linux-kernel - [PATCH 03/11] x86, fpu: rework XSTATE

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Date:	Thu, 27 Aug 2015 10:11:03 -0700
From:	Dave Hansen <dave@...1.net>
To:	dave@...1.net
Cc:	dave.hansen@...ux.intel.com, mingo@...hat.com, x86@...nel.org,
	bp@...en8.de, fenghua.yu@...el.com, tim.c.chen@...ux.intel.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH 03/11] x86, fpu: rework XSTATE_* macros to remove magic '2'


From: Dave Hansen <dave.hansen@...ux.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_NR, which clearly explains what is
going on.


Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: x86@...nel.org
Cc: Borislav Petkov <bp@...en8.de>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: linux-kernel@...r.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	2015-08-27 10:08:01.942651168 -0700
+++ b/arch/x86/include/asm/fpu/types.h	2015-08-27 10:08:01.946651350 -0700
@@ -124,6 +124,8 @@ enum xfeature_nr {
 #define XSTATE_FPSSE		(XSTATE_FP | XSTATE_SSE)
 #define XSTATE_AVX512		(XSTATE_OPMASK | XSTATE_ZMM_Hi256 | XSTATE_Hi16_ZMM)
 
+#define FIRST_EXTENDED_XFEATURE_NR	XFEATURE_NR_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	2015-08-27 10:08:01.943651213 -0700
+++ b/arch/x86/kernel/fpu/xstate.c	2015-08-27 10:08:01.947651395 -0700
@@ -181,7 +181,7 @@ static void __init setup_xstate_features
 
 	xfeatures_nr = fls64(xfeatures_mask);
 
-	for (leaf = 2; leaf < xfeatures_nr; leaf++) {
+	for (leaf = FIRST_EXTENDED_XFEATURE_NR; leaf < xfeatures_nr; leaf++) {
 		cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
 
 		xstate_offsets[leaf] = ebx;
@@ -233,7 +233,7 @@ 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_NR; 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];
@@ -242,15 +242,16 @@ static void __init setup_xstate_comp(voi
 		return;
 	}
 
-	xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	xstate_comp_offsets[FIRST_EXTENDED_XFEATURE_NR] =
+	  	FXSAVE_SIZE + XSAVE_HDR_SIZE;
 
-	for (i = 2; i < xfeatures_nr; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE_NR; 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_NR)
 			xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
 					+ xstate_comp_sizes[i-1];
 
@@ -305,7 +306,7 @@ static void __init init_xstate_size(void
 	}
 
 	xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
-	for (i = 2; i < 64; i++) {
+	for (i = FIRST_EXTENDED_XFEATURE_NR; i < 64; i++) {
 		if (test_bit(i, (unsigned long *)&xfeatures_mask)) {
 			cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 			xstate_size += eax;
_
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