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Message-ID: <20240628174544.3118826-3-xin@zytor.com>
Date: Fri, 28 Jun 2024 10:45:42 -0700
From: "Xin Li (Intel)" <xin@...or.com>
To: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
will@...nel.org, peterz@...radead.org, akpm@...ux-foundation.org,
acme@...nel.org, namhyung@...nel.org, brgerst@...il.com,
andrew.cooper3@...rix.com, nik.borisov@...e.com
Subject: [PATCH v4 2/4] x86/cpufeatures: Generate a feature mask header based on build config
From: "H. Peter Anvin (Intel)" <hpa@...or.com>
Introduce an AWK script to auto-generate a header with required and
disabled feature masks based on <asm/cpufeatures.h> and current build
config. Thus for any CPU feature with a build config, e.g., X86_FRED,
simply add
config X86_DISABLED_FEATURE_FRED
def_bool y
depends on !X86_FRED
to arch/x86/Kconfig.cpufeatures, instead of adding a conditional CPU
feature disable flag, e.g., DISABLE_FRED.
Lastly the generated required and disabled feature masks will be added
to their corresponding feature masks for this particular compile-time
configuration.
[ Xin: build integration improvements ]
Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
Signed-off-by: Xin Li (Intel) <xin@...or.com>
Reviewed-by: Nikolay Borisov <nik.borisov@...e.com>
---
Changes since v3:
* Add a few high-level comments to the AWK script (Nikolay Borisov).
* Enforce CPU feature mask values to be unsigned.
Changes since v2:
* Remove AWK code that generates extra debugging comments (Brian Gerst).
* Move SSE_MASK to verify_cpu.S, the only place it is used (Brian Gerst).
Change since v1:
* Remove code generating unused macros {REQUIRED,DISABLED}_FEATURE(x)
to tell if a CPU feature, e.g., X86_FEATURE_FRED, is a required or
disabled feature for this particular compile-time configuration.
---
arch/x86/Makefile | 17 +++++-
arch/x86/boot/cpucheck.c | 3 +-
arch/x86/boot/cpuflags.c | 1 -
arch/x86/boot/mkcpustr.c | 3 +-
arch/x86/include/asm/Kbuild | 1 +
arch/x86/include/asm/cpufeature.h | 1 +
arch/x86/include/asm/cpufeatures.h | 8 ---
arch/x86/kernel/verify_cpu.S | 4 ++
arch/x86/tools/featuremasks.awk | 85 ++++++++++++++++++++++++++++++
9 files changed, 109 insertions(+), 14 deletions(-)
create mode 100755 arch/x86/tools/featuremasks.awk
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 801fd85c3ef6..211c0820b150 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -261,9 +261,22 @@ archscripts: scripts_basic
$(Q)$(MAKE) $(build)=arch/x86/tools relocs
###
-# Syscall table generation
+# Feature masks header and syscall table generation
-archheaders:
+out := arch/x86/include/generated/asm
+featuremasks_hdr := featuremasks.h
+featuremasks_awk := $(srctree)/arch/x86/tools/featuremasks.awk
+cpufeatures_hdr := $(srctree)/arch/x86/include/asm/cpufeatures.h
+quiet_cmd_gen_featuremasks = GEN $@
+ cmd_gen_featuremasks = $(AWK) -f $(featuremasks_awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) > $@
+
+$(out)/$(featuremasks_hdr): $(featuremasks_awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) FORCE
+ $(shell mkdir -p $(out))
+ $(call if_changed,gen_featuremasks)
+
+targets += $(out)/$(featuremasks_hdr)
+
+archheaders: $(out)/$(featuremasks_hdr)
$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
###
diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 0aae4d4ed615..8d03a741d1b2 100644
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -22,10 +22,11 @@
# include "boot.h"
#endif
#include <linux/types.h>
+#include <asm/featuremasks.h>
#include <asm/intel-family.h>
#include <asm/processor-flags.h>
-#include <asm/required-features.h>
#include <asm/msr-index.h>
+
#include "string.h"
#include "msr.h"
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c
index d75237ba7ce9..0cabdacb2a2f 100644
--- a/arch/x86/boot/cpuflags.c
+++ b/arch/x86/boot/cpuflags.c
@@ -3,7 +3,6 @@
#include "bitops.h"
#include <asm/processor-flags.h>
-#include <asm/required-features.h>
#include <asm/msr-index.h>
#include "cpuflags.h"
diff --git a/arch/x86/boot/mkcpustr.c b/arch/x86/boot/mkcpustr.c
index da0ccc5de538..b90110109675 100644
--- a/arch/x86/boot/mkcpustr.c
+++ b/arch/x86/boot/mkcpustr.c
@@ -12,8 +12,6 @@
