x86/headers: Make sigcontext pointers bit independent

Before we can eliminate the duplication between 'struct
sigcontext_32' and 'struct sigcontext_ia32', make the 'fpstate'
pointer field in 'struct sigcontext_32' bit independent.
Acked-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-12-git-send-email-mingo@kernel.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/uapi/asm/sigcontext.h

@@ -218,7 +218,7 @@ struct sigcontext_32 {
 	 * of extended memory layout. See comments at the definition of
 	 * (struct _fpx_sw_bytes)
 	 */
-	void __user			*fpstate; /* Zero when no FPU/extended context */
+	__u32				fpstate; /* Zero when no FPU/extended context */
 	__u32				oldmask;
 	__u32				cr2;
 };
@@ -258,7 +258,7 @@ struct sigcontext_64 {
 	 * of extended memory layout. See comments at the definition of
 	 * (struct _fpx_sw_bytes)
 	 */
-	void __user			*fpstate; /* Zero when no FPU/extended context */
+	__u64				fpstate; /* Zero when no FPU/extended context */
 	__u64				reserved1[8];
 };
 

arch/x86/kernel/signal.c

@@ -63,6 +63,7 @@
 
 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 {
+	unsigned long buf_val;
 	void __user *buf;
 	unsigned int tmpflags;
 	unsigned int err = 0;
@@ -107,7 +108,8 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 		regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 		regs->orig_ax = -1;		/* disable syscall checks */
 
-		get_user_ex(buf, &sc->fpstate);
+		get_user_ex(buf_val, &sc->fpstate);
+		buf = (void __user *)buf_val;
 	} get_user_catch(err);
 
 	err |= fpu__restore_sig(buf, config_enabled(CONFIG_X86_32));