x86/fpu: Get rid of using_compacted_format()

This function is pointlessly global and a complete misnomer because it's
usage is related to both supervisor state checks and compacted format
checks. Remove it and just make the conditions check the XSAVES feature.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.425493349@linutronix.de

arch/x86/include/asm/fpu/xstate.h

@@ -101,7 +101,6 @@ extern void __init update_regset_xstate_info(unsigned int size,
 					     u64 xstate_mask);
 
 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
-int using_compacted_format(void);
 int xfeature_size(int xfeature_nr);
 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);

arch/x86/kernel/fpu/xstate.c

@@ -449,20 +449,6 @@ int xfeature_size(int xfeature_nr)
 	return eax;
 }
 
-/*
- * 'XSAVES' implies two different things:
- * 1. saving of supervisor/system state
- * 2. using the compacted format
- *
- * Use this function when dealing with the compacted format so
- * that it is obvious which aspect of 'XSAVES' is being handled
- * by the calling code.
- */
-int using_compacted_format(void)
-{
-	return boot_cpu_has(X86_FEATURE_XSAVES);
-}
-
 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
 static int validate_user_xstate_header(const struct xstate_header *hdr)
 {
@@ -581,9 +567,9 @@ static void do_extra_xstate_size_checks(void)
 		check_xstate_against_struct(i);
 		/*
 		 * Supervisor state components can be managed only by
-		 * XSAVES, which is compacted-format only.
+		 * XSAVES.
 		 */
-		if (!using_compacted_format())
+		if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
 			XSTATE_WARN_ON(xfeature_is_supervisor(i));
 
 		/* Align from the end of the previous feature */
@@ -593,9 +579,9 @@ static void do_extra_xstate_size_checks(void)
 		 * The offset of a given state in the non-compacted
 		 * format is given to us in a CPUID leaf.  We check
 		 * them for being ordered (increasing offsets) in
-		 * setup_xstate_features().
+		 * setup_xstate_features(). XSAVES uses compacted format.
 		 */
-		if (!using_compacted_format())
+		if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
 			paranoid_xstate_size = xfeature_uncompacted_offset(i);
 		/*
 		 * The compacted-format offset always depends on where