uaccess: remove CONFIG_SET_FS

There are no remaining callers of set_fs(), so CONFIG_SET_FS
can be removed globally, along with the thread_info field and
any references to it.

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

As CONFIG_SET_FS is now gone, drop all remaining references to
set_fs()/get_fs(), mm_segment_t, user_addr_max() and uaccess_kernel().

Acked-by: Sam Ravnborg <sam@ravnborg.org> # for sparc32 changes
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Tested-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com> # for arc changes
Acked-by: Stafford Horne <shorne@gmail.com> # [openrisc, asm-generic]
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

5 files changed, 3 insertions, 75 deletions

diff --git a/include/asm-generic/access_ok.h b/include/asm-generic/access_ok.h
index d38cc5dad65b..2866ae61b1cd 100644
--- a/include/asm-generic/access_ok.h
+++ b/include/asm-generic/access_ok.h
@@ -16,18 +16,6 @@
 #define TASK_SIZE_MAX			TASK_SIZE
 #endif
 
-#ifndef uaccess_kernel
-#ifdef CONFIG_SET_FS
-#define uaccess_kernel()		(get_fs().seg == KERNEL_DS.seg)
-#else
-#define uaccess_kernel()		(0)
-#endif
-#endif
-
-#ifndef user_addr_max
-#define user_addr_max()			(uaccess_kernel() ? ~0UL : TASK_SIZE_MAX)
-#endif
-
 #ifndef __access_ok
 /*
  * 'size' is a compile-time constant for most callers, so optimize for
@@ -42,7 +30,7 @@
  */
 static inline int __access_ok(const void __user *ptr, unsigned long size)
 {
-	unsigned long limit = user_addr_max();
+	unsigned long limit = TASK_SIZE_MAX;
 	unsigned long addr = (unsigned long)ptr;
 
 	if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||
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.
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 819c0cb00b6d..a34b0f9a9972 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -290,10 +290,6 @@ static inline void addr_limit_user_check(void)
 		return;
 #endif
 
-	if (CHECK_DATA_CORRUPTION(uaccess_kernel(),
-				  "Invalid address limit on user-mode return"))
-		force_sig(SIGKILL);
-
 #ifdef TIF_FSCHECK
 	clear_thread_flag(TIF_FSCHECK);
 #endif
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 2c31667e62e0..2421a41f3a8e 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -10,39 +10,6 @@
 
 #include <asm/uaccess.h>
 
-#ifdef CONFIG_SET_FS
-/*
- * Force the uaccess routines to be wired up for actual userspace access,
- * overriding any possible set_fs(KERNEL_DS) still lingering around.  Undone
- * using force_uaccess_end below.
- */
-static inline mm_segment_t force_uaccess_begin(void)
-{
-	mm_segment_t fs = get_fs();
-
-	set_fs(USER_DS);
-	return fs;
-}
-
-static inline void force_uaccess_end(mm_segment_t oldfs)
-{
-	set_fs(oldfs);
-}
-#else /* CONFIG_SET_FS */
-typedef struct {
-	/* empty dummy */
-} mm_segment_t;
-
-static inline mm_segment_t force_uaccess_begin(void)
-{
-	return (mm_segment_t) { };
-}
-
-static inline void force_uaccess_end(mm_segment_t oldfs)
-{
-}
-#endif /* CONFIG_SET_FS */
-
 /*
  * Architectures should provide two primitives (raw_copy_{to,from}_user())
  * and get rid of their private instances of copy_{to,from}_user() and
diff --git a/include/rdma/ib.h b/include/rdma/ib.h
index 83139b9ce409..f7c185ff7a11 100644
--- a/include/rdma/ib.h
+++ b/include/rdma/ib.h
@@ -75,7 +75,7 @@ struct sockaddr_ib {
  */
 static inline bool ib_safe_file_access(struct file *filp)
 {
-	return filp->f_cred == current_cred() && !uaccess_kernel();
+	return filp->f_cred == current_cred();
 }
 
 #endif /* _RDMA_IB_H */