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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/um/Kconfig

@@ -62,63 +62,24 @@ 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"
 
 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"

arch/um/Kconfig.char

@@ -65,8 +65,6 @@ config XTERM_CHAN
         This option enables support for attaching UML consoles and serial
         lines to xterms.  Each UML device so assigned will be brought up in
         its own xterm.
-        If you disable this option, then CONFIG_PT_PROXY will be disabled as
-        well, since UML's gdb currently requires an xterm.
         It is safe to say 'Y' here.
 
 config NOCONFIG_CHAN

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.

arch/um/Makefile

@@ -31,18 +31,9 @@ SYMLINK_HEADERS := $(foreach header,$(SYMLINK_HEADERS),include/asm-um/$(header))
 ARCH_SYMLINKS = include/asm-um/arch $(ARCH_DIR)/include/sysdep $(ARCH_DIR)/os \
 	$(SYMLINK_HEADERS) $(ARCH_DIR)/include/uml-config.h
 
-um-modes-$(CONFIG_MODE_TT) += tt
-um-modes-$(CONFIG_MODE_SKAS) += skas
+MODE_INCLUDE	+= -I$(srctree)/$(ARCH_DIR)/include/skas
 
-MODE_INCLUDE	+= $(foreach mode,$(um-modes-y),\
-		   -I$(srctree)/$(ARCH_DIR)/include/$(mode))
-
-MAKEFILES-INCL	+= $(foreach mode,$(um-modes-y),\
-		   $(srctree)/$(ARCH_DIR)/Makefile-$(mode))
-
-ifneq ($(MAKEFILES-INCL),)
-  include $(MAKEFILES-INCL)
-endif
+include $(srctree)/$(ARCH_DIR)/Makefile-skas
 
 ARCH_INCLUDE	:= -I$(ARCH_DIR)/include
 ifneq ($(KBUILD_SRC),)
@@ -89,9 +80,8 @@ CFLAGS += $(call cc-option,-fno-unit-at-a-time,)
 # included; the values here are meaningless
 
 CONFIG_NEST_LEVEL ?= 0
-CONFIG_KERNEL_HALF_GIGS ?= 0
 
-SIZE = (($(CONFIG_NEST_LEVEL) + $(CONFIG_KERNEL_HALF_GIGS)) * 0x20000000)
+SIZE = ($(CONFIG_NEST_LEVEL) * 0x20000000)
 
 PHONY += linux
 
@@ -124,19 +114,15 @@ CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,)
 	$(call cc-option, -fno-stack-protector,) \
 	$(call cc-option, -fno-stack-protector-all,)
 
-CPP_MODE-$(CONFIG_MODE_TT) := -DMODE_TT
 CONFIG_KERNEL_STACK_ORDER ?= 2
 STACK_SIZE := $(shell echo $$[ 4096 * (1 << $(CONFIG_KERNEL_STACK_ORDER)) ] )
 
 ifndef START
   START = $(shell echo $$[ $(TOP_ADDR) - $(SIZE) ] )
 endif
 
-CPPFLAGS_vmlinux.lds = -U$(SUBARCH) \
-	-DSTART=$(START) -DELF_ARCH=$(ELF_ARCH) \
-	-DELF_FORMAT="$(ELF_FORMAT)" $(CPP_MODE-y) \
-	-DKERNEL_STACK_SIZE=$(STACK_SIZE) \
-	-DUNMAP_PATH=arch/um/sys-$(SUBARCH)/unmap.o
+CPPFLAGS_vmlinux.lds = -U$(SUBARCH) -DSTART=$(START) -DELF_ARCH=$(ELF_ARCH) \
+	-DELF_FORMAT="$(ELF_FORMAT)" -DKERNEL_STACK_SIZE=$(STACK_SIZE)
 
 #The wrappers will select whether using "malloc" or the kernel allocator.
 LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc

arch/um/Makefile-i386

@@ -2,11 +2,7 @@ core-y += arch/um/sys-i386/ arch/x86/crypto/
 
 TOP_ADDR := $(CONFIG_TOP_ADDR)
 
-ifeq ($(CONFIG_MODE_SKAS),y)
-  ifneq ($(CONFIG_MODE_TT),y)
-     START := 0x8048000
-  endif
-endif
+START := 0x8048000
 
 LDFLAGS			+= -m elf_i386
 ELF_ARCH		:= $(SUBARCH)

arch/um/defconfig

@@ -12,9 +12,7 @@ CONFIG_IRQ_RELEASE_METHOD=y
 #
 # UML-specific options
 #
-# CONFIG_MODE_TT is not set
 # CONFIG_STATIC_LINK is not set
-CONFIG_MODE_SKAS=y
 
