Arrange to update cached LWP credentials in userret() rather than during
syscall/trap entry, eliminating a test+branch on every syscall/trap.

This wasn't possible in the 3.99.x timeframe when l->l_cred came about
because there wasn't a reliable/timely way to force an ONPROC LWP running on
a remote CPU into the kernel (which is just about the only new thing in
this scheme).

Drop unused opt_altivec.h and opt_multiprocessor.h.

Style and cosmetic changes. No binary changes intended.

Centralized shared part of child_return() into MI part

Add a new function md_child_return() for MD specific bits only.

New child_return() is now part of MI and central code that handles
uniformly tracing code (KTR and ptrace(2)).

Synchronize value passed to ktrsysret() among ports to SYS_fork. This is
a traditional value and accessing p_lflag to check for PL_PPWAIT shall
use locking against proc_lock. Returning SYS_fork vs SYS_vfork still isn't
correct enough as there are more entry points to forking code. Instead of
making it too good, just settle with plain SYS_fork for all ports.

Rework the fork(2)/vfork(2) event signalling under ptrace(2)

Remove the constraint of SIGTRAP event being maskable by a tracee.

Now all SIGTRAP TRAP_CHLD events are delivered to debugger.

This code touches MD specific logic and the child_return routine.
It's an intermediate step with a room for refactoring in future and
right now the least invasive approach. This allows to assert expected
behavior in already existing ATF tests and make the code prettier
in future keeping the same semantics. Probably there is a need for a MI
wrapper of child_return for shared functionality between ports.

branches: 1.53.30;
- remove set but unused variables

branches: 1.52.2;
Use sy_invoke

branches: 1.51.2;
Use the new syscall approach by collapsing fancy/plain variants into just
a single routine.

Remove COMPAT_SA / KERN_SA. Welcome to 6.99.3!
Approved by core@.

Remove white-spaces.

branches: 1.48.4; 1.48.8;
Remove Darwin, MACH and Mach-O support.

Use l->l_md.md_utf in preference to trapframe(l). This shrink the kernel
just a bit in size.

Add support for BookE Freescale MPC85xx (e500 core) processors.
Add fast softint support for PowerPC (though only booke uses it).
Redo FPU/VEC support and add e500 SPE support.
Rework trap/intrs to use a common trapframe format.
Support SOFTFLOAT (no hardfloat or fpu emulation) for BookE.

branches: 1.45.2;
Retire struct user, remove sys/user.h inclusions. Note sys/user.h header
as obsolete. Remove USER_TO_UAREA/UAREA_TO_USER macros.

Various #include fixes and review by matt@.

branches: 1.44.4;
Use lwp_getpcb() on mips, powerpc and sh3, clean from struct user usage.

branches: 1.43.16;
Provide a small inline wrapper for sysent::sy_call() and use it to store
the active syscall description in struct lwp. To be used at some future
point to prevent unloading of modules that provide syscalls, while the
syscalls are in use.

Merge wrstuden-revivesa into HEAD.

branches: 1.41.2; 1.41.4; 1.41.8;
- Retire SYCALL_MPSAFE. With the exceptions of darwin and irix emulations,
all system calls are now MPSAFE.
- Remove unneeded acquire/release of kernel_lock.

branches: 1.40.6; 1.40.8;
narg -> sy_narg

Remove the 'args' parameter to 'trace_exit()' it is no longer used.
Instead of passing the (un)real system call code and syscall table pointer,
just pass the number of arguments - which is what ktrace really wants.
Ride forthcoming 4.99.53

Don't pass 'curlwp' into trace_enter() and trace_exit().

Merge vmlocking2 to head.

branches: 1.36.2; 1.36.4; 1.36.8;
Don't set l_usrpri / spc_curpriority here. mi_userret() does it.

Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree. Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches. The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

branches: 1.34.2; 1.34.6;
Changes to make ktrace LKM friendly and reduce ifdef KTRACE. Proposed
on tech-kern.

branches: 1.33.2; 1.33.10; 1.33.14; 1.33.18;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.32.2;
Merge newlock2 to head.

branches: 1.31.4;
- Hold a reference to the process credentials in each struct lwp.
- Update the reference on syscall and user trap if p_cred has changed.
- Collect accounting flags in the LWP, and collate on LWP exit.

branches: 1.30.2;
Clean up fallout proc_is_traced_p() change:
- proc_is_traced_p() -> trace_is_enabled(), to match trace_enter() and
trace_exit().
- trace_is_enabled() becomes a real function.
- Remove unnecessary include files from various files that used to care
about KTRACE and SYSTRACE, but do no more.

syscall_fancy is only defined if either KTRACE or SYSTRACE is set,
so enclose its use in the same set of conditionals.

Always define syscall_fancy.

Add a proc_is_traced_p() macro and use it, instead of copying the same code
in many places. Idea from thorpej.

branches: 1.26.2;
implement PT_SYSCALL

branches: 1.25.4; 1.25.6;
merge ktrace-lwp.

branches: 1.24.2;
PR/29607: Christian Biere systrace doesn't handle interrupted syscalls properly
Instead of jumping to the default "bad" case, jump to the error handling
switch, so that we can deal with ERESTART/EJUSTRETURN properly.

Don't pass the (unused) return value args to the
trace_enter()/systrace_enter() functions.

Back out rev 1.19. It's wrong. Add comments so it doesn't happen again.

branches: 1.21.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

Make sure to include opt_foo.h if a defflag option FOO is used.

Merge the nathanw_sa branch.

Pass the system call table to trace_enter() and ktrsys() so that it is
possible to use alternate system call tables. This is usefull for
displaying correctly the arguments in Mach binaries traces.

If NULL is given, then the regular systam call table for the process is used.

The recent mach trap support caused indirect system calls (a la syscall(2))
to be incorectly recorded as 'syscall'. Fix this.

Darwin skips the next instruction after a successful system call. Strange
world.

Add a realcode argument to trace_enter and ktrsyscall. realcode is the
original system call number, which can be negative for a Mach trap.
We cannot just replace code by realcode, because ktrsyscall uses it as
an index in the system call table, thus crashing the kernel when the
value is negative.

Change syscall to bound code so that systrace and ktrace won't fall off
the end of a table. XXX this is wrong since code does not indicate the
sysent table for which code was used as an index.

Get rid of nsysent. Use EMULNAMEU to use the appropriate constant.
Revamp the mach_syscall_dispatch function to be much simplier (pass in
a syscall code and return a const struct sysent * pointer).

Added support for Darwin's PowerPC-only system calls:
ppccalls, with system call numbers starting at 0x6000
fasttraps, with system call numbers starting at 0x7FF0

Because the Mach system call dispatching code has grown a bit
too much, introduce an inline function to handle it (mach_syscall_dispatch).

While we are there, remove the Mach and Linux includes from
arch/powerpc/powerpc/syscall.c and push them into
arch/powerpc/powerpc/{mach|linux}_syscall.c

back previous revision 1.9 off - compat code was changed to set
struct emul e_nsysent to *SYS_NSYSENT now, and the mask is more efficient

In struct emul, e_nsysent is *not* initialized to *SYS_NSYSENT but
*SYS_MAXSYSCALL. Adjust to this and simply compare 'code' to it instead
of doing the p-o-2 dance.

Move child_return back to syscall.c
Fix syscall to use emulations SYS_syscall/SYS___syscall definitions.
Use the emulation NSYSENT to limit code.
Don't define *syscall_fancy if it will never be used.

Fixed mistakes

Add COMPAT_MACH and EXEC_MACHO support on the PowerPC

Prepare syscall.c for COMPAT_MACH support. linux_syscall_intern is
moved to a Linux specific file, child_return is moved to trap.c,
and we introduce a EMULNAME macro co that syscall.c can be included to
define the system call handler for another emulation.

branches: 1.4.2;
use a completely separate trap handler for syscall traps.
this reduces syscall overhead by 10% to 20% depending on cpu type.

branches: 1.3.2;
create a syscall_plain() like on other platforms
and avoid getting the kernel lock for MPSAFE syscalls.

branches: 1.2.2;
Add a linux_syscall_intern entry (appropriately ifdef'ed COMPAT_LINUX).
When/if PPC ever supports LKMs, this should be moved to a separate file.

