x86/fpu/signal: Change return code of check_xstate_in_sigframe() to boolean

__fpu_sig_restore() only needs success/fail information and no detailed
error code.
Suggested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210908132526.024024598@linutronix.de

arch/x86/kernel/fpu/signal.c

@@ -23,8 +23,8 @@ static struct _fpx_sw_bytes fx_sw_reserved_ia32 __ro_after_init;
  * Check for the presence of extended state information in the
  * user fpstate pointer in the sigcontext.
  */
-static inline int check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
-					   struct _fpx_sw_bytes *fx_sw)
+static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
+					    struct _fpx_sw_bytes *fx_sw)
 {
 	int min_xstate_size = sizeof(struct fxregs_state) +
 			      sizeof(struct xstate_header);
@@ -32,7 +32,7 @@ static inline int check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 	unsigned int magic2;
 
 	if (__copy_from_user(fx_sw, &fxbuf->sw_reserved[0], sizeof(*fx_sw)))
-		return -EFAULT;
+		return false;
 
 	/* Check for the first magic field and other error scenarios. */
 	if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
@@ -48,10 +48,10 @@ static inline int check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 	 * in the memory layout.
 	 */
 	if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size)))
-		return -EFAULT;
+		return false;
 
 	if (likely(magic2 == FP_XSTATE_MAGIC2))
-		return 0;
+		return true;
 setfx:
 	trace_x86_fpu_xstate_check_failed(&current->thread.fpu);
 
@@ -59,7 +59,7 @@ static inline int check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 	fx_sw->magic1 = 0;
 	fx_sw->xstate_size = sizeof(struct fxregs_state);
 	fx_sw->xfeatures = XFEATURE_MASK_FPSSE;
-	return 0;
+	return true;
 }
 
 /*
@@ -324,7 +324,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	if (use_xsave()) {
 		struct _fpx_sw_bytes fx_sw_user;
 
-		if (check_xstate_in_sigframe(buf_fx, &fx_sw_user))
+		if (!check_xstate_in_sigframe(buf_fx, &fx_sw_user))
 			return false;
 
 		fx_only = !fx_sw_user.magic1;