kernel_optimize_test/arch/um/include/sysdep-i386
Paolo 'Blaisorblade' Giarrusso 972410b023 [PATCH] uml: clean arch_switch usage
Call arch_switch also in switch_to_skas, even if it's, for now, a no-op for
that case (and mark this in the comment); this will change soon.

Also, arch_switch for TT mode is actually useless when the PT proxy (a
complicate debugging instrumentation for TT mode) is not enabled.  In fact, it
only calls update_debugregs, which checks debugregs_seq against seq (to check
if the registers are up-to-date - seq here means a "version number" of the
registers).

If the ptrace proxy is not enabled, debugregs_seq always stays 0 and
update_debugregs will be a no-op.  So, optimize this out (the compiler can't
do it).

Also, I've been disappointed by the fact that it would make a lot of sense if,
after calling a successful
update_debugregs(current->thread.arch.debugregs_seq),
current->thread.arch.debugregs_seq were updated with the new debugregs_seq.
But this is not done.  Is this a bug or a feature?  For all purposes, it seems
a bug (otherwise the whole mechanism does not make sense, which is also a
possibility to check), which causes some performance only problems (not
correctness), since we write_debugregs when not needed.

Also, as suggested by Jeff, remove a redundant enabling of SIGVTALRM,
comprised in the subsequent local_irq_enable().  I'm just a bit dubious if
ordering matters there...

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-31 12:18:52 -08:00
..
checksum.h [PATCH] uml: sparse cleanups 2006-03-31 12:18:51 -08:00
faultinfo.h [PATCH] uml: S390 preparation, abstract host page fault data 2005-05-05 16:36:36 -07:00
kernel-offsets.h [PATCH] uml: fix missing KBUILD_BASENAME 2006-01-11 18:42:09 -08:00
ptrace_user.h [PATCH] uml: skas0 - separate kernel address space on stock hosts 2005-07-07 18:23:44 -07:00
ptrace.h [PATCH] uml: clean arch_switch usage 2006-03-31 12:18:52 -08:00
sc.h [PATCH] uml makefiles sanitized 2005-09-29 08:46:26 -07:00
sigcontext.h [PATCH] uml: fix page faults in SKAS3 mode. 2005-09-30 12:41:18 -07:00
signal.h [PATCH] uml: s390 preparation, sighandler interface abstraction 2005-05-05 16:36:38 -07:00
skas_ptrace.h [PATCH] uml: S390 preparation, abstract host page fault data 2005-05-05 16:36:36 -07:00
stub.h [PATCH] uml skas0: stop gcc's insanity 2005-12-18 11:19:44 -08:00
syscalls.h [PATCH] unify sys_ptrace prototype 2005-10-30 17:37:20 -08:00
thread.h [PATCH] uml: fix compile failure for TT mode 2005-10-24 08:59:25 -07:00