syscall_emul: [patch 13/22] add system call retry capability

This changeset adds functionality that allows system calls to retry without
affecting thread context state such as the program counter or register values
for the associated thread context (when system calls return with a retry
fault).

This functionality is needed to solve problems with blocking system calls
in multi-process or multi-threaded simulations where information is passed
between processes/threads. Blocking system calls can cause deadlock because
the simulator itself is single threaded. There is only a single thread
servicing the event queue which can cause deadlock if the thread hits a
blocking system call instruction.

To illustrate the problem, consider two processes using the producer/consumer
sharing model. The processes can use file descriptors and the read and write
calls to pass information to one another. If the consumer calls the blocking
read system call before the producer has produced anything, the call will
block the event queue (while executing the system call instruction) and
deadlock the simulation.

The solution implemented in this changeset is to recognize that the system
calls will block and then generate a special retry fault. The fault will
be sent back up through the function call chain until it is exposed to the
cpu model's pipeline where the fault becomes visible. The fault will trigger
the cpu model to replay the instruction at a future tick where the call has
a chance to succeed without actually going into a blocking state.

In subsequent patches, we recognize that a syscall will block by calling a
non-blocking poll (from inside the system call implementation) and checking
for events. When events show up during the poll, it signifies that the call
would not have blocked and the syscall is allowed to proceed (calling an
underlying host system call if necessary). If no events are returned from the
poll, we generate the fault and try the instruction for the thread context
at a distant tick. Note that retrying every tick is not efficient.

As an aside, the simulator has some multi-threading support for the event
queue, but it is not used by default and needs work. Even if the event queue
was completely multi-threaded, meaning that there is a hardware thread on
the host servicing a single simulator thread contexts with a 1:1 mapping
between them, it's still possible to run into deadlock due to the event queue
barriers on quantum boundaries. The solution of replaying at a later tick
is the simplest solution and solves the problem generally.

syscall_emul: [patch 5/22] remove LiveProcess class and use Process instead

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.

SPARC: Clean up some historical style issues.

SE mode: Make keeping track of the number of syscalls less hacky.

Processes: Make getting and setting system call arguments part of a process object.

Make the process objects use the Params structs in their constructors, and use a limit to check if access are on the stack.

Split the syscall table, SPARC specific syscall implementations, and the 32 bit syscall table into it's own file. Corrected problems with the stat structure. These should be tested on 64 bit x86 and SPARC machines.

Make trap instructions always generate TrapInstruction Fault objects which call into the Process object to handle system calls. Refactored the Process objects, and move the handler code into it's own file, and add some syscalls which are used in a natively compiled hello world. Software traps with trap number 3 (not syscall number 3) are supposed to cause the register windows to be flushed but are ignored right now. Finally, made uname for SPARC report a 2.6.12 kernel which is what m22-018.pool happens to be running.

Implement current working directory for LiveProcesses

Finished changing how stat structures are translated, fixed the handling of various ids as LiveProcess parameters.

src/arch/alpha/linux/process.cc:
src/arch/alpha/linux/process.hh:
src/arch/alpha/process.cc:
src/arch/alpha/process.hh:
src/arch/alpha/tru64/process.cc:
src/arch/alpha/tru64/process.hh:
src/arch/mips/linux/process.cc:
src/arch/mips/linux/process.hh:
src/arch/mips/process.cc:
src/arch/mips/process.hh:
src/arch/sparc/linux/process.cc:
src/arch/sparc/linux/process.hh:
src/arch/sparc/process.cc:
src/arch/sparc/process.hh:
src/arch/sparc/solaris/process.cc:
src/arch/sparc/solaris/process.hh:
src/sim/process.cc:
src/sim/process.hh:
src/sim/syscall_emul.cc:
src/sim/syscall_emul.hh:
Changed Process to LiveProcess in syscall handlers and fixed the implementation of uid, euid, gid, egid, pid and ppid as LiveProcess parameters.
src/kern/tru64/tru64.hh:
Changed Process to LiveProcess in syscall handlers and fixed the implementation of uid, euid, gid, egid, pid and ppid as LiveProcess parameters. Also fit tru64 in with the new way to handle stat calls.

Cleaned up include files and got rid of many using directives in header files.

Change ExecContext to ThreadContext. This is being renamed to differentiate between the interface used objects outside of the CPU, and the interface used by the ISA. ThreadContext is used by objects outside of the CPU and is specifically defined in thread_context.hh. ExecContext is more implicit, and is defined by files such as base_dyn_inst.hh or cpu/simple/base.hh.

Further renames/reorganization will be coming shortly; what is currently CPUExecContext (the old ExecContext from m5) will be renamed to SimpleThread or something similar.

