prime objectives are:
o Implement a syscall path based on the epc inststruction (see
sys/ia64/ia64/syscall.s).
o Revisit the places were we need to save and restore registers
and define those contexts in terms of the register sets (see
sys/ia64/include/_regset.h).
Secundairy objectives:
o Remove the requirement to use contigmalloc for kernel stacks.
o Better handling of the high FP registers for SMP systems.
o Switch to the new cpu_switch() and cpu_throw() semantics.
o Add a good unwinder to reconstruct contexts for the rare
cases we need to (see sys/contrib/ia64/libuwx)
Many files are affected by this change. Functionally it boils
down to:
o The EPC syscall doesn't preserve registers it does not need
to preserve and places the arguments differently on the stack.
This affects libc and truss.
o The address of the kernel page directory (kptdir) had to
be unstaticized for use by the nested TLB fault handler.
The name has been changed to ia64_kptdir to avoid conflicts.
The renaming affects libkvm.
o The trapframe only contains the special registers and the
scratch registers. For syscalls using the EPC syscall path
no scratch registers are saved. This affects all places where
the trapframe is accessed. Most notably the unaligned access
handler, the signal delivery code and the debugger.
o Context switching only partly saves the special registers
and the preserved registers. This affects cpu_switch() and
triggered the move to the new semantics, which additionally
affects cpu_throw().
o The high FP registers are either in the PCB or on some
CPU. context switching for them is done lazily. This affects
trap().
o The mcontext has room for all registers, but not all of them
have to be defined in all cases. This mostly affects signal
delivery code now. The *context syscalls are as of yet still
unimplemented.
Many details went into the removal of the requirement to use
contigmalloc for kernel stacks. The details are mostly CPU
specific and limited to exception_save() and exception_restore().
The few places where we create, destroy or switch stacks were
mostly simplified by not having to construct physical addresses
and additionally saving the virtual addresses for later use.
Besides more efficient context saving and restoring, which of
course yields a noticable speedup, this also fixes the dreaded
SMP bootup problem as a side-effect. The details of which are
still not fully understood.
This change includes all the necessary backward compatibility
code to have it handle older userland binaries that use the
break instruction for syscalls. Support for break-based syscalls
has been pessimized in favor of a clean implementation. Due to
the overall better performance of the kernel, this will still
be notived as an improvement if it's noticed at all.
Approved by: re@ (jhb)
function to return the total number of CPUs and not the highest
CPU id.
o Define mp_maxid based on the minimum of the actual number of
CPUs in the system and MAXCPU.
o In cpu_mp_add, when the CPU id of the CPU we're trying to add
is larger than mp_maxid, don't add the CPU. Formerly this was
based on MAXCPU. Don't count CPUs when we add them. We already
know how many CPUs exist.
o Replace MAXCPU with mp_maxid when used in loops that iterate
over the id space. This avoids a couple of useless iterations.
o In cpu_mp_unleash, use the number of CPUs to determine if we
need to launch the CPUs.
o Remove mp_hardware as it's not used anymore.
o Move the IPI vector array from mp_machdep.c to sal.c. We use
the array as a centralized place to collect vector assignments.
Note that we still assign vectors to SMP specific IPIs in
non-SMP configurations. Rename the array from mp_ipi_vector to
ipi_vector.
o Add IPI_MCA_RENDEZ and IPI_MCA_CMCV. These are used by MCA.
Note that IPI_MCA_CMCV is not SMP specific.
o Initialize the ipi_vector array so that we place the IPIs in
sensible priority classes. The classes are relative to where
the AP wake-up vector is located to guarantee that it's the
highest priority (external) interrupt. Class assignment is
as follows:
class IPI notes
x AP wake-up (normally x=15)
x-1 MCA rendezvous
x-2 AST, Rendezvous, stop
x-3 CMCV, test
do it as a side-effect of probing for MP hardware. This allows
us to scan for local SAPICs early (especially before MBUF
initialization).
o Fix the Local SAPIC structure so that matches the Local SAPIC
table entry. Now that the Local SAPIC info is the same as the
Local APIC info, stop dumping the Local APIC entries.
o For every Local SAPIC entry in the MADT that's not disabled,
let the SMP code know about it. They represent actual CPUs.
o Register the OS_BOOT_RENDEZ entry point and provide a (bogus)
implementation for the entry point.
o Provide a mapping for internal IPI numbers to ExtINT vectors.
o In a MP system, announce the CPUs and start them by sending
IPI_AP_WAKEUP to each of them. Not that it makes a difference
at this time :-)
o Miscellaneous style fixes and other adjustments.
been made machine independent and various other adjustments have been made
to support Alpha SMP.
- It splits the per-process portions of hardclock() and statclock() off
into hardclock_process() and statclock_process() respectively. hardclock()
and statclock() call the *_process() functions for the current process so
that UP systems will run as before. For SMP systems, it is simply necessary
to ensure that all other processors execute the *_process() functions when the
main clock functions are triggered on one CPU by an interrupt. For the alpha
4100, clock interrupts are delievered in a staggered broadcast fashion, so
we simply call hardclock/statclock on the boot CPU and call the *_process()
functions on the secondaries. For x86, we call statclock and hardclock as
usual and then call forward_hardclock/statclock in the MD code to send an IPI
to cause the AP's to execute forwared_hardclock/statclock which then call the
*_process() functions.
- forward_signal() and forward_roundrobin() have been reworked to be MI and to
involve less hackery. Now the cpu doing the forward sets any flags, etc. and
sends a very simple IPI_AST to the other cpu(s). AST IPIs now just basically
return so that they can execute ast() and don't bother with setting the
astpending or needresched flags themselves. This also removes the loop in
forward_signal() as sched_lock closes the race condition that the loop worked
around.
- need_resched(), resched_wanted() and clear_resched() have been changed to take
a process to act on rather than assuming curproc so that they can be used to
implement forward_roundrobin() as described above.
- Various other SMP variables have been moved to a MI subr_smp.c and a new
header sys/smp.h declares MI SMP variables and API's. The IPI API's from
machine/ipl.h have moved to machine/smp.h which is included by sys/smp.h.
- The globaldata_register() and globaldata_find() functions as well as the
SLIST of globaldata structures has become MI and moved into subr_smp.c.
Also, the globaldata list is only available if SMP support is compiled in.
Reviewed by: jake, peter
Looked over by: eivind
not work on any real hardware (or fully work on any simulator). Much more
needs to happen before this is actually functional but its nice to see
the FreeBSD copyright message appear in the ia64 simulator.
