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/include/os.h

@@ -178,11 +178,7 @@ extern void check_host_supports_tls(int *supports_tls, int *tls_min);
 
 /* Make sure they are clear when running in TT mode. Required by
  * SEGV_MAYBE_FIXABLE */
-#ifdef UML_CONFIG_MODE_SKAS
 #define clear_can_do_skas() do { ptrace_faultinfo = proc_mm = 0; } while (0)
-#else
-#define clear_can_do_skas() do {} while (0)
-#endif
 
 /* mem.c */
 extern int create_mem_file(unsigned long long len);
@@ -193,18 +189,11 @@ extern int os_process_parent(int pid);
 extern void os_stop_process(int pid);
 extern void os_kill_process(int pid, int reap_child);
 extern void os_kill_ptraced_process(int pid, int reap_child);
-#ifdef UML_CONFIG_MODE_TT
-extern void os_usr1_process(int pid);
-#endif
 extern long os_ptrace_ldt(long pid, long addr, long data);
 
 extern int os_getpid(void);
 extern int os_getpgrp(void);
 
-#ifdef UML_CONFIG_MODE_TT
-extern void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int));
-extern void stop(void);
-#endif
 extern void init_new_thread_signals(void);
 extern int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr);
 
@@ -217,18 +206,6 @@ extern int os_drop_memory(void *addr, int length);
 extern int can_drop_memory(void);
 extern void os_flush_stdout(void);
 
-/* tt.c
- * for tt mode only (will be deleted in future...)
- */
-extern void forward_ipi(int fd, int pid);
-extern void kill_child_dead(int pid);
-extern int wait_for_stop(int pid, int sig, int cont_type, void *relay);
-extern int protect_memory(unsigned long addr, unsigned long len,
-			  int r, int w, int x, int must_succeed);
-extern void forward_pending_sigio(int target);
-extern int start_fork_tramp(void *arg, unsigned long temp_stack,
-			    int clone_flags, int (*tramp)(void *));
-
 /* uaccess.c */
 extern unsigned long __do_user_copy(void *to, const void *from, int n,
 				    void **fault_addr, void **fault_catcher,
@@ -281,9 +258,6 @@ extern void os_dump_core(void);
 extern void switch_timers(int to_real);
 extern void idle_sleep(int secs);
 extern int set_interval(int is_virtual);
-#ifdef CONFIG_MODE_TT
-extern void enable_timer(void);
-#endif
 extern void disable_timer(void);
 extern void uml_idle_timer(void);
 extern unsigned long long os_nsecs(void);