src/arch/alpha/arguments.cc:
src/arch/alpha/arguments.hh:
src/arch/alpha/ev5.cc:
src/arch/alpha/faults.cc:
src/arch/alpha/faults.hh:
src/arch/alpha/freebsd/system.cc:
src/arch/alpha/freebsd/system.hh:
src/arch/alpha/isa/branch.isa:
src/arch/alpha/isa/decoder.isa:
src/arch/alpha/isa/main.isa:
src/arch/alpha/linux/process.cc:
src/arch/alpha/linux/system.cc:
src/arch/alpha/linux/system.hh:
src/arch/alpha/linux/threadinfo.hh:
src/arch/alpha/process.cc:
src/arch/alpha/regfile.hh:
src/arch/alpha/stacktrace.cc:
src/arch/alpha/stacktrace.hh:
src/arch/alpha/tlb.cc:
src/arch/alpha/tlb.hh:
src/arch/alpha/tru64/process.cc:
src/arch/alpha/tru64/system.cc:
src/arch/alpha/tru64/system.hh:
src/arch/alpha/utility.hh:
src/arch/alpha/vtophys.cc:
src/arch/alpha/vtophys.hh:
src/arch/mips/faults.cc:
src/arch/mips/faults.hh:
src/arch/mips/isa_traits.cc:
src/arch/mips/isa_traits.hh:
src/arch/mips/linux/process.cc:
src/arch/mips/process.cc:
src/arch/mips/regfile/float_regfile.hh:
src/arch/mips/regfile/int_regfile.hh:
src/arch/mips/regfile/misc_regfile.hh:
src/arch/mips/regfile/regfile.hh:
src/arch/mips/stacktrace.hh:
src/arch/sparc/faults.cc:
src/arch/sparc/faults.hh:
src/arch/sparc/isa_traits.hh:
src/arch/sparc/linux/process.cc:
src/arch/sparc/linux/process.hh:
src/arch/sparc/process.cc:
src/arch/sparc/regfile.hh:
src/arch/sparc/solaris/process.cc:
src/arch/sparc/stacktrace.hh:
src/arch/sparc/ua2005.cc:
src/arch/sparc/utility.hh:
src/arch/sparc/vtophys.cc:
src/arch/sparc/vtophys.hh:
src/base/remote_gdb.cc:
src/base/remote_gdb.hh:
src/cpu/base.cc:
src/cpu/base.hh:
src/cpu/base_dyn_inst.hh:
src/cpu/checker/cpu.cc:
src/cpu/checker/cpu.hh:
src/cpu/checker/exec_context.hh:
src/cpu/cpu_exec_context.cc:
src/cpu/cpu_exec_context.hh:
src/cpu/cpuevent.cc:
src/cpu/cpuevent.hh:
src/cpu/exetrace.hh:
src/cpu/intr_control.cc:
src/cpu/memtest/memtest.hh:
src/cpu/o3/alpha_cpu.hh:
src/cpu/o3/alpha_cpu_impl.hh:
src/cpu/o3/alpha_dyn_inst_impl.hh:
src/cpu/o3/commit.hh:
src/cpu/o3/commit_impl.hh:
src/cpu/o3/cpu.cc:
src/cpu/o3/cpu.hh:
src/cpu/o3/fetch_impl.hh:
src/cpu/o3/regfile.hh:
src/cpu/o3/thread_state.hh:
src/cpu/ozone/back_end.hh:
src/cpu/ozone/cpu.hh:
src/cpu/ozone/cpu_impl.hh:
src/cpu/ozone/front_end.hh:
src/cpu/ozone/front_end_impl.hh:
src/cpu/ozone/inorder_back_end.hh:
src/cpu/ozone/lw_back_end.hh:
src/cpu/ozone/lw_back_end_impl.hh:
src/cpu/ozone/lw_lsq.hh:
src/cpu/ozone/lw_lsq_impl.hh:
src/cpu/ozone/thread_state.hh:
src/cpu/pc_event.cc:
src/cpu/pc_event.hh:
src/cpu/profile.cc:
src/cpu/profile.hh:
src/cpu/quiesce_event.cc:
src/cpu/quiesce_event.hh:
src/cpu/simple/atomic.cc:
src/cpu/simple/base.cc:
src/cpu/simple/base.hh:
src/cpu/simple/timing.cc:
src/cpu/static_inst.cc:
src/cpu/static_inst.hh:
src/cpu/thread_state.hh:
src/dev/alpha_console.cc:
src/dev/ns_gige.cc:
src/dev/sinic.cc:
src/dev/tsunami_cchip.cc:
src/kern/kernel_stats.cc:
src/kern/kernel_stats.hh:
src/kern/linux/events.cc:
src/kern/linux/events.hh:
src/kern/system_events.cc:
src/kern/system_events.hh:
src/kern/tru64/dump_mbuf.cc:
src/kern/tru64/tru64.hh:
src/kern/tru64/tru64_events.cc:
src/kern/tru64/tru64_events.hh:
src/mem/vport.cc:
src/mem/vport.hh:
src/sim/faults.cc:
src/sim/faults.hh:
src/sim/process.cc:
src/sim/process.hh:
src/sim/pseudo_inst.cc:
src/sim/pseudo_inst.hh:
src/sim/syscall_emul.cc:
src/sim/syscall_emul.hh:
src/sim/system.cc:
src/cpu/thread_context.hh:
src/sim/system.hh:
src/sim/vptr.hh:
Change ExecContext to ThreadContext.

Updated Authors from bk prs info

New directory structure:
- simulator source now in 'src' subdirectory
- imported files from 'ext' repository
- support building in arbitrary places, including
outside of the source tree. See comment at top
of SConstruct file for more details.
Regression tests are temporarily disabled; that
syetem needs more extensive revisions.

SConstruct:
Update for new directory structure.
Modify to support build trees that are not subdirectories
of the source tree. See comment at top of file for
more details.
Regression tests are temporarily disabled.
src/arch/SConscript:
src/arch/isa_parser.py:
src/python/SConscript:
Update for new directory structure.