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Message-ID: <20251112160315.2207947-25-alexandre.chartre@oracle.com>
Date: Wed, 12 Nov 2025 17:03:11 +0100
From: Alexandre Chartre <alexandre.chartre@...cle.com>
To: linux-kernel@...r.kernel.org, mingo@...nel.org, jpoimboe@...nel.org,
peterz@...radead.org
Cc: alexandre.chartre@...cle.com
Subject: [PATCH v3 24/28] objtool: Function to get the name of a CPU feature
Add a function to get the name of a CPU feature. The function is
architecture dependent and currently only implemented for x86. The
feature names are automatically generated from the cpufeatures.h
include file.
Signed-off-by: Alexandre Chartre <alexandre.chartre@...cle.com>
---
.../x86/tools/gen-cpu-feature-names-x86.awk | 33 +++++++++++++++++++
tools/objtool/Makefile | 1 +
tools/objtool/arch/loongarch/special.c | 5 +++
tools/objtool/arch/powerpc/special.c | 5 +++
tools/objtool/arch/x86/Build | 8 +++++
tools/objtool/arch/x86/special.c | 10 ++++++
tools/objtool/include/objtool/special.h | 2 ++
7 files changed, 64 insertions(+)
create mode 100644 tools/arch/x86/tools/gen-cpu-feature-names-x86.awk
diff --git a/tools/arch/x86/tools/gen-cpu-feature-names-x86.awk b/tools/arch/x86/tools/gen-cpu-feature-names-x86.awk
new file mode 100644
index 0000000000000..1b1c1d84225c2
--- /dev/null
+++ b/tools/arch/x86/tools/gen-cpu-feature-names-x86.awk
@@ -0,0 +1,33 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2025, Oracle and/or its affiliates.
+#
+# Usage: awk -f gen-cpu-feature-names-x86.awk cpufeatures.h > cpu-feature-names.c
+#
+
+BEGIN {
+ print "/* cpu feature name array generated from cpufeatures.h */"
+ print "/* Do not change this code. */"
+ print
+ print "static const char *cpu_feature_names[(NCAPINTS+NBUGINTS)*32] = {"
+
+ feature_expr = "(X86_FEATURE_[A-Z0-9_]+)\\s+\\(([0-9*+ ]+)\\)"
+ debug_expr = "(X86_BUG_[A-Z0-9_]+)\\s+X86_BUG\\(([0-9*+ ]+)\\)"
+}
+
+/^#define X86_FEATURE_/ {
+ if (match($0, feature_expr, m)) {
+ print "\t[" m[2] "] = \"" m[1] "\","
+ }
+}
+
+/^#define X86_BUG_/ {
+ if (match($0, debug_expr, m)) {
+ print "\t[NCAPINTS*32+(" m[2] ")] = \"" m[1] "\","
+ }
+}
+
+END {
+ print "};"
+}
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 9fb83979ca890..b6df180121589 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -109,6 +109,7 @@ clean: $(LIBSUBCMD)-clean
$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep
+ $(Q)$(RM) $(OUTPUT)arch/x86/lib/cpu-feature-names.c $(OUTPUT)fixdep
FORCE:
diff --git a/tools/objtool/arch/loongarch/special.c b/tools/objtool/arch/loongarch/special.c
index a80b75f7b061f..aba774109437f 100644
--- a/tools/objtool/arch/loongarch/special.c
+++ b/tools/objtool/arch/loongarch/special.c
@@ -194,3 +194,8 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
return rodata_reloc;
}
+
+const char *arch_cpu_feature_name(int feature_number)
+{
+ return NULL;
+}
diff --git a/tools/objtool/arch/powerpc/special.c b/tools/objtool/arch/powerpc/special.c
index 51610689abf72..8f9bf61ca0899 100644
--- a/tools/objtool/arch/powerpc/special.c
+++ b/tools/objtool/arch/powerpc/special.c
@@ -18,3 +18,8 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
{
exit(-1);
}
+
+const char *arch_cpu_feature_name(int feature_number)
+{
+ return NULL;
+}
diff --git a/tools/objtool/arch/x86/Build b/tools/objtool/arch/x86/Build
index 3dedb2fd8f3a0..1067355361b56 100644
--- a/tools/objtool/arch/x86/Build
+++ b/tools/objtool/arch/x86/Build
@@ -11,4 +11,12 @@ $(OUTPUT)arch/x86/lib/inat-tables.c: $(inat_tables_script) $(inat_tables_maps)
$(OUTPUT)arch/x86/decode.o: $(OUTPUT)arch/x86/lib/inat-tables.c
+cpu_features = ../arch/x86/include/asm/cpufeatures.h
+cpu_features_script = ../arch/x86/tools/gen-cpu-feature-names-x86.awk
+
+$(OUTPUT)arch/x86/lib/cpu-feature-names.c: $(cpu_features_script) $(cpu_features)
+ $(Q)$(call echo-cmd,gen)$(AWK) -f $(cpu_features_script) $(cpu_features) > $@
+
+$(OUTPUT)arch/x86/special.o: $(OUTPUT)arch/x86/lib/cpu-feature-names.c
+
CFLAGS_decode.o += -I$(OUTPUT)arch/x86/lib
diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 06ca4a2659a45..720127fd4d025 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -4,6 +4,10 @@
#include <objtool/special.h>
#include <objtool/builtin.h>
#include <objtool/warn.h>
+#include <asm/cpufeatures.h>
+
+/* cpu feature name array generated from cpufeatures.h */
+#include "lib/cpu-feature-names.c"
void arch_handle_alternative(struct special_alt *alt)
{
@@ -134,3 +138,9 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
*table_size = 0;
return rodata_reloc;
}
+
+const char *arch_cpu_feature_name(int feature_number)
+{
+ return (feature_number < ARRAY_SIZE(cpu_feature_names)) ?
+ cpu_feature_names[feature_number] : NULL;
+}
diff --git a/tools/objtool/include/objtool/special.h b/tools/objtool/include/objtool/special.h
index b22410745e4a1..121c3761899c1 100644
--- a/tools/objtool/include/objtool/special.h
+++ b/tools/objtool/include/objtool/special.h
@@ -38,4 +38,6 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
struct reloc *arch_find_switch_table(struct objtool_file *file,
struct instruction *insn,
unsigned long *table_size);
+const char *arch_cpu_feature_name(int feature_number);
+
#endif /* _SPECIAL_H */
--
2.43.5
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