[PATCH 07/15] x86, fpu: rework XSTATE_* macros to remove magic '2'

[Dave Hansen <dave@sr71.net>]

From: Dave Hansen <dave.hansen@linux.intel.com>

The 'xstate.c' code has a bunch of references to '2'.  This
is because we have a lot more work to do for the "extended"
xstates than the "legacy" ones and state component 2 is the
first "extended" state.

This patch replaces all of the instances of '2' with
FIRST_EXTENDED_XFEATURE, which clearly explains what is
going on.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
---

 b/arch/x86/include/asm/fpu/types.h |    2 ++
 b/arch/x86/kernel/fpu/xstate.c     |   13 +++++++------
 2 files changed, 9 insertions(+), 6 deletions(-)

diff -puN arch/x86/include/asm/fpu/types.h~remove-hard-coded-values arch/x86/include/asm/fpu/types.h
--- a/arch/x86/include/asm/fpu/types.h~remove-hard-coded-values	2015-09-02 15:52:53.495053333 -0700
+++ b/arch/x86/include/asm/fpu/types.h	2015-09-02 16:24:49.864133927 -0700
@@ -126,6 +126,8 @@ enum xfeature {
 					 | XFEATURE_MASK_ZMM_Hi256 \
 					 | XFEATURE_MASK_Hi16_ZMM)
 
+#define FIRST_EXTENDED_XFEATURE	XFEATURE_YMM
+
 /*
  * There are 16x 256-bit AVX registers named YMM0-YMM15.
  * The low 128 bits are aliased to the 16 SSE registers (XMM0-XMM15)
diff -puN arch/x86/kernel/fpu/xstate.c~remove-hard-coded-values arch/x86/kernel/fpu/xstate.c
--- a/arch/x86/kernel/fpu/xstate.c~remove-hard-coded-values	2015-09-02 15:52:53.496053379 -0700
+++ b/arch/x86/kernel/fpu/xstate.c	2015-09-02 16:25:38.017321147 -0700
@@ -200,7 +200,7 @@ static void __init setup_xstate_features
 
 	xfeatures_nr = fls64(xfeatures_mask);
 
-	for (leaf = 2; leaf < xfeatures_nr; leaf++) {
+	for (leaf = FIRST_EXTENDED_XFEATURE; leaf < xfeatures_nr; leaf++) {
 		cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
 
 		xstate_offsets[leaf] = ebx;
@@ -252,7 +252,7 @@ static void __init setup_xstate_comp(voi
 	xstate_comp_offsets[1] = offsetof(struct fxregs_state, xmm_space);
 
 	if (!cpu_has_xsaves) {
-		for (i = 2; i < xfeatures_nr; i++) {
+		for (i = FIRST_EXTENDED_XFEATURE; i < xfeatures_nr; i++) {
 			if (test_bit(i, (unsigned long *)&xfeatures_mask)) {
 				xstate_comp_offsets[i] = xstate_offsets[i];
 				xstate_comp_sizes[i] = xstate_sizes[i];
@@ -261,15 +261,16 @@ static void __init setup_xstate_comp(voi
 		return;
 	}
 
-	xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
+		FXSAVE_SIZE + XSAVE_HDR_SIZE;
 
-	for (i = 2; i < xfeatures_nr; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE; i < xfeatures_nr; i++) {
 		if (test_bit(i, (unsigned long *)&xfeatures_mask))
 			xstate_comp_sizes[i] = xstate_sizes[i];
 		else
 			xstate_comp_sizes[i] = 0;
 
-		if (i > 2)
+		if (i > FIRST_EXTENDED_XFEATURE)
 			xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
 					+ xstate_comp_sizes[i-1];
 
@@ -325,7 +326,7 @@ static unsigned int __init calculate_xst
 	}
 
 	calculated_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
-	for (i = 2; i < 64; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE; i < 64; i++) {
 		if (test_bit(i, (unsigned long *)&xfeatures_mask)) {
 			cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 			calculated_xstate_size += eax;
_