Add common syscall dispatcher. Also put child_return in here.

Drop unused opt_altivec.h and opt_multiprocessor.h.

Style and cosmetic changes. No binary changes intended.

Centralized shared part of child_return() into MI part

Add a new function md_child_return() for MD specific bits only.

New child_return() is now part of MI and central code that handles
uniformly tracing code (KTR and ptrace(2)).

Synchronize value passed to ktrsysret() among ports to SYS_fork. This is
a traditional value and accessing p_lflag to check for PL_PPWAIT shall
use locking against proc_lock. Returning SYS_fork vs SYS_vfork still isn't
correct enough as there are more entry points to forking code. Instead of
making it too good, just settle with plain SYS_fork for all ports.

Rework the fork(2)/vfork(2) event signalling under ptrace(2)

Remove the constraint of SIGTRAP event being maskable by a tracee.

Now all SIGTRAP TRAP_CHLD events are delivered to debugger.

This code touches MD specific logic and the child_return routine.
It's an intermediate step with a room for refactoring in future and
right now the least invasive approach. This allows to assert expected
behavior in already existing ATF tests and make the code prettier
in future keeping the same semantics. Probably there is a need for a MI
wrapper of child_return for shared functionality between ports.

branches: 1.53.30;
- remove set but unused variables

branches: 1.52.2;
Use sy_invoke

branches: 1.51.2;
Use the new syscall approach by collapsing fancy/plain variants into just
a single routine.

Remove COMPAT_SA / KERN_SA. Welcome to 6.99.3!
Approved by core@.

Remove white-spaces.

branches: 1.48.4; 1.48.8;
Remove Darwin, MACH and Mach-O support.

Use l->l_md.md_utf in preference to trapframe(l). This shrink the kernel
just a bit in size.

Add support for BookE Freescale MPC85xx (e500 core) processors.
Add fast softint support for PowerPC (though only booke uses it).
Redo FPU/VEC support and add e500 SPE support.
Rework trap/intrs to use a common trapframe format.
Support SOFTFLOAT (no hardfloat or fpu emulation) for BookE.

branches: 1.45.2;
Retire struct user, remove sys/user.h inclusions. Note sys/user.h header
as obsolete. Remove USER_TO_UAREA/UAREA_TO_USER macros.

Various #include fixes and review by matt@.

branches: 1.44.4;
Use lwp_getpcb() on mips, powerpc and sh3, clean from struct user usage.

branches: 1.43.16;
Provide a small inline wrapper for sysent::sy_call() and use it to store
the active syscall description in struct lwp. To be used at some future
point to prevent unloading of modules that provide syscalls, while the
syscalls are in use.

Merge wrstuden-revivesa into HEAD.

branches: 1.41.2; 1.41.4; 1.41.8;
- Retire SYCALL_MPSAFE. With the exceptions of darwin and irix emulations,
all system calls are now MPSAFE.
- Remove unneeded acquire/release of kernel_lock.

branches: 1.40.6; 1.40.8;
narg -> sy_narg

Remove the 'args' parameter to 'trace_exit()' it is no longer used.
Instead of passing the (un)real system call code and syscall table pointer,
just pass the number of arguments - which is what ktrace really wants.
Ride forthcoming 4.99.53

Don't pass 'curlwp' into trace_enter() and trace_exit().

Merge vmlocking2 to head.

branches: 1.36.2; 1.36.4; 1.36.8;
Don't set l_usrpri / spc_curpriority here. mi_userret() does it.

Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree. Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches. The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

branches: 1.34.2; 1.34.6;
Changes to make ktrace LKM friendly and reduce ifdef KTRACE. Proposed
on tech-kern.

branches: 1.33.2; 1.33.10; 1.33.14; 1.33.18;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.32.2;
Merge newlock2 to head.

branches: 1.31.4;
- Hold a reference to the process credentials in each struct lwp.
- Update the reference on syscall and user trap if p_cred has changed.
- Collect accounting flags in the LWP, and collate on LWP exit.

branches: 1.30.2;
Clean up fallout proc_is_traced_p() change:
- proc_is_traced_p() -> trace_is_enabled(), to match trace_enter() and
trace_exit().
- trace_is_enabled() becomes a real function.
- Remove unnecessary include files from various files that used to care
about KTRACE and SYSTRACE, but do no more.

syscall_fancy is only defined if either KTRACE or SYSTRACE is set,
so enclose its use in the same set of conditionals.