#include <stdio.h>
-#include "../include/asm/required-features.h"
-#include "../include/asm/disabled-features.h"
#include "../include/asm/cpufeatures.h"
#include "../include/asm/vmxfeatures.h"
#include "../kernel/cpu/capflags.c"
@@ -23,6 +21,7 @@ int main(void)
int i, j;
const char *str;
+ printf("#include <asm/featuremasks.h>\n\n");
printf("static const char x86_cap_strs[] =\n");
for (i = 0; i < NCAPINTS; i++) {
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index a192bdea69e2..29c3481f40fc 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -8,6 +8,7 @@ generated-y += syscalls_x32.h
generated-y += unistd_32_ia32.h
generated-y += unistd_64_x32.h
generated-y += xen-hypercalls.h
+generated-y += featuremasks.h
generic-y += early_ioremap.h
generic-y += mcs_spinlock.h
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 0b9611da6c53..8332f596ba3c 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -9,6 +9,7 @@
#include <asm/asm.h>
#include <linux/bitops.h>
#include <asm/alternative.h>
+#include <asm/featuremasks.h>
enum cpuid_leafs
{
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 6007462e03d6..4a297a8a376c 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -2,14 +2,6 @@
#ifndef _ASM_X86_CPUFEATURES_H
#define _ASM_X86_CPUFEATURES_H
-#ifndef _ASM_X86_REQUIRED_FEATURES_H
-#include <asm/required-features.h>
-#endif
-
-#ifndef _ASM_X86_DISABLED_FEATURES_H
-#include <asm/disabled-features.h>
-#endif
-
/*
* Defines x86 CPU feature bits
*/
diff --git a/arch/x86/kernel/verify_cpu.S b/arch/x86/kernel/verify_cpu.S
index 1258a5872d12..a23a65d5d177 100644
--- a/arch/x86/kernel/verify_cpu.S
+++ b/arch/x86/kernel/verify_cpu.S
@@ -29,8 +29,12 @@
*/
#include <asm/cpufeatures.h>
+#include <asm/featuremasks.h>
#include <asm/msr-index.h>
+#define SSE_MASK \
+ (REQUIRED_MASK0 & ((1<<(X86_FEATURE_XMM & 31)) | (1<<(X86_FEATURE_XMM2 & 31))))
+
SYM_FUNC_START_LOCAL(verify_cpu)
pushf # Save caller passed flags
push $0 # Kill any dangerous flags
diff --git a/arch/x86/tools/featuremasks.awk b/arch/x86/tools/featuremasks.awk
new file mode 100755
index 000000000000..351d5a4c7d64
--- /dev/null
+++ b/arch/x86/tools/featuremasks.awk
@@ -0,0 +1,85 @@
+#!/usr/bin/awk
+#
+# Convert cpufeatures.h to a list of compile-time masks
+# Note: this blithly assumes that each word has at least one
+# feature defined in it; if not, something else is wrong!
+#
+
+BEGIN {
+ printf "#ifndef _ASM_X86_FEATUREMASKS_H\n";
+ printf "#define _ASM_X86_FEATUREMASKS_H\n\n";
+
+ file = 0
+}
+
+BEGINFILE {
+ switch (++file) {
+ case 1: # cpufeatures.h
+ FPAT = "#[ \t]*[a-z]+|[A-Za-z0-9_]+|[^ \t]";
+ break;
+ case 2: # .config
+ FPAT = "CONFIG_[A-Z0-9_]+|is not set|[yn]";
+ break;
+ }
+}
+
+# Create a dictionary of sorts, containing all defined feature bits
+file == 1 && $1 ~ /^#[ \t]*define$/ && $2 ~ /^X86_FEATURE_/ &&
+$3 == "(" && $5 == "*" && $7 == "+" && $9 == ")" {
+ nfeat = $4 * $6 + $8;
+ feat = $2;
+ sub(/^X86_FEATURE_/, "", feat);
+ feats[nfeat] = feat;
+}
+file == 1 && $1 ~ /^#[ \t]*define$/ && $2 == "NCAPINTS" {
+ ncapints = strtonum($3);
+}
+
+# Create a dictionary featstat[REQUIRED|DISABLED, FEATURE_NAME] = on | off
+file == 2 && $1 ~ /^CONFIG_X86_[A-Z]*_FEATURE_/ {
+ on = ($2 == "y");
+ if (split($1, fs, "CONFIG_X86_|_FEATURE_") == 3)
+ featstat[fs[2], fs[3]] = on;
+}
+
+END {
+ sets[1] = "REQUIRED";
+ sets[2] = "DISABLED";
+
+ for (ns in sets) {
+ s = sets[ns];
+
+ printf "/*\n";
+ printf " * %s features:\n", s;
+ printf " *\n";
+ fstr = "";
+ for (i = 0; i < ncapints; i++) {
+ mask = 0;
+ for (j = 0; j < 32; j++) {
+ nfeat = i*32 + j;
+ feat = feats[nfeat];
+ if (feat) {
+ st = !!featstat[s, feat];
+ if (st) {
+ nfstr = fstr " " feat;
+ if (length(nfstr) > 72) {
+ printf " * %s\n", fstr;
+ nfstr = " " feat;
+ }
+ fstr = nfstr;
+ mask += (2 ^ j);
+ }
+ }
+ }
+ masks[i] = mask;
+ }
+ printf " * %s\n */\n", fstr;
+
+ for (i = 0; i < ncapints; i++)
+ printf "#define %s_MASK%d\t0x%08xU\n", s, i, masks[i];
+
+ printf "#define %s_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != %d)\n\n", s, ncapints;
+ }
+
+ printf "#endif /* _ASM_X86_FEATUREMASKS_H */\n";
+}
--
2.45.2
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