diff mbox series

[10/14] uaccess: remove most CONFIG_SET_FS users

Message ID 20220214163452.1568807-11-arnd@kernel.org (mailing list archive)
State New, archived
Headers show
Series clean up asm/uaccess.h, kill set_fs for good | expand

Commit Message

Arnd Bergmann Feb. 14, 2022, 4:34 p.m. UTC
From: Arnd Bergmann <arnd@arndb.de>

On almost all architectures, there are no remaining callers
of set_fs(), so CONFIG_SET_FS can be disabled, along with
removing the thread_info field and any references to it.

This turns access_ok() into a cheaper check against TASK_SIZE_MAX.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/alpha/Kconfig                        |  1 -
 arch/alpha/include/asm/processor.h        |  4 --
 arch/alpha/include/asm/thread_info.h      |  2 -
 arch/alpha/include/asm/uaccess.h          | 19 ------
 arch/arc/Kconfig                          |  1 -
 arch/arc/include/asm/segment.h            | 20 -------
 arch/arc/include/asm/thread_info.h        |  3 -
 arch/arc/include/asm/uaccess.h            |  1 -
 arch/csky/Kconfig                         |  1 -
 arch/csky/include/asm/processor.h         |  2 -
 arch/csky/include/asm/segment.h           | 10 ----
 arch/csky/include/asm/thread_info.h       |  2 -
 arch/csky/include/asm/uaccess.h           |  3 -
 arch/csky/kernel/asm-offsets.c            |  1 -
 arch/h8300/Kconfig                        |  1 -
 arch/h8300/include/asm/processor.h        |  1 -
 arch/h8300/include/asm/segment.h          | 40 -------------
 arch/h8300/include/asm/thread_info.h      |  3 -
 arch/h8300/kernel/entry.S                 |  1 -
 arch/h8300/kernel/head_ram.S              |  1 -
 arch/h8300/mm/init.c                      |  6 --
 arch/h8300/mm/memory.c                    |  1 -
 arch/hexagon/Kconfig                      |  1 -
 arch/hexagon/include/asm/thread_info.h    |  6 --
 arch/hexagon/kernel/process.c             |  1 -
 arch/microblaze/Kconfig                   |  1 -
 arch/microblaze/include/asm/thread_info.h |  6 --
 arch/microblaze/include/asm/uaccess.h     | 24 --------
 arch/microblaze/kernel/asm-offsets.c      |  1 -
 arch/microblaze/kernel/process.c          |  1 -
 arch/nds32/Kconfig                        |  1 -
 arch/nds32/include/asm/thread_info.h      |  4 --
 arch/nds32/include/asm/uaccess.h          | 15 +----
 arch/nds32/mm/alignment.c                 |  3 -
 arch/nios2/Kconfig                        |  1 -
 arch/nios2/include/asm/thread_info.h      |  9 ---
 arch/nios2/include/asm/uaccess.h          | 12 ----
 arch/openrisc/Kconfig                     |  1 -
 arch/openrisc/include/asm/thread_info.h   |  7 ---
 arch/openrisc/include/asm/uaccess.h       | 23 --------
 arch/sparc/Kconfig                        |  2 +-
 arch/sparc/include/asm/processor_32.h     |  6 --
 arch/sparc/include/asm/uaccess_32.h       | 13 -----
 arch/sparc/kernel/process_32.c            |  2 -
 arch/xtensa/Kconfig                       |  1 -
 arch/xtensa/include/asm/asm-uaccess.h     | 71 -----------------------
 arch/xtensa/include/asm/processor.h       |  7 ---
 arch/xtensa/include/asm/thread_info.h     |  3 -
 arch/xtensa/include/asm/uaccess.h         | 16 -----
 arch/xtensa/kernel/asm-offsets.c          |  3 -
 include/asm-generic/uaccess.h             | 25 +-------
 51 files changed, 3 insertions(+), 387 deletions(-)
 delete mode 100644 arch/arc/include/asm/segment.h
 delete mode 100644 arch/csky/include/asm/segment.h
 delete mode 100644 arch/h8300/include/asm/segment.h

Comments

Christoph Hellwig Feb. 14, 2022, 5:06 p.m. UTC | #1
On Mon, Feb 14, 2022 at 05:34:48PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> On almost all architectures, there are no remaining callers
> of set_fs(), so CONFIG_SET_FS can be disabled, along with
> removing the thread_info field and any references to it.
> 
> This turns access_ok() into a cheaper check against TASK_SIZE_MAX.

Wouldn't it make more sense to just merge this into the last patch?
Arnd Bergmann Feb. 14, 2022, 7:40 p.m. UTC | #2
On Mon, Feb 14, 2022 at 6:06 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Feb 14, 2022 at 05:34:48PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > On almost all architectures, there are no remaining callers
> > of set_fs(), so CONFIG_SET_FS can be disabled, along with
> > removing the thread_info field and any references to it.
> >
> > This turns access_ok() into a cheaper check against TASK_SIZE_MAX.
>
> Wouldn't it make more sense to just merge this into the last patch?

Yes, sounds good. I wasn't sure at first if there is enough buy-in to get
all architectures cleaned up, and I hadn't done the ia64 patch, so it
seemed more important to do this part early, but now it seems that it
will all go in at the same time, so doing this as part of a big removal
at the end makes sense.

