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>

1 files changed, 4 insertions, 109 deletions

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index ecc458fe51b9..aa7b067565d9 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -38,9 +38,7 @@
 #include "choose-mode.h"
 #include "mode_kern.h"
 #include "mode.h"
-#ifdef UML_CONFIG_MODE_SKAS
 #include "skas.h"
-#endif
 
 #define DEFAULT_COMMAND_LINE "root=98:0"
 
@@ -132,43 +130,12 @@ unsigned long end_vm;
 /* Set in uml_ncpus_setup */
 int ncpus = 1;
 
-#ifdef CONFIG_CMDLINE_ON_HOST
-/* Pointer set in linux_main, the array itself is private to each thread,
- * and changed at address space creation time so this poses no concurrency
- * problems.
- */
-static char *argv1_begin = NULL;
-static char *argv1_end = NULL;
-#endif
-
 /* Set in early boot */
 static int have_root __initdata = 0;
 
 /* Set in uml_mem_setup and modified in linux_main */
 long long physmem_size = 32 * 1024 * 1024;
 
-void set_cmdline(char *cmd)
-{
-#ifdef CONFIG_CMDLINE_ON_HOST
-        char *umid, *ptr;
-
-        if(CHOOSE_MODE(honeypot, 0)) return;
-
-        umid = get_umid();
-        if(*umid != '\0'){
-                snprintf(argv1_begin, 
-                         (argv1_end - argv1_begin) * sizeof(*ptr), 
-                         "(%s) ", umid);
-                ptr = &argv1_begin[strlen(argv1_begin)];
-        }
-        else ptr = argv1_begin;
-
-        snprintf(ptr, (argv1_end - ptr) * sizeof(*ptr), "[%s]", cmd);
-        memset(argv1_begin + strlen(argv1_begin), '\0', 
-               argv1_end - argv1_begin - strlen(argv1_begin));
-#endif
-}
-
 static char *usage_string = 
 "User Mode Linux v%s\n"
 "       available at http://user-mode-linux.sourceforge.net/\n\n";
@@ -201,13 +168,10 @@ __uml_setup("root=", uml_root_setup,
 "        root=/dev/ubd5\n\n"
 );
 
-#ifndef CONFIG_MODE_TT
-
 static int __init no_skas_debug_setup(char *line, int *add)
 {
         printf("'debug' is not necessary to gdb UML in skas mode - run \n");
-        printf("'gdb linux' and disable CONFIG_CMDLINE_ON_HOST if gdb \n");
-        printf("doesn't work as expected\n");
+        printf("'gdb linux'");
 
         return 0;
 }
@@ -217,8 +181,6 @@ __uml_setup("debug", no_skas_debug_setup,
 "    this flag is not needed to run gdb on UML in skas mode\n\n"
 );
 
-#endif
-
 #ifdef CONFIG_SMP
 static int __init uml_ncpus_setup(char *line, int *add)
 {
@@ -236,52 +198,6 @@ __uml_setup("ncpus=", uml_ncpus_setup,
 );
 #endif
 
-static int force_tt = 0;
-
-#if defined(CONFIG_MODE_TT) && defined(CONFIG_MODE_SKAS)
-#define DEFAULT_TT 0
-
-static int __init mode_tt_setup(char *line, int *add)
-{
-        force_tt = 1;
-        return 0;
-}
-
-#else
-#ifdef CONFIG_MODE_SKAS
-
-#define DEFAULT_TT 0
-
-static int __init mode_tt_setup(char *line, int *add)
-{
-        printf("CONFIG_MODE_TT disabled - 'mode=tt' ignored\n");
-        return 0;
-}
-
-#else
-#ifdef CONFIG_MODE_TT
-
-#define DEFAULT_TT 1
-
-static int __init mode_tt_setup(char *line, int *add)
-{
-        printf("CONFIG_MODE_SKAS disabled - 'mode=tt' redundant\n");
-        return 0;
-}
-
-#endif
-#endif
-#endif
-
-__uml_setup("mode=tt", mode_tt_setup,
-"mode=tt\n"
-"    When both CONFIG_MODE_TT and CONFIG_MODE_SKAS are enabled, this option\n"
-"    forces UML to run in tt (tracing thread) mode.  It is not the default\n"
-"    because it's slower and less secure than skas mode.\n\n"
-);
-
-int mode_tt = DEFAULT_TT;
-
 static int __init Usage(char *line, int *add)
 {
         const char **p;
@@ -357,29 +273,13 @@ int __init linux_main(int argc, char **argv)
                 add_arg(DEFAULT_COMMAND_LINE);
 
         os_early_checks();
-        if (force_tt)
-                clear_can_do_skas();
-        mode_tt = force_tt ? 1 : !can_do_skas();
-#ifndef CONFIG_MODE_TT
-        if (mode_tt) {
-                /*Since CONFIG_MODE_TT is #undef'ed, force_tt cannot be 1. So,
-                 * can_do_skas() returned 0, and the message is correct. */
-                printf("Support for TT mode is disabled, and no SKAS support is present on the host.\n");
-                exit(1);
-        }
-#endif
 
-#ifndef CONFIG_MODE_SKAS
-        mode = "TT";
-#else
-        /* Show to the user the result of selection */
-        if (mode_tt)
-                mode = "TT";
-        else if (proc_mm && ptrace_faultinfo)
+        can_do_skas();
+
+        if (proc_mm && ptrace_faultinfo)
                 mode = "SKAS3";
         else
                 mode = "SKAS0";
-#endif
 
         printf("UML running in %s mode\n", mode);
 
@@ -411,11 +311,6 @@ int __init linux_main(int argc, char **argv)
 
         setup_machinename(init_utsname()->machine);
 
-#ifdef CONFIG_CMDLINE_ON_HOST
-        argv1_begin = argv[1];
-        argv1_end = &argv[1][strlen(argv[1])];
-#endif
-
         highmem = 0;
         iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
         max_physmem = get_kmem_end() - uml_physmem - iomem_size - MIN_VMALLOC;