x86/uaccess: Move thread_info::uaccess_err and thread_info::sig_on_uaccess_err to thread_struct

struct thread_info is a legacy mess. To prepare for its partial removal,
move the uaccess control fields out -- they're straightforward.

Signed-off-by: Andy Lutomirski <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: Denys Vlasenko <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Josh Poimboeuf <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/entry/vsyscall/vsyscall_64.c

···
 	 * With a real vsyscall, page faults cause SIGSEGV.  We want to
 	 * preserve that behavior to make writing exploits harder.
 	 */
-	prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error;
-	current_thread_info()->sig_on_uaccess_error = 1;
+	prev_sig_on_uaccess_error = current->thread.sig_on_uaccess_error;
+	current->thread.sig_on_uaccess_error = 1;
 
 	ret = -EFAULT;
 	switch (vsyscall_nr) {
···
 		break;
 	}
 
-	current_thread_info()->sig_on_uaccess_error = prev_sig_on_uaccess_error;
+	current->thread.sig_on_uaccess_error = prev_sig_on_uaccess_error;
 
 check_fault:
 	if (ret == -EFAULT) {

arch/x86/include/asm/processor.h

···
 	/* Max allowed port in the bitmap, in bytes: */
 	unsigned		io_bitmap_max;
 
+	unsigned int		sig_on_uaccess_error:1;
+	unsigned int		uaccess_err:1;	/* uaccess failed */
+
 	/* Floating point and extended processor state */
 	struct fpu		fpu;
 	/*

arch/x86/include/asm/thread_info.h

···
 	__u32			status;		/* thread synchronous flags */
 	__u32			cpu;		/* current CPU */
 	mm_segment_t		addr_limit;
-	unsigned int		sig_on_uaccess_error:1;
-	unsigned int		uaccess_err:1;	/* uaccess failed */
 };
 
 #define INIT_THREAD_INFO(tsk)			\

arch/x86/include/asm/uaccess.h

···
  * uaccess_try and catch
  */
 #define uaccess_try	do {						\
-	current_thread_info()->uaccess_err = 0;				\
+	current->thread.uaccess_err = 0;				\
 	__uaccess_begin();						\
 	barrier();
 
 #define uaccess_catch(err)						\
 	__uaccess_end();						\
-	(err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);	\
+	(err) |= (current->thread.uaccess_err ? -EFAULT : 0);		\
 } while (0)
 
 /**

arch/x86/mm/extable.c

···
 		   struct pt_regs *regs, int trapnr)
 {
 	/* Special hack for uaccess_err */
-	current_thread_info()->uaccess_err = 1;
+	current->thread.uaccess_err = 1;
 	regs->ip = ex_fixup_addr(fixup);
 	return true;
 }

arch/x86/mm/fault.c

···
 		 * In this case we need to make sure we're not recursively
 		 * faulting through the emulate_vsyscall() logic.
 		 */
-		if (current_thread_info()->sig_on_uaccess_error && signal) {
+		if (current->thread.sig_on_uaccess_error && signal) {
 			tsk->thread.trap_nr = X86_TRAP_PF;
 			tsk->thread.error_code = error_code | PF_USER;
 			tsk->thread.cr2 = address;