_mcount() stub when profiling is enabled. Emit this code sequence
for assembly routines as welli (MCOUNT definition in <machine/asm.h>.
We do not pass the GOT entry however as the 4th argument, because it's
not used. The _mcount() stub calls __mcount(), which does the actual
work. Define _MCOUNT_DECL to define __mcount. We do not have an
implementation of mcount(), so we define MCOUNT as empty, but have a
weak alias to _mcount() in _mcount.S.
Note that the _mcount() stub in the kernel is slightly different from
the stub in userland. This is because we do not have to worry about
nested routines in the kernel.
being defined, define and use a new MD macro, cpu_spinwait(). It only
expands to something on i386 and amd64, so the compiled code should be
identical.
Name of the macro found by: jhb
Reviewed by: jhb
but for CPL != 0. For some reason yet unknown it is possible for the
CPL to be 2. This would previously be counted as kernel mode, which
resulted in nasty panics. By changing the test it is now treated as
user mode, which is more correct. We still need to figure out how it
is possible that the privilege level can be 2 (or 1 for that matter),
because it's not used by us. We only use 3 (user mode) and 0 (kernel
mode).
ultimate trigger for the follow-up fixes in revisions 1.78, 1.80,
1.81 and 1.82 of trap.c. I was simply too pre-occupied with the
gateway page and how it blurs kernel space with user space and
vice versa that I couldn't see that it was all a load of bollocks.
It's not the IP address that matters, it's the privilege level that
counts. We never run in user space with lifted permissions and we
sure can not run in kernel space without it. Sure, the gateway page
is the exception, but not if you look at the privilege level. It's
user space if you run with user permissions and kernel space otherwise.
So, we're back to looking at the privilege level like it should be.
There's no other way.
Pointy hat: marcel
prototypes of cpu_halt(), cpu_reset() and swi_vm() from md_var.h to
cpu.h. This affects db_command.c and kern_shutdown.c.
ia64: move all MD prototypes from cpu.h to md_var.h. This affects
madt.c, interrupt.c and mp_machdep.c. Remove is_physical_memory().
It's not used (vm_machdep.c).
alpha: the MD prototypes have been left in cpu.h with a comment
that they should be there. Moving them is left for later. It was
expected that the impact would be significant enough to be done in
a seperate commit.
powerpc: MD prototypes left in cpu.h. Comment added.
Suggested by: bde
Tested with: make universe (pc98 incomplete)
o Remove alpha specific timer code (mc146818A) and compiled-out
calibration of said timer.
o Remove i386 inherited timer code (i8253) and related acquire and
release functions.
o Move sysbeep() from clock.c to machdep.c and have it return
ENODEV. Console beeps should be implemented using ACPI or if no
such device is described, using the sound driver.
o Move the sysctls related to adjkerntz, disable_rtc_set and
wall_cmos_clock from machdep.c to clock.c, where the variables
are.
o Don't hardcode a hz value of 1024 in cpu_initclocks() and don't
bother faking a stathz that's 1/8 of that. Keep it simple: hz
defaults to HZ and stathz equals hz. This is also how it's done
for sparc64.
o Keep a per-CPU ITC counter (pc_clock) and adjustment (pc_clockadj)
to calculate ITC skew and corrections. On average, we adjust the
ITC match register once every ~1500 interrupts for a duration of
2 consequtive interruprs. This is to correct the non-deterministic
behaviour of the ITC interrupt (there's a delay between the match
and the raising of the interrupt).
o Add 4 debugging sysctls to monitor clock behaviour. Those are
debug.clock_adjust_edges, debug.clock_adjust_excess,
debug.clock_adjust_lost and debug.clock_adjust_ticks. The first
counts the individual adjustment cycles (when the skew first
crosses the threshold), the second counts the number of times the
adjustment was excessive (any non-zero value is to be considered
a bug), the third counts lost clock interrupts and the last counts
the number of interrupts for which we applied an adjustment
(debug.clock_adjust_ticks / debug.clock_adjust_edges gives the
avarage duration of an individual adjustment -- should be ~2).
While here, remove some nearby (trivial) left-overs from alpha and
other cleanups.
always kernel space. It should be treated as user space when run with
user privileges (which is the case for the signal trampolines). This
fixes its only use in a KASSERT in subr_trap.c.
and user mode. We need to take into account that the EPC syscall path
introduces a grey area in which one can argue either way, including a
third: neither.
We now use the region in which the IP address lies. Regions 5, 6 and 7
are kernel VA regions and if the IP lies any any of those regions we
assume we're in kernel mode. Hence, we can be in kernel mode even if
we're not on the kernel stack and/or have user privileges. There're
gremlins living in the twilight zone :-)
For the EPC syscall path this particularly means that the process
leaves user mode the moment it calls into the gateway page. This
makes the most sense because from a process' point of view the call
represents a request to the kernel for some service and that service
has been performed if the call returns. With the metric we picked,
this also means that we're back in user mode IFF the call returns.