Always define syscall_fancy.

Add a proc_is_traced_p() macro and use it, instead of copying the same code
in many places. Idea from thorpej.

branches: 1.26.2;
implement PT_SYSCALL

branches: 1.25.4; 1.25.6;
merge ktrace-lwp.

branches: 1.24.2;
PR/29607: Christian Biere systrace doesn't handle interrupted syscalls properly
Instead of jumping to the default "bad" case, jump to the error handling
switch, so that we can deal with ERESTART/EJUSTRETURN properly.

Don't pass the (unused) return value args to the
trace_enter()/systrace_enter() functions.

Back out rev 1.19. It's wrong. Add comments so it doesn't happen again.

branches: 1.21.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

Make sure to include opt_foo.h if a defflag option FOO is used.

Merge the nathanw_sa branch.

Pass the system call table to trace_enter() and ktrsys() so that it is
possible to use alternate system call tables. This is usefull for
displaying correctly the arguments in Mach binaries traces.

If NULL is given, then the regular systam call table for the process is used.

The recent mach trap support caused indirect system calls (a la syscall(2))
to be incorectly recorded as 'syscall'. Fix this.

Darwin skips the next instruction after a successful system call. Strange
world.

Add a realcode argument to trace_enter and ktrsyscall. realcode is the
original system call number, which can be negative for a Mach trap.
We cannot just replace code by realcode, because ktrsyscall uses it as
an index in the system call table, thus crashing the kernel when the
value is negative.

Change syscall to bound code so that systrace and ktrace won't fall off
the end of a table. XXX this is wrong since code does not indicate the
sysent table for which code was used as an index.

Get rid of nsysent. Use EMULNAMEU to use the appropriate constant.
Revamp the mach_syscall_dispatch function to be much simplier (pass in
a syscall code and return a const struct sysent * pointer).

Added support for Darwin's PowerPC-only system calls:
ppccalls, with system call numbers starting at 0x6000
fasttraps, with system call numbers starting at 0x7FF0

Because the Mach system call dispatching code has grown a bit
too much, introduce an inline function to handle it (mach_syscall_dispatch).

While we are there, remove the Mach and Linux includes from
arch/powerpc/powerpc/syscall.c and push them into
arch/powerpc/powerpc/{mach|linux}_syscall.c

back previous revision 1.9 off - compat code was changed to set
struct emul e_nsysent to *SYS_NSYSENT now, and the mask is more efficient

In struct emul, e_nsysent is *not* initialized to *SYS_NSYSENT but
*SYS_MAXSYSCALL. Adjust to this and simply compare 'code' to it instead
of doing the p-o-2 dance.

Move child_return back to syscall.c
Fix syscall to use emulations SYS_syscall/SYS___syscall definitions.
Use the emulation NSYSENT to limit code.
Don't define *syscall_fancy if it will never be used.

Fixed mistakes

Add COMPAT_MACH and EXEC_MACHO support on the PowerPC

Prepare syscall.c for COMPAT_MACH support. linux_syscall_intern is
moved to a Linux specific file, child_return is moved to trap.c,
and we introduce a EMULNAME macro co that syscall.c can be included to
define the system call handler for another emulation.

branches: 1.4.2;
use a completely separate trap handler for syscall traps.
this reduces syscall overhead by 10% to 20% depending on cpu type.

branches: 1.3.2;
create a syscall_plain() like on other platforms
and avoid getting the kernel lock for MPSAFE syscalls.

branches: 1.2.2;
Add a linux_syscall_intern entry (appropriately ifdef'ed COMPAT_LINUX).
When/if PPC ever supports LKMs, this should be moved to a separate file.