        Arnd
diff mbox series

Patch

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 4e87783c90ad..eee8b5b0a58b 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -35,7 +35,6 @@  config ALPHA
 	select OLD_SIGSUSPEND
 	select CPU_NO_EFFICIENT_FFS if !ALPHA_EV67
 	select MMU_GATHER_NO_RANGE
-	select SET_FS
 	select SPARSEMEM_EXTREME if SPARSEMEM
 	select ZONE_DMA
 	help
diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
index 090499c99c1c..43e234c518b1 100644
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -26,10 +26,6 @@ 
 #define TASK_UNMAPPED_BASE \
   ((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2)
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 /* This is dead.  Everything has been moved to thread_info.  */
 struct thread_struct { };
 #define INIT_THREAD  { }
diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 2592356e3215..fdc485d7787a 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -19,7 +19,6 @@  struct thread_info {
 	unsigned int		flags;		/* low level flags */
 	unsigned int		ieee_state;	/* see fpu.h */
 
-	mm_segment_t		addr_limit;	/* thread address space */
 	unsigned		cpu;		/* current CPU */
 	int			preempt_count; /* 0 => preemptable, <0 => BUG */
 	unsigned int		status;		/* thread-synchronous flags */
@@ -35,7 +34,6 @@  struct thread_info {
 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.task		= &tsk,			\
-	.addr_limit	= KERNEL_DS,		\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\
 }
 
diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 82c5743fc9cd..c32c2584c0b7 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -2,26 +2,7 @@ 
 #ifndef __ALPHA_UACCESS_H
 #define __ALPHA_UACCESS_H
 
-/*
- * The fs value determines whether argument validity checking should be
- * performed or not.  If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * Or at least it did once upon a time.  Nowadays it is a mask that
- * defines which bits of the address space are off limits.  This is a
- * wee bit faster than the above.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
-
-#define KERNEL_DS	((mm_segment_t) { 0UL })
-#define USER_DS		((mm_segment_t) { -0x40000000000UL })
-
-#define get_fs()  (current_thread_info()->addr_limit)
-#define set_fs(x) (current_thread_info()->addr_limit = (x))
-
 #include <asm-generic/access_ok.h>
-
 /*
  * These are the main single-value transfer routines.  They automatically
  * use the right size if we just have the right pointer type.
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 3c2a4753d09b..e0a60a27e14d 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -45,7 +45,6 @@  config ARC
 	select PCI_SYSCALL if PCI
 	select PERF_USE_VMALLOC if ARC_CACHE_VIPT_ALIASING
 	select HAVE_ARCH_JUMP_LABEL if ISA_ARCV2 && !CPU_ENDIAN_BE32
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 
 config LOCKDEP_SUPPORT
diff --git a/arch/arc/include/asm/segment.h b/arch/arc/include/asm/segment.h
deleted file mode 100644
index 871f8ab11bfd..000000000000
--- a/arch/arc/include/asm/segment.h
+++ /dev/null
@@ -1,20 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
- */
-
-#ifndef __ASMARC_SEGMENT_H
-#define __ASMARC_SEGMENT_H
-
-#ifndef __ASSEMBLY__
-
-typedef unsigned long mm_segment_t;
-
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-
-#define KERNEL_DS		MAKE_MM_SEG(0)
-#define USER_DS			MAKE_MM_SEG(TASK_SIZE)
-#define uaccess_kernel()	(get_fs() == KERNEL_DS)
-
-#endif /* __ASSEMBLY__ */
-#endif /* __ASMARC_SEGMENT_H */
diff --git a/arch/arc/include/asm/thread_info.h b/arch/arc/include/asm/thread_info.h
index d36863e34bfc..1e0b2e3914d5 100644
--- a/arch/arc/include/asm/thread_info.h
+++ b/arch/arc/include/asm/thread_info.h
@@ -27,7 +27,6 @@ 
 #ifndef __ASSEMBLY__
 
 #include <linux/thread_info.h>
-#include <asm/segment.h>
 
 /*
  * low level task data that entry.S needs immediate access to
@@ -40,7 +39,6 @@  struct thread_info {
 	unsigned long flags;		/* low level flags */
 	int preempt_count;		/* 0 => preemptable, <0 => BUG */
 	struct task_struct *task;	/* main task structure */
-	mm_segment_t addr_limit;	/* thread address space */
 	__u32 cpu;			/* current CPU */
 	unsigned long thr_ptr;		/* TLS ptr */
 };
@@ -56,7 +54,6 @@  struct thread_info {
 	.flags      = 0,			\
 	.cpu        = 0,			\
 	.preempt_count  = INIT_PREEMPT_COUNT,	\
-	.addr_limit = KERNEL_DS,		\
 }
 
 static inline __attribute_const__ struct thread_info *current_thread_info(void)
diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h
index 30f80b4be2ab..99712471c96a 100644
--- a/arch/arc/include/asm/uaccess.h
+++ b/arch/arc/include/asm/uaccess.h
@@ -638,7 +638,6 @@  extern unsigned long arc_clear_user_noinline(void __user *to,
 #define __clear_user(d, n)		arc_clear_user_noinline(d, n)
 #endif
 
-#include <asm/segment.h>
 #include <asm-generic/uaccess.h>
 
 #endif
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 132f43f12dd8..75ef86605d69 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -79,7 +79,6 @@  config CSKY
 	select PCI_DOMAINS_GENERIC if PCI
 	select PCI_SYSCALL if PCI
 	select PCI_MSI if PCI
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 
 config LOCKDEP_SUPPORT
diff --git a/arch/csky/include/asm/processor.h b/arch/csky/include/asm/processor.h
index 817dd60ff152..688c7548b559 100644
--- a/arch/csky/include/asm/processor.h
+++ b/arch/csky/include/asm/processor.h
@@ -4,7 +4,6 @@ 
 #define __ASM_CSKY_PROCESSOR_H
 
