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, 10 insertions, 54 deletions

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index e6ff30266542..a0e47e271156 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -62,55 +62,16 @@ config IRQ_RELEASE_METHOD
 
 menu "UML-specific options"
 
-config MODE_TT
-        bool "Tracing thread support (DEPRECATED)"
-        default n
-        depends on BROKEN
-        help
-        This option controls whether tracing thread support is compiled
-        into UML. This option is largely obsolete, given that skas0 provides
-        skas security and performance without needing to patch the host.
-        It is safe to say 'N' here; saying 'Y' may cause additional problems
-        with the resulting binary even if you run UML in SKAS mode, and running
-        in TT mode is strongly *NOT RECOMMENDED*.
-
 config STATIC_LINK
         bool "Force a static link"
         default n
-        depends on !MODE_TT
         help
-        If CONFIG_MODE_TT is disabled, then this option gives you the ability
-        to force a static link of UML.  Normally, if only skas mode is built
-        in to UML, it will be linked as a shared binary.  This is inconvenient
-        for use in a chroot jail.  So, if you intend to run UML inside a
-        chroot, and you disable CONFIG_MODE_TT, you probably want to say Y
-        here.
+        This option gives you the ability to force a static link of UML.
+        Normally, UML is linked as a shared binary.  This is inconvenient for
+        use in a chroot jail.  So, if you intend to run UML inside a chroot,
+        you probably want to say Y here.
         Additionally, this option enables using higher memory spaces (up to
-        2.75G) for UML - disabling CONFIG_MODE_TT and enabling this option leads
-        to best results for this.
-
-config KERNEL_HALF_GIGS
-        int "Kernel address space size (in .5G units)"
-        default "1"
-        depends on MODE_TT
-        help
-        This determines the amount of address space that UML will allocate for
-        its own, measured in half Gigabyte units.  The default is 1.
-        Change this only if you need to boot UML with an unusually large amount
-        of physical memory.
-
-config MODE_SKAS
-        bool "Separate Kernel Address Space support" if MODE_TT
-        default y
-        help
-        This option controls whether skas (separate kernel address space)
-        support is compiled in.
-        Unless you have specific needs to use TT mode (which applies almost only
-        to developers), you should say Y here.
-        SKAS mode will make use of the SKAS3 patch if it is applied on the host
-        (and your UML will run in SKAS3 mode), but if no SKAS patch is applied
-        on the host it will run in SKAS0 mode, which is anyway faster than TT
-        mode.
+        2.75G) for UML.
 
 source "arch/um/Kconfig.arch"
 source "mm/Kconfig"
@@ -118,7 +79,7 @@ source "mm/Kconfig"
 config LD_SCRIPT_STATIC
         bool
         default y
-        depends on MODE_TT || STATIC_LINK
+        depends on STATIC_LINK
 
 config LD_SCRIPT_DYN
         bool
@@ -220,7 +181,7 @@ config SMP
         bool "Symmetric multi-processing support (EXPERIMENTAL)"
         default n
         #SMP_BROKEN is for x86_64.
-        depends on MODE_TT && EXPERIMENTAL && (!SMP_BROKEN || (BROKEN && SMP_BROKEN))
+        depends on EXPERIMENTAL && (!SMP_BROKEN || (BROKEN && SMP_BROKEN))
         help
         This option enables UML SMP support.
         It is NOT related to having a real SMP box. Not directly, at least.
@@ -258,11 +219,6 @@ config NEST_LEVEL
         inside another UML, set CONFIG_NEST_LEVEL to one more than the host
         UML.
 
-        Note that if the hosting UML has its CONFIG_KERNEL_HALF_GIGS set to
-        greater than one, then the guest UML should have its CONFIG_NEST_LEVEL
-        set to the host's CONFIG_NEST_LEVEL + CONFIG_KERNEL_HALF_GIGS.
-        Only change this if you are running nested UMLs.
-
 config HIGHMEM
         bool "Highmem support (EXPERIMENTAL)"
         depends on !64BIT && EXPERIMENTAL
@@ -271,9 +227,9 @@ config HIGHMEM
         This was used to allow UML to run with big amounts of memory.
         Currently it is unstable, so if unsure say N.
 
-        To use big amounts of memory, it is recommended to disable TT mode (i.e.
-        CONFIG_MODE_TT) and enable static linking (i.e. CONFIG_STATIC_LINK) -
-        this should allow the guest to use up to 2.75G of memory.
+        To use big amounts of memory, it is recommended enable static
+        linking (i.e. CONFIG_STATIC_LINK) - this should allow the
+        guest to use up to 2.75G of memory.
 
 config KERNEL_STACK_ORDER
         int "Kernel stack size order"