Add common syscall dispatcher. Also put child_return in here.

Centralized shared part of child_return() into MI part

Add a new function md_child_return() for MD specific bits only.

New child_return() is now part of MI and central code that handles
uniformly tracing code (KTR and ptrace(2)).

Synchronize value passed to ktrsysret() among ports to SYS_fork. This is
a traditional value and accessing p_lflag to check for PL_PPWAIT shall
use locking against proc_lock. Returning SYS_fork vs SYS_vfork still isn't
correct enough as there are more entry points to forking code. Instead of
making it too good, just settle with plain SYS_fork for all ports.

Rework the fork(2)/vfork(2) event signalling under ptrace(2)

Remove the constraint of SIGTRAP event being maskable by a tracee.

Now all SIGTRAP TRAP_CHLD events are delivered to debugger.

This code touches MD specific logic and the child_return routine.
It's an intermediate step with a room for refactoring in future and
right now the least invasive approach. This allows to assert expected
behavior in already existing ATF tests and make the code prettier
in future keeping the same semantics. Probably there is a need for a MI
wrapper of child_return for shared functionality between ports.

- remove set but unused variables

branches: 1.52.2;
Use sy_invoke

branches: 1.51.2;
Use the new syscall approach by collapsing fancy/plain variants into just
a single routine.

Remove COMPAT_SA / KERN_SA. Welcome to 6.99.3!
Approved by core@.

Remove white-spaces.

branches: 1.48.4; 1.48.8;
Remove Darwin, MACH and Mach-O support.

Use l->l_md.md_utf in preference to trapframe(l). This shrink the kernel
just a bit in size.

Add support for BookE Freescale MPC85xx (e500 core) processors.
Add fast softint support for PowerPC (though only booke uses it).
Redo FPU/VEC support and add e500 SPE support.
Rework trap/intrs to use a common trapframe format.
Support SOFTFLOAT (no hardfloat or fpu emulation) for BookE.

branches: 1.45.2;
Retire struct user, remove sys/user.h inclusions. Note sys/user.h header
as obsolete. Remove USER_TO_UAREA/UAREA_TO_USER macros.

Various #include fixes and review by matt@.

branches: 1.44.4;
Use lwp_getpcb() on mips, powerpc and sh3, clean from struct user usage.

branches: 1.43.16;
Provide a small inline wrapper for sysent::sy_call() and use it to store
the active syscall description in struct lwp. To be used at some future
point to prevent unloading of modules that provide syscalls, while the
syscalls are in use.

Merge wrstuden-revivesa into HEAD.

branches: 1.41.2; 1.41.4; 1.41.8;
- Retire SYCALL_MPSAFE. With the exceptions of darwin and irix emulations,
all system calls are now MPSAFE.
- Remove unneeded acquire/release of kernel_lock.

branches: 1.40.6; 1.40.8;
narg -> sy_narg

Remove the 'args' parameter to 'trace_exit()' it is no longer used.
Instead of passing the (un)real system call code and syscall table pointer,
just pass the number of arguments - which is what ktrace really wants.
Ride forthcoming 4.99.53

Don't pass 'curlwp' into trace_enter() and trace_exit().

Merge vmlocking2 to head.

branches: 1.36.2; 1.36.4; 1.36.8;
Don't set l_usrpri / spc_curpriority here. mi_userret() does it.

Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree. Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches. The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

branches: 1.34.2; 1.34.6;
Changes to make ktrace LKM friendly and reduce ifdef KTRACE. Proposed
on tech-kern.

branches: 1.33.2; 1.33.10; 1.33.14; 1.33.18;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.32.2;
Merge newlock2 to head.

branches: 1.31.4;
- Hold a reference to the process credentials in each struct lwp.
- Update the reference on syscall and user trap if p_cred has changed.
- Collect accounting flags in the LWP, and collate on LWP exit.

branches: 1.30.2;
Clean up fallout proc_is_traced_p() change:
- proc_is_traced_p() -> trace_is_enabled(), to match trace_enter() and
trace_exit().
- trace_is_enabled() becomes a real function.
- Remove unnecessary include files from various files that used to care
about KTRACE and SYSTRACE, but do no more.

syscall_fancy is only defined if either KTRACE or SYSTRACE is set,
so enclose its use in the same set of conditionals.