 #include <linux/bitops.h>
-#include <asm/segment.h>
 #include <asm/ptrace.h>
 #include <asm/current.h>
 #include <asm/cache.h>
@@ -59,7 +58,6 @@  struct thread_struct {
  */
 #define start_thread(_regs, _pc, _usp)					\
 do {									\
-	set_fs(USER_DS); /* reads from user space */			\
 	(_regs)->pc = (_pc);						\
 	(_regs)->regs[1] = 0; /* ABIV1 is R7, uClibc_main rtdl arg */	\
 	(_regs)->regs[2] = 0;						\
diff --git a/arch/csky/include/asm/segment.h b/arch/csky/include/asm/segment.h
deleted file mode 100644
index 5bc1cc62b87f..000000000000
--- a/arch/csky/include/asm/segment.h
+++ /dev/null
@@ -1,10 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0 */
-
-#ifndef __ASM_CSKY_SEGMENT_H
-#define __ASM_CSKY_SEGMENT_H
-
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
-#endif /* __ASM_CSKY_SEGMENT_H */
diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h
index 8c349a8f904d..b5ed788f0c68 100644
--- a/arch/csky/include/asm/thread_info.h
+++ b/arch/csky/include/asm/thread_info.h
@@ -16,7 +16,6 @@  struct thread_info {
 	unsigned long		flags;
 	int			preempt_count;
 	unsigned long		tp_value;
-	mm_segment_t		addr_limit;
 	struct restart_block	restart_block;
 	struct pt_regs		*regs;
 	unsigned int		cpu;
@@ -26,7 +25,6 @@  struct thread_info {
 {						\
 	.task		= &tsk,			\
 	.preempt_count  = INIT_PREEMPT_COUNT,	\
-	.addr_limit     = KERNEL_DS,		\
 	.cpu		= 0,			\
 	.restart_block = {			\
 		.fn = do_no_restart_syscall,	\
diff --git a/arch/csky/include/asm/uaccess.h b/arch/csky/include/asm/uaccess.h
index fec8f77ffc99..2e927c21d8a1 100644
--- a/arch/csky/include/asm/uaccess.h
+++ b/arch/csky/include/asm/uaccess.h
@@ -3,8 +3,6 @@ 
 #ifndef __ASM_CSKY_UACCESS_H
 #define __ASM_CSKY_UACCESS_H
 
-#define user_addr_max() (current_thread_info()->addr_limit.seg)
-
 /*
  * __put_user_fn
  */
@@ -200,7 +198,6 @@  unsigned long raw_copy_to_user(void *to, const void *from, unsigned long n);
 unsigned long __clear_user(void __user *to, unsigned long n);
 #define __clear_user __clear_user
 
-#include <asm/segment.h>
 #include <asm-generic/uaccess.h>
 
 #endif /* __ASM_CSKY_UACCESS_H */
diff --git a/arch/csky/kernel/asm-offsets.c b/arch/csky/kernel/asm-offsets.c
index 1cbcba4b0dd1..d1e903579473 100644
--- a/arch/csky/kernel/asm-offsets.c
+++ b/arch/csky/kernel/asm-offsets.c
@@ -25,7 +25,6 @@  int main(void)
 	/* offsets into the thread_info struct */
 	DEFINE(TINFO_FLAGS,       offsetof(struct thread_info, flags));
 	DEFINE(TINFO_PREEMPT,     offsetof(struct thread_info, preempt_count));
-	DEFINE(TINFO_ADDR_LIMIT,  offsetof(struct thread_info, addr_limit));
 	DEFINE(TINFO_TP_VALUE,   offsetof(struct thread_info, tp_value));
 	DEFINE(TINFO_TASK,        offsetof(struct thread_info, task));
 
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index 3e3e0f16f7e0..fe48c4f26cc8 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -24,7 +24,6 @@  config H8300
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_HASH
 	select CPU_NO_EFFICIENT_FFS
-	select SET_FS
 	select UACCESS_MEMCPY
 
 config CPU_BIG_ENDIAN
diff --git a/arch/h8300/include/asm/processor.h b/arch/h8300/include/asm/processor.h
index 141a23eb62b7..ba171aa4dacb 100644
--- a/arch/h8300/include/asm/processor.h
+++ b/arch/h8300/include/asm/processor.h
@@ -13,7 +13,6 @@ 
 #define __ASM_H8300_PROCESSOR_H
 
 #include <linux/compiler.h>
-#include <asm/segment.h>
 #include <asm/ptrace.h>
 #include <asm/current.h>
 
diff --git a/arch/h8300/include/asm/segment.h b/arch/h8300/include/asm/segment.h
deleted file mode 100644
index 37950725d9b9..000000000000
--- a/arch/h8300/include/asm/segment.h
+++ /dev/null
@@ -1,40 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _H8300_SEGMENT_H
-#define _H8300_SEGMENT_H
-
-/* define constants */
-#define USER_DATA     (1)
-#ifndef __USER_DS
-#define __USER_DS     (USER_DATA)
-#endif
-#define USER_PROGRAM  (2)
-#define SUPER_DATA    (3)
-#ifndef __KERNEL_DS
-#define __KERNEL_DS   (SUPER_DATA)
-#endif
-#define SUPER_PROGRAM (4)
-
-#ifndef __ASSEMBLY__
-
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-#define USER_DS		MAKE_MM_SEG(__USER_DS)
-#define KERNEL_DS	MAKE_MM_SEG(__KERNEL_DS)
-
-/*
- * Get/set the SFC/DFC registers for MOVES instructions
- */
-
-static inline mm_segment_t get_fs(void)
-{
-	return USER_DS;
-}
-
-#define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
-
-#endif /* __ASSEMBLY__ */
-
-#endif /* _H8300_SEGMENT_H */
diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h
index a518214d4ddd..ff2d873749a4 100644
--- a/arch/h8300/include/asm/thread_info.h
+++ b/arch/h8300/include/asm/thread_info.h
@@ -10,7 +10,6 @@ 
 #define _ASM_THREAD_INFO_H
 
