x86: remove address space overrides using set_fs()

Stop providing the possibility to override the address space using
set_fs() now that there is no need for that any more.  To properly
handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on
x86 a new alternative is introduced, which just like the one in
entry_64.S has to use the hardcoded virtual address bits to escape
the fact that TASK_SIZE_MAX isn't actually a constant when 5-level
page tables are enabled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 25 deletions

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index ecefaffd15d4..a4ceda0510ea 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -13,30 +13,6 @@
 #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.
- */
-
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-
-#define KERNEL_DS	MAKE_MM_SEG(-1UL)
-#define USER_DS 	MAKE_MM_SEG(TASK_SIZE_MAX)
-
-#define get_fs()	(current->thread.addr_limit)
-static inline void set_fs(mm_segment_t fs)
-{
-	current->thread.addr_limit = fs;
-	/* On user-mode return, check fs is correct */
-	set_thread_flag(TIF_FSCHECK);
-}
-
-#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
-#define user_addr_max() (current->thread.addr_limit.seg)
-
-/*
  * Test whether a block of memory is a valid user space address.
  * Returns 0 if the range is valid, nonzero otherwise.
  */
@@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void);
 #define access_ok(addr, size)					\
 ({									\
 	WARN_ON_IN_IRQ();						\
-	likely(!__range_not_ok(addr, size, user_addr_max()));		\
+	likely(!__range_not_ok(addr, size, TASK_SIZE_MAX));		\
 })
 
 /*