The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: 7a7bd24a0ca02dfe68bd8a7a567b3da3b716bd8d
Gitweb: https://git.kernel.org/tip/7a7bd24a0ca02dfe68bd8a7a567b3da3b716bd8d
Author: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
AuthorDate: Wed, 05 Mar 2025 10:47:22 -08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 10 Mar 2025 09:02:47 +01:00
x86/cpufeatures: Generate the <asm/cpufeaturemasks.h> header based on build config
Introduce an AWK script to auto-generate the <asm/cpufeaturemasks.h> header
with required and disabled feature masks based on <asm/cpufeatures.h>
and the 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 ]
[ mingo: Improved changelog and comments ]
Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250305184725.3341760-3-xin@xxxxxxxxx
---
arch/x86/Makefile | 15 +++++-
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/cpufeaturemasks.awk | 81 +++++++++++++++++++++++++++++-
9 files changed, 105 insertions(+), 12 deletions(-)
create mode 100755 arch/x86/tools/cpufeaturemasks.awk
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 8120085..420f086 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -265,6 +265,21 @@ archheaders:
$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
###
+# <asm/cpufeaturemasks.h> header generation
+
+cpufeaturemasks.hdr := arch/x86/include/generated/asm/cpufeaturemasks.h
+cpufeaturemasks.awk := $(srctree)/arch/x86/tools/cpufeaturemasks.awk
+cpufeatures_hdr := $(srctree)/arch/x86/include/asm/cpufeatures.h
+targets += $(cpufeaturemasks.hdr)
+quiet_cmd_gen_featuremasks = GEN $@
+ cmd_gen_featuremasks = $(AWK) -f $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) > $@
+
+$(cpufeaturemasks.hdr): $(cpufeaturemasks.awk) $(cpufeatures_hdr) $(KCONFIG_CONFIG) FORCE
+ $(shell mkdir -p $(dir $@))
+ $(call if_changed,gen_featuremasks)
+archprepare: $(cpufeaturemasks.hdr)
+
+###
# Kernel objects
libs-y += arch/x86/lib/
diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 0aae4d4..f82de8d 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/cpufeaturemasks.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 d75237b..0cabdac 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 da0ccc5..22d730b 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/cpufeaturemasks.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 58f4dde..4566000 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 += cpufeaturemasks.h
generic-y += early_ioremap.h
generic-y += fprobe.h
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index e955da3..d54db88 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/cpufeaturemasks.h>
enum cpuid_leafs
{
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 8770dc1..c0462be 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 1258a58..37ad437 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/cpufeaturemasks.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/cpufeaturemasks.awk b/arch/x86/tools/cpufeaturemasks.awk
new file mode 100755
index 0000000..59757ca
--- /dev/null
+++ b/arch/x86/tools/cpufeaturemasks.awk
@@ -0,0 +1,81 @@
+#!/usr/bin/awk
+#
+# Convert cpufeatures.h to a list of compile-time masks
+# Note: this blithely assumes that each word has at least one
+# feature defined in it; if not, something else is wrong!
+#
+
+BEGIN {
+ printf "#ifndef _ASM_X86_CPUFEATUREMASKS_H\n";
+ printf "#define _ASM_X86_CPUFEATUREMASKS_H\n\n";
+
+ file = 0
+}
+
+FNR == 1 {
+ ++file;
+
+ # arch/x86/include/asm/cpufeatures.h
+ if (file == 1)
+ FS = "[ \t()*+]+";
+
+ # .config
+ if (file == 2)
+ FS = "=";
+}
+
+# Create a dictionary of sorts, containing all defined feature bits
+file == 1 && $1 ~ /^#define$/ && $2 ~ /^X86_FEATURE_/ {
+ nfeat = $3 * $4 + $5;
+ feat = $2;
+ sub(/^X86_FEATURE_/, "", feat);
+ feats[nfeat] = feat;
+}
+file == 1 && $1 ~ /^#define$/ && $2 == "NCAPINTS" {
+ ncapints = int($3);
+}
+
+# Create a dictionary featstat[REQUIRED|DISABLED, FEATURE_NAME] = on | off
+file == 2 && $1 ~ /^CONFIG_X86_(REQUIRED|DISABLED)_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++) {
+ feat = feats[i*32 + j];
+ if (featstat[s, feat]) {
+ 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_CPUFEATUREMASKS_H */\n";
+}
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