 #include <asm/page.h>
-#include <asm/segment.h>
 
 #ifdef __KERNEL__
 
@@ -31,7 +30,6 @@  struct thread_info {
 	unsigned long	   flags;		/* low level flags */
 	int		   cpu;			/* cpu we're on */
 	int		   preempt_count;	/* 0 => preemptable, <0 => BUG */
-	mm_segment_t		addr_limit;
 };
 
 /*
@@ -43,7 +41,6 @@  struct thread_info {
 	.flags =	0,			\
 	.cpu =		0,			\
 	.preempt_count = INIT_PREEMPT_COUNT,	\
-	.addr_limit	= KERNEL_DS,		\
 }
 
 /* how to get the thread information struct from C */
diff --git a/arch/h8300/kernel/entry.S b/arch/h8300/kernel/entry.S
index c6e289b5f1f2..42db87c17917 100644
--- a/arch/h8300/kernel/entry.S
+++ b/arch/h8300/kernel/entry.S
@@ -17,7 +17,6 @@ 
 #include <linux/sys.h>
 #include <asm/unistd.h>
 #include <asm/setup.h>
-#include <asm/segment.h>
 #include <asm/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
diff --git a/arch/h8300/kernel/head_ram.S b/arch/h8300/kernel/head_ram.S
index dbf8429f5fab..489462f0ee57 100644
--- a/arch/h8300/kernel/head_ram.S
+++ b/arch/h8300/kernel/head_ram.S
@@ -4,7 +4,6 @@ 
 #include <linux/init.h>
 #include <asm/unistd.h>
 #include <asm/setup.h>
-#include <asm/segment.h>
 #include <asm/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
diff --git a/arch/h8300/mm/init.c b/arch/h8300/mm/init.c
index f7bf4693e3b2..9fa13312720a 100644
--- a/arch/h8300/mm/init.c
+++ b/arch/h8300/mm/init.c
@@ -34,7 +34,6 @@ 
 #include <linux/gfp.h>
 
 #include <asm/setup.h>
-#include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/sections.h>
 
@@ -71,11 +70,6 @@  void __init paging_init(void)
 		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 		      __func__, PAGE_SIZE, PAGE_SIZE);
 
-	/*
-	 * Set up SFC/DFC registers (user data space).
-	 */
-	set_fs(USER_DS);
-
 	pr_debug("before free_area_init\n");
 
 	pr_debug("free_area_init -> start_mem is %#lx\nvirtual_end is %#lx\n",
diff --git a/arch/h8300/mm/memory.c b/arch/h8300/mm/memory.c
index 4a60e2b5eb96..c950571064d2 100644
--- a/arch/h8300/mm/memory.c
+++ b/arch/h8300/mm/memory.c
@@ -24,7 +24,6 @@ 
 #include <linux/types.h>
 
 #include <asm/setup.h>
-#include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/traps.h>
 #include <asm/io.h>
diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index 15dd8f38b698..54eadf265178 100644
--- a/arch/hexagon/Kconfig
+++ b/arch/hexagon/Kconfig
@@ -30,7 +30,6 @@  config HEXAGON
 	select GENERIC_CLOCKEVENTS_BROADCAST
 	select MODULES_USE_ELF_RELA
 	select GENERIC_CPU_DEVICES
-	select SET_FS
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select TRACE_IRQFLAGS_SUPPORT
 	help
diff --git a/arch/hexagon/include/asm/thread_info.h b/arch/hexagon/include/asm/thread_info.h
index 535976665bf0..e90f280b9ce3 100644
--- a/arch/hexagon/include/asm/thread_info.h
+++ b/arch/hexagon/include/asm/thread_info.h
@@ -22,10 +22,6 @@ 
 
 #ifndef __ASSEMBLY__
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 /*
  * This is union'd with the "bottom" of the kernel stack.
  * It keeps track of thread info which is handy for routines
@@ -37,7 +33,6 @@  struct thread_info {
 	unsigned long		flags;          /* low level flags */
 	__u32                   cpu;            /* current cpu */
 	int                     preempt_count;  /* 0=>preemptible,<0=>BUG */
-	mm_segment_t            addr_limit;     /* segmentation sux */
 	/*
 	 * used for syscalls somehow;
 	 * seems to have a function pointer and four arguments
@@ -66,7 +61,6 @@  struct thread_info {
 	.flags          = 0,                    \
 	.cpu            = 0,                    \
 	.preempt_count  = 1,                    \
-	.addr_limit     = KERNEL_DS,            \
 	.sp = 0,				\
 	.regs = NULL,			\
 }
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index 232dfd8956aa..dfa6b2757c05 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -105,7 +105,6 @@  int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
 	/*
 	 * Parent sees new pid -- not necessary, not even possible at
 	 * this point in the fork process
-	 * Might also want to set things like ti->addr_limit
 	 */
 
 	return 0;
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 59798e43cdb0..1fb1cec087b7 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -42,7 +42,6 @@  config MICROBLAZE
 	select CPU_NO_EFFICIENT_FFS
 	select MMU_GATHER_NO_RANGE
 	select SPARSE_IRQ
-	select SET_FS
 	select ZONE_DMA
 	select TRACE_IRQFLAGS_SUPPORT
 
diff --git a/arch/microblaze/include/asm/thread_info.h b/arch/microblaze/include/asm/thread_info.h
index 44f5ca331862..a0ddd2a36fb9 100644
--- a/arch/microblaze/include/asm/thread_info.h
+++ b/arch/microblaze/include/asm/thread_info.h
@@ -56,17 +56,12 @@  struct cpu_context {
 	__u32	fsr;
 };
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 struct thread_info {
 	struct task_struct	*task; /* main task structure */
 	unsigned long		flags; /* low level flags */
 	unsigned long		status; /* thread-synchronous flags */
 	__u32			cpu; /* current CPU */
 	__s32			preempt_count; /* 0 => preemptable,< 0 => BUG*/
-	mm_segment_t		addr_limit; /* thread address space */
 
 	struct cpu_context	cpu_context;
 };
@@ -80,7 +75,6 @@  struct thread_info {
 	.flags		= 0,			\
 	.cpu		= 0,			\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\
-	.addr_limit	= KERNEL_DS,		\
 }
 
