0 correctly. This changeset updates the
decoder so that they are decoded using the values in table C5-6 in ARM
DDI 0478A.c.
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The new single stepping implementation for x86 doesn't rely on any ISA
specific properties or functionality. This change pulls out the per ISA
implementation of those functions and promotes the X86 implementation to the
base class.
One drawback of that implementation is that the CPU might stop on an
instruction twice if it's affected by both breakpoints and single stepping.
While that might be a little surprising, it's harmless and would only happen
under somewhat unlikely circumstances.
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Not all ISAs have 64 bit sized registers, so it's not always very convenient
to access the GDB register cache in 64 bit sized chunks. This change makes it
accessible in 8, 16, 32, or 64 bit chunks. The MIPS and ARM implementations
were working around that limitation by bundling and unbundling 32 bit values
into 64 bit values. That code has been removed.
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This patch fixes a case where the Minor CPU can deadlock due to the lack
of a response to TLB request because of a bug in fault handling in the ARM
table walker.
TableWalker::processWalkWrapper is the scheduler-called wrapper which
handles deferred walks which calls to TableWalker::wait cannot immediately
process. The handling of faults generated by processWalk{AArch64,LPAE,}
calls in those two functions is is different. processWalkWrapper ignores
fault returns from processWalk... which can lead to ::finish not being
called on a translation.
This fix provides fault handling in processWalkWrapper similar to that
found in the leaf functions which BaseTLB::Translation::finish.
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This patch adds uncacheable/cacheable and read-only/read-write attributes to
the map method of PageTableBase. It also modifies the constructor of TlbEntry
structs for all architectures to consider the new attributes.
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This patch adds methods in KvmCPU model to handle KVM exits caused by syscall
instructions and page faults. These types of exits will be encountered if
KvmCPU is run in SE mode.
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Another churn to clean up undefined behaviour, mostly ARM, but some
parts also touching the generic part of the code base.
Most of the fixes are simply ensuring that proper intialisation. One
of the more subtle changes is the return type of the sign-extension,
which is changed to uint64_t. This is to avoid shifting negative
values (undefined behaviour) in the ISA code.
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regressions.
This changes the default ARM system to a Versatile Express-like system that supports
2GB of memory and PCI devices and updates the default kernels/file-systems for
AArch64 ARM systems (64-bit) to support up to 32GB of memory and PCI devices. Some
platforms that are no longer supported have been pruned from the configuration files.
In addition a set of 64-bit ARM regressions have been added to the regression system.
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Automatically extract cpu release address from DTB file.
Check SCTLR_EL1 to verify all caches are enabled.
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The checker can't verify timer registers, so it should just grab the version
from the executing CPU, otherwise it could get a larger value and diverge
execution.
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The identifier SYS_getdents is not available on Mac OS X. Therefore, its use
results in compilation failure. It seems there is no straight forward way to
implement the system call getdents using readdir() or similar C functions.
Hence the commit 6709bbcf564d is being rolled back.
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Has been tested only for alpha.
Committed by: Nilay Vaish <nilay@cs.wisc.edu>
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This patch takes quite a large step in transitioning from the ad-hoc
RefCountingPtr to the c++11 shared_ptr by adopting its use for all
Faults. There are no changes in behaviour, and the code modifications
are mostly just replacing "new" with "make_shared".
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This changeset adds probe points that can be used to implement PMU
counters for TLB stats. The following probes are supported:
* ArmISA::TLB::ppRefills / TLB Refills (TLB insertions)
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This class implements a subset of the ARM PMU v3 specification as
described in the ARMv8 reference manual. It supports most of the
features of the PMU, however the following features are known to be
missing:
* Event filtering (e.g., from different privilege levels).
* Access controls (the PMU currently ignores the execution level).
* The chain counter (event no. 0x1E) is unimplemented.
The PMU itself does not implement any events, it merely provides an
interface for the configuration scripts to hook up probes that drive
events. Configuration scripts should call addEventProbe() to configure
custom events or high-level methods to configure architected
events. The Python implementation of addEventProbe() automatically
delays event type registration until after instantiation.
In order to support CPU switching and some combined counters (e.g.,
memory references synthesized from loads and stores), the PMU allows
multiple probes per event type. When creating a system that switches
between CPU models that share the same PMU, PMU events for all of the
CPU models can be registered with the PMU.
Kudos to Matt Horsnell for the initial gem5 implementation of the PMU.
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Speculative exeuction can cause panics in detailed execution mode that
shouldn't happen.
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Some additional type checking to avoid future issues.
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