Approved by: re@ (blanket)
On alpha, PAL is involved in context management and after wiring
the CPU (in alpha_init()) a context switch was performed to tell
PAL about the context. This was bogusly brought over to ia64
where it introduced bugs, because we restored the context from
a mostly uninitialized PCB.
The cleanup constitutes:
o Remove the unused arguments from ia64_init().
o Don't return from ia64_init(), but instead call mi_startup()
directly. This reduces the amount of muckery in assembly and
also allows for the next bullet:
o Save our currect context prior to calling mi_startup(). The
reason for this is that many threads are created from thread0
by cloning the PCB. By saving our context in the PCB, we have
something sane to clone. It also ensures that a cloned thread
that does not alter the context in any way will return to
the saved context, where we're ready for the eventuality with
a nice, user unfriendly panic().
The cleanup fixes at least the following bugs:
o Entering mi_startup() with the RSE in enforced lazy mode.
o Re-execution of ia64_init() in certain "lab" conditions.
While here, add proper unwind directives to __start() so that
the unwind knows it has reached the bottom of the (call) stack.
Approved by: re@ (blanket)
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)
Add function map_port_space() to map the memory mapped I/O port
range as uncacheable virtual memory and call it prior to probing
for a console. This removes the dependency on the loader to have
done this for us. Note that this change does not include doing
the same for APs.
Approved by: re (blanket)
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
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
the process of exiting the kernel. The ast() function now loops as long
as the PS_ASTPENDING or PS_NEEDRESCHED flags are set. It returns with
preemption disabled so that any further AST's that arrive via an
interrupt will be delayed until the low-level MD code returns to user
mode.
- Use u_int's to store the tick counts for profiling purposes so that we
do not need sched_lock just to read p_sticks. This also closes a
problem where the call to addupc_task() could screw up the arithmetic
due to non-atomic reads of p_sticks.
- Axe need_proftick(), aston(), astoff(), astpending(), need_resched(),
clear_resched(), and resched_wanted() in favor of direct bit operations
on p_sflag.
- Fix up locking with sched_lock some. In addupc_intr(), use sched_lock
to ensure pr_addr and pr_ticks are updated atomically with setting
PS_OWEUPC. In ast() we clear pr_ticks atomically with clearing
PS_OWEUPC. We also do not grab the lock just to test a flag.
- Simplify the handling of Giant in ast() slightly.
Reviewed by: bde (mostly)
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
mtx_enter(lock, type) becomes:
mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)
similarily, for releasing a lock, we now have:
mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.
The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.
Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:
MTX_QUIET and MTX_NOSWITCH
The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:
mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.
Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.
Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.
Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.
Finally, caught up to the interface changes in all sys code.
Contributors: jake, jhb, jasone (in no particular order)
interrupt threads to run with it always >= 1, so that malloc can
detect M_WAITOK from "interrupt" context. This is also necessary
in order to context switch from sched_ithd() directly.
Reviewed By: peter
process is on the alternate stack or not. For compatibility
with sigstack(2) state is being updated if such is needed.
We now determine whether the process is on the alternate
stack by looking at its stack pointer. This allows a process
to siglongjmp from a signal handler on the alternate stack
to the place of the sigsetjmp on the normal stack. When
maintaining state, this would have invalidated the state
information and causing a subsequent signal to be delivered
on the normal stack instead of the alternate stack.
PR: 22286
counter register in-CPU.
This is to be used as a fast "timer", where linearity is more important
than time, and multiple lines in the linearity caused by multiple CPUs
in an SMP machine is not a problem.
This adds no code whatsoever to the FreeBSD kernel until it is actually
used, and then as a single-instruction inline routine (except for the
80386 and 80486 where it is some more inline code around nanotime(9).
Reviewed by: bde, kris, jhb
kernel backing store.
* Implement syscalls via break instructions.
* Fix backing store copying in cpu_fork() so that the child gets the right
register values.
This thing is actually starting to work now. This set of changes takes me
up to the second execve (the one which runs the first shell). Next stop
single-user mode :-).
exceptions from both kernel and user mode.
* Fix context switching so that we can switch back to a proc which we
switched away from (we were saving the state in the wrong place).
* Implement lazy switching of the high-fp state. This needs to be looked
at again for SMP to cope with the case of a process migrating from one
processor to another while it has the high-fp state.
* Make setregs() work properly. I still think this should be called
cpu_exec() or something.
* Various other minor fixes.
With this lot, we can execve() /sbin/init and we get all the way up to its
first syscall. At that point, we stop because syscall handling is not done
yet.
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.