 /* how to get the thread information struct from C */
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index dd82e90adb52..ea0c1f11035f 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -15,30 +15,6 @@ 
 #include <linux/pgtable.h>
 #include <asm/extable.h>
 #include <linux/string.h>
-
-/*
- * On Microblaze the fs value is actually the top of the corresponding
- * address space.
- *
- * The fs value determines whether argument validity checking should be
- * performed or not. If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- *
- * For non-MMU arch like Microblaze, KERNEL_DS and USER_DS is equal.
- */
-# define MAKE_MM_SEG(s)       ((mm_segment_t) { (s) })
-
-#  define KERNEL_DS	MAKE_MM_SEG(0xFFFFFFFF)
-#  define USER_DS	MAKE_MM_SEG(TASK_SIZE - 1)
-
-# define get_fs()	(current_thread_info()->addr_limit)
-# define set_fs(val)	(current_thread_info()->addr_limit = (val))
-# define user_addr_max() get_fs().seg
-
-# define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
-
 #include <asm-generic/access_ok.h>
 
 # define __FIXUP_SECTION	".section .fixup,\"ax\"\n"
diff --git a/arch/microblaze/kernel/asm-offsets.c b/arch/microblaze/kernel/asm-offsets.c
index b77dd188dec4..47ee409508b1 100644
--- a/arch/microblaze/kernel/asm-offsets.c
+++ b/arch/microblaze/kernel/asm-offsets.c
@@ -86,7 +86,6 @@  int main(int argc, char *argv[])
 	/* struct thread_info */
 	DEFINE(TI_TASK, offsetof(struct thread_info, task));
 	DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
-	DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit));
 	DEFINE(TI_CPU_CONTEXT, offsetof(struct thread_info, cpu_context));
 	DEFINE(TI_PREEMPT_COUNT, offsetof(struct thread_info, preempt_count));
 	BLANK();
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 5e2b91c1e8ce..1b944d319d73 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -18,7 +18,6 @@ 
 #include <linux/tick.h>
 #include <linux/bitops.h>
 #include <linux/ptrace.h>
-#include <linux/uaccess.h> /* for USER_DS macros */
 #include <asm/cacheflush.h>
 
 void show_regs(struct pt_regs *regs)
diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index 4d1421b18734..013249430fa3 100644
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -44,7 +44,6 @@  config NDS32
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_DYNAMIC_FTRACE
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 	help
 	  Andes(nds32) Linux support.
diff --git a/arch/nds32/include/asm/thread_info.h b/arch/nds32/include/asm/thread_info.h
index d3967ad184f0..bd8f81cf2ce5 100644
--- a/arch/nds32/include/asm/thread_info.h
+++ b/arch/nds32/include/asm/thread_info.h
@@ -16,8 +16,6 @@  struct task_struct;
 #include <asm/ptrace.h>
 #include <asm/types.h>
 
-typedef unsigned long mm_segment_t;
-
 /*
  * low level task data that entry.S needs immediate access to.
  * __switch_to() assumes cpu_context follows immediately after cpu_domain.
@@ -25,12 +23,10 @@  typedef unsigned long mm_segment_t;
 struct thread_info {
 	unsigned long flags;	/* low level flags */
 	__s32 preempt_count;	/* 0 => preemptable, <0 => bug */
-	mm_segment_t addr_limit;	/* address limit */
 };
 #define INIT_THREAD_INFO(tsk)						\
 {									\
 	.preempt_count	= INIT_PREEMPT_COUNT,				\
-	.addr_limit	= KERNEL_DS,					\
 }
 #define thread_saved_pc(tsk) ((unsigned long)(tsk->thread.cpu_context.pc))
 #define thread_saved_fp(tsk) ((unsigned long)(tsk->thread.cpu_context.fp))
diff --git a/arch/nds32/include/asm/uaccess.h b/arch/nds32/include/asm/uaccess.h
index 832d642a4068..377548d4451a 100644
--- a/arch/nds32/include/asm/uaccess.h
+++ b/arch/nds32/include/asm/uaccess.h
@@ -11,6 +11,7 @@ 
 #include <asm/errno.h>
 #include <asm/memory.h>
 #include <asm/types.h>
+#include <asm-generic/access_ok.h>
 
 #define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"
 
@@ -33,20 +34,6 @@  struct exception_table_entry {
 
 extern int fixup_exception(struct pt_regs *regs);
 
-#define KERNEL_DS 	((mm_segment_t) { ~0UL })
-#define USER_DS		((mm_segment_t) {TASK_SIZE - 1})
-
-#define get_fs()	(current_thread_info()->addr_limit)
-#define user_addr_max	get_fs
-#define uaccess_kernel() (get_fs() == KERNEL_DS)
-
-static inline void set_fs(mm_segment_t fs)
-{
-	current_thread_info()->addr_limit = fs;
-}
-
-#include <asm-generic/access_ok.h>
-
 /*
  * Single-value transfer routines.  They automatically use the right
  * size if we just have the right pointer type.  Note that the functions
diff --git a/arch/nds32/mm/alignment.c b/arch/nds32/mm/alignment.c
index 1eb7ded6992b..9c2c0a454da8 100644
--- a/arch/nds32/mm/alignment.c
+++ b/arch/nds32/mm/alignment.c
@@ -512,7 +512,6 @@  int do_unaligned_access(unsigned long addr, struct pt_regs *regs)
 {
 	unsigned long inst;
 	int ret = -EFAULT;
-	mm_segment_t seg;
 
 	inst = get_inst(regs->ipc);
 
