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@zytor.com>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250305184725.3341760-3-xin@zytor.com

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 6784129328f6a96fe4661674130eb349fe02c02d..a607769a25afdf282abc68f15154457ccf907c52 100644 (file)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -268,6 +268,21 @@ archscripts: scripts_basic
 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
 

diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 0aae4d4ed61502efe2113f7564176df25260eb95..f82de8de5dc62ea8a7f76f011d2de3cea1f9f234 100644 (file)
--- 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 d75237ba7ce94415de457a38d41c38df69c0c8a7..0cabdacb2a2fc2e07a135e4710b06c79f2187d24 100644 (file)
--- 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 da0ccc5de538064f5a3bf767d9dd8918e6562f38..22d730b227e385347bcc69b0b853fd78c6974be4 100644 (file)
--- 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 58f4ddecc5fa2888236d0405cfe1d8cc53d550d1..4566000e15c446fbb971db0ae3df68b959e8814a 100644 (file)
--- 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 e955da397e0e207be83fe4425ffaed0177c35deb..d54db88fae93b239e53496662e031db034decfd2 100644 (file)
--- 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 8770dc185fe91e026b1a19ff4a809ad43e6f844a..c0462be0c5f60e951d28fbe3f2c4ca3959f08cac 100644 (file)
--- 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 1258a5872d128362530084f54c3ec09dfb46f0e1..37ad43792452323bfd656981c56dd83649159e94 100644 (file)
--- 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 (executable)
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";
+}