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Subject[tip:x86/urgent] x86, cpufeature: Catch duplicate CPU feature strings
Commit-ID:  55f6cb9d0b364e7e8cb65b51193f5e4743c44fde
Gitweb: http://git.kernel.org/tip/55f6cb9d0b364e7e8cb65b51193f5e4743c44fde
Author: H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Fri, 22 Jun 2012 11:47:15 -0700
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Mon, 25 Jun 2012 09:02:13 -0700

x86, cpufeature: Catch duplicate CPU feature strings

We had a case of duplicate CPU feature strings, a user space ABI
violation, for almost two years. Make it a build error so that
doesn't happen again.

Link: http://lkml.kernel.org/r/4FE34BCB.5050305@linux.intel.com
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Jean Delvare <khali@linux-fr.org>
---
arch/x86/kernel/cpu/mkcapflags.pl | 23 ++++++++++++++++++-----
1 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/mkcapflags.pl b/arch/x86/kernel/cpu/mkcapflags.pl
index dfea390..0c5b549 100644
--- a/arch/x86/kernel/cpu/mkcapflags.pl
+++ b/arch/x86/kernel/cpu/mkcapflags.pl
@@ -11,22 +11,35 @@ open(OUT, "> $out\0") or die "$0: cannot create: $out: $!\n";
print OUT "#include <asm/cpufeature.h>\n\n";
print OUT "const char * const x86_cap_flags[NCAPINTS*32] = {\n";

+%features = ();
+$err = 0;
+
while (defined($line = <IN>)) {
if ($line =~ /^\s*\#\s*define\s+(X86_FEATURE_(\S+))\s+(.*)$/) {
$macro = $1;
- $feature = $2;
+ $feature = "\L$2";
$tail = $3;
if ($tail =~ /\/\*\s*\"([^"]*)\".*\*\//) {
- $feature = $1;
+ $feature = "\L$1";
}

- if ($feature ne '') {
- printf OUT "\t%-32s = \"%s\",\n",
- "[$macro]", "\L$feature";
+ next if ($feature eq '');
+
+ if ($features{$feature}++) {
+ print STDERR "$in: duplicate feature name: $feature\n";
+ $err++;
}
+ printf OUT "\t%-32s = \"%s\",%s\n", "[$macro]", $feature;
}
}
print OUT "};\n";

close(IN);
close(OUT);
+
+if ($err) {
+ unlink($out);
+ exit(1);
+}
+
+exit(0);

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