Always define syscall_fancy.

Add a proc_is_traced_p() macro and use it, instead of copying the same code
in many places. Idea from thorpej.

branches: 1.26.2;
implement PT_SYSCALL

branches: 1.25.4; 1.25.6;
merge ktrace-lwp.

branches: 1.24.2;
PR/29607: Christian Biere systrace doesn't handle interrupted syscalls properly
Instead of jumping to the default "bad" case, jump to the error handling
switch, so that we can deal with ERESTART/EJUSTRETURN properly.

Don't pass the (unused) return value args to the
trace_enter()/systrace_enter() functions.

Back out rev 1.19. It's wrong. Add comments so it doesn't happen again.

branches: 1.21.2;
Back out the lwp/ktrace changes. They contained a lot of colateral damage,
and need to be examined and discussed more.

Pass lwp pointers throughtout the kernel, as required, so that the lwpid can
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.

Bump the kernel rev up to 1.6V

Make sure to include opt_foo.h if a defflag option FOO is used.

Merge the nathanw_sa branch.

Pass the system call table to trace_enter() and ktrsys() so that it is
possible to use alternate system call tables. This is usefull for
displaying correctly the arguments in Mach binaries traces.

If NULL is given, then the regular systam call table for the process is used.

The recent mach trap support caused indirect system calls (a la syscall(2))
to be incorectly recorded as 'syscall'. Fix this.

Darwin skips the next instruction after a successful system call. Strange
world.

Add a realcode argument to trace_enter and ktrsyscall. realcode is the
original system call number, which can be negative for a Mach trap.
We cannot just replace code by realcode, because ktrsyscall uses it as
an index in the system call table, thus crashing the kernel when the
value is negative.

Change syscall to bound code so that systrace and ktrace won't fall off
the end of a table. XXX this is wrong since code does not indicate the
sysent table for which code was used as an index.

Get rid of nsysent. Use EMULNAMEU to use the appropriate constant.
Revamp the mach_syscall_dispatch function to be much simplier (pass in
a syscall code and return a const struct sysent * pointer).

Added support for Darwin's PowerPC-only system calls:
ppccalls, with system call numbers starting at 0x6000
fasttraps, with system call numbers starting at 0x7FF0

Because the Mach system call dispatching code has grown a bit
too much, introduce an inline function to handle it (mach_syscall_dispatch).

While we are there, remove the Mach and Linux includes from
arch/powerpc/powerpc/syscall.c and push them into
arch/powerpc/powerpc/{mach|linux}_syscall.c

back previous revision 1.9 off - compat code was changed to set
struct emul e_nsysent to *SYS_NSYSENT now, and the mask is more efficient

In struct emul, e_nsysent is *not* initialized to *SYS_NSYSENT but
*SYS_MAXSYSCALL. Adjust to this and simply compare 'code' to it instead
of doing the p-o-2 dance.

Move child_return back to syscall.c
Fix syscall to use emulations SYS_syscall/SYS___syscall definitions.
Use the emulation NSYSENT to limit code.
Don't define *syscall_fancy if it will never be used.

Fixed mistakes

Add COMPAT_MACH and EXEC_MACHO support on the PowerPC

Prepare syscall.c for COMPAT_MACH support. linux_syscall_intern is
moved to a Linux specific file, child_return is moved to trap.c,
and we introduce a EMULNAME macro co that syscall.c can be included to
define the system call handler for another emulation.

branches: 1.4.2;
use a completely separate trap handler for syscall traps.
this reduces syscall overhead by 10% to 20% depending on cpu type.

branches: 1.3.2;
create a syscall_plain() like on other platforms
and avoid getting the kernel lock for MPSAFE syscalls.

branches: 1.2.2;
Add a linux_syscall_intern entry (appropriately ifdef'ed COMPAT_LINUX).
When/if PPC ever supports LKMs, this should be moved to a separate file.

Add common syscall dispatcher. Also put child_return in here.