@@ -520,12 +519,10 @@  int do_unaligned_access(unsigned long addr, struct pt_regs *regs)
 	      "Faulting addr: 0x%08lx, pc: 0x%08lx [inst: 0x%08lx ]\n", addr,
 	      regs->ipc, inst);
 
-	seg = force_uaccess_begin();
 	if (inst & NDS32_16BIT_INSTRUCTION)
 		ret = do_16((inst >> 16) & 0xffff, regs);
 	else
 		ret = do_32(inst, regs);
-	force_uaccess_end(seg);
 
 	return ret;
 }
diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
index 33fd06f5fa41..4167f1eb4cd8 100644
--- a/arch/nios2/Kconfig
+++ b/arch/nios2/Kconfig
@@ -24,7 +24,6 @@  config NIOS2
 	select USB_ARCH_HAS_HCD if USB_SUPPORT
 	select CPU_NO_EFFICIENT_FFS
 	select MMU_GATHER_NO_RANGE if MMU
-	select SET_FS
 
 config GENERIC_CSUM
 	def_bool y
diff --git a/arch/nios2/include/asm/thread_info.h b/arch/nios2/include/asm/thread_info.h
index 272d2c72a727..bcc0e9915ebd 100644
--- a/arch/nios2/include/asm/thread_info.h
+++ b/arch/nios2/include/asm/thread_info.h
@@ -26,10 +26,6 @@ 
 
 #ifndef __ASSEMBLY__
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 /*
  * low level task data that entry.S needs immediate access to
  * - this struct should fit entirely inside of one cache line
@@ -42,10 +38,6 @@  struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	__u32			cpu;		/* current CPU */
 	int			preempt_count;	/* 0 => preemptable,<0 => BUG */
-	mm_segment_t		addr_limit;	/* thread address space:
-						  0-0x7FFFFFFF for user-thead
-						  0-0xFFFFFFFF for kernel-thread
-						*/
 	struct pt_regs		*regs;
 };
 
@@ -60,7 +52,6 @@  struct thread_info {
 	.flags		= 0,			\
 	.cpu		= 0,			\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\
-	.addr_limit	= KERNEL_DS,		\
 }
 
 /* how to get the thread information struct from C */
diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h
index 9a7658df7f8d..6d364e459458 100644
--- a/arch/nios2/include/asm/uaccess.h
+++ b/arch/nios2/include/asm/uaccess.h
@@ -18,18 +18,6 @@ 
 #include <asm/page.h>
 
 #include <asm/extable.h>
-
-/*
- * Segment stuff
- */
-#define MAKE_MM_SEG(s)		((mm_segment_t) { (s) })
-#define USER_DS			MAKE_MM_SEG(0x80000000UL)
-#define KERNEL_DS		MAKE_MM_SEG(0)
-
-
-#define get_fs()		(current_thread_info()->addr_limit)
-#define set_fs(seg)		(current_thread_info()->addr_limit = (seg))
-
 #include <asm-generic/access_ok.h>
 
 # define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index f724b3f1aeed..0d68adf6e02b 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -36,7 +36,6 @@  config OPENRISC
 	select ARCH_WANT_FRAME_POINTERS
 	select GENERIC_IRQ_MULTI_HANDLER
 	select MMU_GATHER_NO_RANGE if MMU
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 
 config CPU_BIG_ENDIAN
diff --git a/arch/openrisc/include/asm/thread_info.h b/arch/openrisc/include/asm/thread_info.h
index 659834ab87fa..4af3049c34c2 100644
--- a/arch/openrisc/include/asm/thread_info.h
+++ b/arch/openrisc/include/asm/thread_info.h
@@ -40,18 +40,12 @@ 
  */
 #ifndef __ASSEMBLY__
 
-typedef unsigned long mm_segment_t;
-
 struct thread_info {
 	struct task_struct	*task;		/* main task structure */
 	unsigned long		flags;		/* low level flags */
 	__u32			cpu;		/* current CPU */
 	__s32			preempt_count; /* 0 => preemptable, <0 => BUG */
 
-	mm_segment_t		addr_limit; /* thread address space:
-					       0-0x7FFFFFFF for user-thead
-					       0-0xFFFFFFFF for kernel-thread
-					     */
 	__u8			supervisor_stack[0];
 
 	/* saved context data */
@@ -71,7 +65,6 @@  struct thread_info {
 	.flags		= 0,				\
 	.cpu		= 0,				\
 	.preempt_count	= INIT_PREEMPT_COUNT,		\
-	.addr_limit	= KERNEL_DS,			\
 	.ksp            = 0,                            \
 }
 
diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
index 8f049ec99b3e..d6500a374e18 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -22,29 +22,6 @@ 
 #include <linux/string.h>
 #include <asm/page.h>
 #include <asm/extable.h>
-
-/*
- * The fs value determines whether argument validity checking should be
- * performed or not.  If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
-
-/* addr_limit is the maximum accessible address for the task. we misuse
- * the KERNEL_DS and USER_DS values to both assign and compare the
- * addr_limit values through the equally misnamed get/set_fs macros.
- * (see above)
- */
-
-#define KERNEL_DS	(~0UL)
-
-#define USER_DS		(TASK_SIZE)
-#define get_fs()	(current_thread_info()->addr_limit)
-#define set_fs(x)	(current_thread_info()->addr_limit = (x))
-
-#define uaccess_kernel()	(get_fs() == KERNEL_DS)
-
 #include <asm-generic/access_ok.h>
 
