x86/fpu/signal: Convert to fpstate

Convert signal related code to the new register storage mechanism in
preparation for dynamically sized buffers.

No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.607370221@linutronix.de

arch/x86/kernel/fpu/signal.c

@@ -72,13 +72,13 @@ static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf)
 {
 	if (use_fxsr()) {
-		struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
+		struct xregs_state *xsave = &tsk->thread.fpu.fpstate->regs.xsave;
 		struct user_i387_ia32_struct env;
 		struct _fpstate_32 __user *fp = buf;
 
 		fpregs_lock();
 		if (!test_thread_flag(TIF_NEED_FPU_LOAD))
-			fxsave(&tsk->thread.fpu.state.fxsave);
+			fxsave(&tsk->thread.fpu.fpstate->regs.fxsave);
 		fpregs_unlock();
 
 		convert_from_fxsr(&env, tsk);
@@ -303,7 +303,7 @@ static bool restore_fpregs_from_user(void __user *buf, u64 xrestore,
 	 * been restored from a user buffer directly.
 	 */
 	if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor())
-		os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor());
+		os_xrstor(&fpu->fpstate->regs.xsave, xfeatures_mask_supervisor());
 
 	fpregs_mark_activate();
 	fpregs_unlock();
@@ -317,6 +317,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
 	struct user_i387_ia32_struct env;
+	union fpregs_state *fpregs;
 	u64 user_xfeatures = 0;
 	bool fx_only = false;
 	bool success;
@@ -349,6 +350,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	if (__copy_from_user(&env, buf, sizeof(env)))
 		return false;
 
+	fpregs = &fpu->fpstate->regs;
 	/*
 	 * By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is
 	 * not modified on context switch and that the xstate is considered
@@ -366,7 +368,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 		 * the right place in memory. It's ia32 mode. Shrug.
 		 */
 		if (xfeatures_mask_supervisor())
-			os_xsave(&fpu->state.xsave);
+			os_xsave(&fpregs->xsave);
 		set_thread_flag(TIF_NEED_FPU_LOAD);
 	}
 	__fpu_invalidate_fpregs_state(fpu);
@@ -374,29 +376,29 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	fpregs_unlock();
 
 	if (use_xsave() && !fx_only) {
-		if (copy_sigframe_from_user_to_xstate(&fpu->state.xsave, buf_fx))
+		if (copy_sigframe_from_user_to_xstate(&fpregs->xsave, buf_fx))
 			return false;
 	} else {
-		if (__copy_from_user(&fpu->state.fxsave, buf_fx,
-				     sizeof(fpu->state.fxsave)))
+		if (__copy_from_user(&fpregs->fxsave, buf_fx,
+				     sizeof(fpregs->fxsave)))
 			return false;
 
 		if (IS_ENABLED(CONFIG_X86_64)) {
 			/* Reject invalid MXCSR values. */
-			if (fpu->state.fxsave.mxcsr & ~mxcsr_feature_mask)
+			if (fpregs->fxsave.mxcsr & ~mxcsr_feature_mask)
 				return false;
 		} else {
 			/* Mask invalid bits out for historical reasons (broken hardware). */
-			fpu->state.fxsave.mxcsr &= mxcsr_feature_mask;
+			fpregs->fxsave.mxcsr &= mxcsr_feature_mask;
 		}
 
 		/* Enforce XFEATURE_MASK_FPSSE when XSAVE is enabled */
 		if (use_xsave())
-			fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
+			fpregs->xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
 	}
 
 	/* Fold the legacy FP storage */
-	convert_to_fxsr(&fpu->state.fxsave, &env);
+	convert_to_fxsr(&fpregs->fxsave, &env);
 
 	fpregs_lock();
 	if (use_xsave()) {
@@ -411,10 +413,10 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 		 */
 		u64 mask = user_xfeatures | xfeatures_mask_supervisor();
 
-		fpu->state.xsave.header.xfeatures &= mask;
-		success = !os_xrstor_safe(&fpu->state.xsave, xfeatures_mask_all);
+		fpregs->xsave.header.xfeatures &= mask;
+		success = !os_xrstor_safe(&fpregs->xsave, xfeatures_mask_all);
 	} else {
-		success = !fxrstor_safe(&fpu->state.fxsave);
+		success = !fxrstor_safe(&fpregs->fxsave);
 	}
 
 	if (likely(success))