uml: throw out CONFIG_MODE_TT

This patchset throws out tt mode, which has been non-functional for a while.

This is done in phases, interspersed with code cleanups on the affected files.

The removal is done as follows:
	remove all code, config options, and files which depend on
CONFIG_MODE_TT
	get rid of the CHOOSE_MODE macro, which decided whether to
call tt-mode or skas-mode code, and replace invocations with their
skas portions
	replace all now-trivial procedures with their skas equivalents

There are now a bunch of now-redundant pieces of data structures, including
mode-specific pieces of the thread structure, pt_regs, and mm_context.  These
are all replaced with their skas-specific contents.

As part of the ongoing style compliance project, I made a style pass over all
files that were changed.  There are three such patches, one for each phase,
covering the files affected by that phase but no later ones.

I noticed that we weren't freeing the LDT state associated with a process when
it exited, so that's fixed in one of the later patches.

The last patch is a tidying patch which I've had for a while, but which caused
inexplicable crashes under tt mode.  Since that is no longer a problem, this
can now go in.

This patch:

Start getting rid of tt mode support.

This patch throws out CONFIG_MODE_TT and all config options, code, and files
which depend on it.

CONFIG_MODE_SKAS is gone and everything that depends on it is included
unconditionally.

The few changed lines are in re-written Kconfig help, lines which needed
something skas-related removed from them, and a few more which weren't
strictly deletions.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/Kconfig.debug

@@ -2,28 +2,9 @@ menu "Kernel hacking"
 
 source "lib/Kconfig.debug"
 
-config CMDLINE_ON_HOST
-	bool "Show command line arguments on the host in TT mode"
-	depends on MODE_TT
-	default !DEBUG_INFO
-	help
-	This controls whether arguments in guest processes should be shown on
-	the host's ps output.
-	Enabling this option hinders debugging on some recent GDB versions
-	(because GDB gets "confused" when we do an execvp()). So probably you
-	should disable it.
-
-config PT_PROXY
-	bool "Enable ptrace proxy"
-	depends on XTERM_CHAN && DEBUG_INFO && MODE_TT
-	help
-	This option enables a debugging interface which allows gdb to debug
-	the kernel without needing to actually attach to kernel threads.
-	If you want to do kernel debugging, say Y here; otherwise say N.
-
 config GPROF
 	bool "Enable gprof support"
-	depends on DEBUG_INFO && MODE_SKAS && !MODE_TT
+	depends on DEBUG_INFO
 	help
         This allows profiling of a User-Mode Linux kernel with the gprof
         utility.
@@ -36,7 +17,7 @@ config GPROF
 
 config GCOV
 	bool "Enable gcov support"
-	depends on DEBUG_INFO && MODE_SKAS
+	depends on DEBUG_INFO
 	help
         This option allows developers to retrieve coverage data from a UML
         session.