 /*
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 1cab1b284f1a..875388835a58 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -46,7 +46,6 @@  config SPARC
 	select LOCKDEP_SMALL if LOCKDEP
 	select NEED_DMA_MAP_STATE
 	select NEED_SG_DMA_LENGTH
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 
 config SPARC32
@@ -100,6 +99,7 @@  config SPARC64
 	select HAVE_SETUP_PER_CPU_AREA
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
 	select NEED_PER_CPU_PAGE_FIRST_CHUNK
+	select SET_FS
 
 config ARCH_PROC_KCORE_TEXT
 	def_bool y
diff --git a/arch/sparc/include/asm/processor_32.h b/arch/sparc/include/asm/processor_32.h
index 647bf0ac7beb..b26c35336b51 100644
--- a/arch/sparc/include/asm/processor_32.h
+++ b/arch/sparc/include/asm/processor_32.h
@@ -32,10 +32,6 @@  struct fpq {
 };
 #endif
 
-typedef struct {
-	int seg;
-} mm_segment_t;
-
 /* The Sparc processor specific thread struct. */
 struct thread_struct {
 	struct pt_regs *kregs;
@@ -50,11 +46,9 @@  struct thread_struct {
 	unsigned long   fsr;
 	unsigned long   fpqdepth;
 	struct fpq	fpqueue[16];
-	mm_segment_t current_ds;
 };
 
 #define INIT_THREAD  { \
-	.current_ds = KERNEL_DS, \
 	.kregs = (struct pt_regs *)(init_stack+THREAD_SIZE)-1 \
 }
 
diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h
index 367747116260..9fd6c53644b6 100644
--- a/arch/sparc/include/asm/uaccess_32.h
+++ b/arch/sparc/include/asm/uaccess_32.h
@@ -12,19 +12,6 @@ 
 #include <linux/string.h>
 
 #include <asm/processor.h>
-
-/* Sparc is not segmented, however we need to be able to fool access_ok()
- * when doing system calls from kernel mode legitimately.
- *
- * "For historical reasons, these macros are grossly misnamed." -Linus
- */
-
-#define KERNEL_DS   ((mm_segment_t) { 0 })
-#define USER_DS     ((mm_segment_t) { -1 })
-
-#define get_fs()	(current->thread.current_ds)
-#define set_fs(val)	((current->thread.current_ds) = (val))
-
 #include <asm-generic/access_ok.h>
 
 /* Uh, these should become the main single-value transfer routines..
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 2dc0bf9fe62e..88c0c14aaff0 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -300,7 +300,6 @@  int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
 		extern int nwindows;
 		unsigned long psr;
 		memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
-		p->thread.current_ds = KERNEL_DS;
 		ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
 		childregs->u_regs[UREG_G1] = sp; /* function */
 		childregs->u_regs[UREG_G2] = arg;
@@ -311,7 +310,6 @@  int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
 	}
 	memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
 	childregs->u_regs[UREG_FP] = sp;
-	p->thread.current_ds = USER_DS;
 	ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
 	ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
 	ti->kwim = current->thread.fork_kwim;
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 8ac599aa6d99..09f7616a0b46 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -40,7 +40,6 @@  config XTENSA
 	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select PERF_USE_VMALLOC
-	select SET_FS
 	select TRACE_IRQFLAGS_SUPPORT
 	select VIRT_TO_BUS
 	help
diff --git a/arch/xtensa/include/asm/asm-uaccess.h b/arch/xtensa/include/asm/asm-uaccess.h
index 7f6cf4151843..7cec869136e3 100644
--- a/arch/xtensa/include/asm/asm-uaccess.h
+++ b/arch/xtensa/include/asm/asm-uaccess.h
@@ -23,76 +23,6 @@ 
 #include <asm/asm-offsets.h>
 #include <asm/processor.h>
 
-/*
- * These assembly macros mirror the C macros in asm/uaccess.h.  They
- * should always have identical functionality.  See
- * arch/xtensa/kernel/sys.S for usage.
- */
-
-#define KERNEL_DS	0
-#define USER_DS		1
-
-/*
- * get_fs reads current->thread.current_ds into a register.
- * On Entry:
- * 	<ad>	anything
- * 	<sp>	stack
- * On Exit:
- * 	<ad>	contains current->thread.current_ds
- */
-	.macro	get_fs	ad, sp
-	GET_CURRENT(\ad,\sp)
-#if THREAD_CURRENT_DS > 1020
-	addi	\ad, \ad, TASK_THREAD
-	l32i	\ad, \ad, THREAD_CURRENT_DS - TASK_THREAD
-#else
-	l32i	\ad, \ad, THREAD_CURRENT_DS
-#endif
-	.endm
-
-/*
- * set_fs sets current->thread.current_ds to some value.
- * On Entry:
- *	<at>	anything (temp register)
- *	<av>	value to write
- *	<sp>	stack
- * On Exit:
- *	<at>	destroyed (actually, current)
- *	<av>	preserved, value to write
- */
-	.macro	set_fs	at, av, sp
-	GET_CURRENT(\at,\sp)
-	s32i	\av, \at, THREAD_CURRENT_DS
-	.endm
-
-/*
- * kernel_ok determines whether we should bypass addr/size checking.
- * See the equivalent C-macro version below for clarity.
- * On success, kernel_ok branches to a label indicated by parameter
- * <success>.  This implies that the macro falls through to the next
- * insruction on an error.
- *
- * Note that while this macro can be used independently, we designed
- * in for optimal use in the access_ok macro below (i.e., we fall
- * through on error).
- *
- * On Entry:
- * 	<at>		anything (temp register)
- * 	<success>	label to branch to on success; implies
- * 			fall-through macro on error
- * 	<sp>		stack pointer
- * On Exit:
- * 	<at>		destroyed (actually, current->thread.current_ds)
- */
-
-#if ((KERNEL_DS != 0) || (USER_DS == 0))
-# error Assembly macro kernel_ok fails
-#endif
-	.macro	kernel_ok  at, sp, success
-	get_fs	\at, \sp
-	beqz	\at, \success
-	.endm
-
 /*
  * user_ok determines whether the access to user-space memory is allowed.
  * See the equivalent C-macro version below for clarity.
@@ -147,7 +77,6 @@ 
  * 	<at>	destroyed
  */
 	.macro	access_ok  aa, as, at, sp, error
-	kernel_ok  \at, \sp, .Laccess_ok_\@
 	user_ok    \aa, \as, \at, \error
 .Laccess_ok_\@:
 	.endm
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 37d3e9887fe7..abad7c3df46f 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -152,18 +152,12 @@ 
  */
 #define SPILL_SLOT_CALL12(sp, reg) (*(((unsigned long *)(sp)) - 16 + (reg)))
 