 #
 # Host processor type and features

arch/um/drivers/mconsole_kern.c

@@ -735,8 +735,6 @@ void mconsole_sysrq(struct mc_request *req)
 }
 #endif
 
-#ifdef CONFIG_MODE_SKAS
-
 static void stack_proc(void *arg)
 {
 	struct task_struct *from = current, *to = arg;
@@ -750,7 +748,7 @@ static void stack_proc(void *arg)
  *  Dumps a stacks registers to the linux console.
  *  Usage stack <pid>.
  */
-static void do_stack_trace(struct mc_request *req)
+void mconsole_stack(struct mc_request *req)
 {
 	char *ptr = req->request.data;
 	int pid_requested= -1;
@@ -781,17 +779,6 @@ static void do_stack_trace(struct mc_request *req)
 	}
 	with_console(req, stack_proc, to);
 }
-#endif /* CONFIG_MODE_SKAS */
-
-void mconsole_stack(struct mc_request *req)
-{
-	/* This command doesn't work in TT mode, so let's check and then
-	 * get out of here
-	 */
-	CHOOSE_MODE(mconsole_reply(req, "Sorry, this doesn't work in TT mode",
-				   1, 0),
-		    do_stack_trace(req));
-}
 
 /* Changed by mconsole_setup, which is __setup, and called before SMP is
  * active.

arch/um/include/as-layout.h

@@ -28,7 +28,6 @@ extern unsigned long _unprotected_end;
 extern unsigned long brk_start;
 
 extern int linux_main(int argc, char **argv);
-extern void set_cmdline(char *cmd);
 
 extern void (*sig_info[])(int, union uml_pt_regs *);
 

arch/um/include/choose-mode.h

@@ -8,26 +8,8 @@
 
 #include "uml-config.h"
 
-#if defined(UML_CONFIG_MODE_TT) && defined(UML_CONFIG_MODE_SKAS)
-#define CHOOSE_MODE(tt, skas) (mode_tt ? (tt) : (skas))
-
-extern int mode_tt;
-static inline void *__choose_mode(void *tt, void *skas) {
-	return mode_tt ? tt : skas;
-}
-
-#define __CHOOSE_MODE(tt, skas) (*( (typeof(tt) *) __choose_mode(&(tt), &(skas))))
-
-#elif defined(UML_CONFIG_MODE_SKAS)
 #define CHOOSE_MODE(tt, skas) (skas)
 
-#elif defined(UML_CONFIG_MODE_TT)
-#define CHOOSE_MODE(tt, skas) (tt)
-
-#else
-#error CONFIG_MODE_SKAS and CONFIG_MODE_TT are both disabled
-#endif
-
 #define CHOOSE_MODE_PROC(tt, skas, args...) \
 	CHOOSE_MODE(tt(args), skas(args))
 

arch/um/include/common-offsets.h

@@ -1,9 +1,6 @@
 /* for use by sys-$SUBARCH/kernel-offsets.c */
 
 DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
-#ifdef CONFIG_MODE_TT
-OFFSET(HOST_TASK_EXTERN_PID, task_struct, thread.mode.tt.extern_pid);
-#endif
 
 OFFSET(HOST_TASK_REGS, task_struct, thread.regs);
 OFFSET(HOST_TASK_PID, task_struct, pid);

arch/um/include/irq_user.h

@@ -30,8 +30,4 @@ extern void deactivate_fd(int fd, int irqnum);
 extern int deactivate_all_fds(void);
 extern int activate_ipi(int fd, int pid);
 
-#ifdef CONFIG_MODE_TT
-extern void forward_interrupts(int pid);
-#endif
-
 #endif

arch/um/include/kern_util.h

@@ -34,9 +34,6 @@ extern int nsyscalls;
 	UML_ROUND_DOWN(((unsigned long) addr) + PAGE_SIZE - 1)
 
 extern int kernel_fork(unsigned long flags, int (*fn)(void *), void * arg);
-#ifdef UML_CONFIG_MODE_TT
-extern unsigned long stack_sp(unsigned long page);
-#endif
 extern int kernel_thread_proc(void *data);
 extern void syscall_segv(int sig);
 extern int current_pid(void);
@@ -82,9 +79,6 @@ extern void check_stack_overflow(void *ptr);
 extern void relay_signal(int sig, union uml_pt_regs *regs);
 extern int user_context(unsigned long sp);
 extern void timer_irq(union uml_pt_regs *regs);
-#ifdef CONFIG_MODE_TT
-extern void unprotect_stack(unsigned long stack);
-#endif
 extern void do_uml_exitcalls(void);
 extern int attach_debugger(int idle_pid, int pid, int stop);
 extern int config_gdb(char *str);

arch/um/include/mode.h

@@ -6,25 +6,6 @@
 #ifndef __MODE_H__
 #define __MODE_H__
 
-#include "uml-config.h"
-
-#ifdef UML_CONFIG_MODE_TT
-#include "mode-tt.h"
-#endif
-
-#ifdef UML_CONFIG_MODE_SKAS
 #include "mode-skas.h"
-#endif
 
 #endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */

arch/um/include/mode_kern.h

@@ -6,12 +6,6 @@
 #ifndef __MODE_KERN_H__
 #define __MODE_KERN_H__
 
-#ifdef CONFIG_MODE_TT
-#include "mode_kern_tt.h"
-#endif
-
-#ifdef CONFIG_MODE_SKAS
 #include "mode_kern_skas.h"
-#endif
 
 #endif