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
 struct thread_struct {
 
 	/* kernel's return address and stack pointer for context switching */
 	unsigned long ra; /* kernel's a0: return address and window call size */
 	unsigned long sp; /* kernel's a1: stack pointer */
 
-	mm_segment_t current_ds;    /* see uaccess.h for example uses */
-
 	/* struct xtensa_cpuinfo info; */
 
 	unsigned long bad_vaddr; /* last user fault */
@@ -186,7 +180,6 @@  struct thread_struct {
 {									\
 	ra:		0, 						\
 	sp:		sizeof(init_stack) + (long) &init_stack,	\
-	current_ds:	{0},						\
 	/*info:		{0}, */						\
 	bad_vaddr:	0,						\
 	bad_uaddr:	0,						\
diff --git a/arch/xtensa/include/asm/thread_info.h b/arch/xtensa/include/asm/thread_info.h
index a312333a9add..f6fcbba1d02f 100644
--- a/arch/xtensa/include/asm/thread_info.h
+++ b/arch/xtensa/include/asm/thread_info.h
@@ -52,8 +52,6 @@  struct thread_info {
 	__u32			cpu;		/* current CPU */
 	__s32			preempt_count;	/* 0 => preemptable,< 0 => BUG*/
 
-	mm_segment_t		addr_limit;	/* thread address space */
-
 	unsigned long		cpenable;
 #if XCHAL_HAVE_EXCLUSIVE
 	/* result of the most recent exclusive store */
@@ -81,7 +79,6 @@  struct thread_info {
 	.flags		= 0,			\
 	.cpu		= 0,			\
 	.preempt_count	= INIT_PREEMPT_COUNT,	\
-	.addr_limit	= KERNEL_DS,		\
 }
 
 /* how to get the thread information struct from C */
diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index 0edd9e4b23d0..56aec6d504fe 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -19,22 +19,6 @@ 
 #include <linux/prefetch.h>
 #include <asm/types.h>
 #include <asm/extable.h>
-
-/*
- * The fs value determines whether argument validity checking should
- * be performed or not.  If get_fs() == USER_DS, checking is
- * performed, with get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons (Data Segment Register?), these macros are
- * grossly misnamed.
- */
-
-#define KERNEL_DS	((mm_segment_t) { 0 })
-#define USER_DS		((mm_segment_t) { 1 })
-
-#define get_fs()	(current->thread.current_ds)
-#define set_fs(val)	(current->thread.current_ds = (val))
-
 #include <asm-generic/access_ok.h>
 
 /*
diff --git a/arch/xtensa/kernel/asm-offsets.c b/arch/xtensa/kernel/asm-offsets.c
index dc5c83cad9be..f1fd1390d069 100644
--- a/arch/xtensa/kernel/asm-offsets.c
+++ b/arch/xtensa/kernel/asm-offsets.c
@@ -87,7 +87,6 @@  int main(void)
 	OFFSET(TI_STSTUS, thread_info, status);
 	OFFSET(TI_CPU, thread_info, cpu);
 	OFFSET(TI_PRE_COUNT, thread_info, preempt_count);
-	OFFSET(TI_ADDR_LIMIT, thread_info, addr_limit);
 
 	/* struct thread_info (offset from start_struct) */
 	DEFINE(THREAD_RA, offsetof (struct task_struct, thread.ra));
@@ -108,8 +107,6 @@  int main(void)
 #endif
 	DEFINE(THREAD_XTREGS_USER, offsetof (struct thread_info, xtregs_user));
 	DEFINE(XTREGS_USER_SIZE, sizeof(xtregs_user_t));
-	DEFINE(THREAD_CURRENT_DS, offsetof (struct task_struct, \
-	       thread.current_ds));
 
 	/* struct mm_struct */
 	DEFINE(MM_USERS, offsetof(struct mm_struct, mm_users));
diff --git a/include/asm-generic/uaccess.h b/include/asm-generic/uaccess.h
index ebc685dc8d74..a5be9e61a2a2 100644
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -8,6 +8,7 @@ 
  * address space, e.g. all NOMMU machines.
  */
 #include <linux/string.h>
+#include <asm-generic/access_ok.h>
 
 #ifdef CONFIG_UACCESS_MEMCPY
 #include <asm/unaligned.h>
@@ -94,30 +95,6 @@  raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 #define INLINE_COPY_TO_USER
 #endif /* CONFIG_UACCESS_MEMCPY */
 
-#ifdef CONFIG_SET_FS
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-
-#ifndef KERNEL_DS
-#define KERNEL_DS	MAKE_MM_SEG(~0UL)
-#endif
-
-#ifndef USER_DS
-#define USER_DS		MAKE_MM_SEG(TASK_SIZE - 1)
-#endif
-
-#ifndef get_fs
-#define get_fs()	(current_thread_info()->addr_limit)
-
-static inline void set_fs(mm_segment_t fs)
-{
-	current_thread_info()->addr_limit = fs;
-}
-#endif
-
-#endif /* CONFIG_SET_FS */
-
-#include <asm-generic/access_ok.h>
-
 /*
  * These are the main single-value transfer routines.  They automatically
  * use the right size if we just have the right pointer type.