scripts: get_abi.pl: fix parse logic for DT firmware

It doesn't make any sense to parse ABI entries under
/sys/firmware, as those are either specified by ACPI specs
or by Documentation/devicetree.

The current logic to ignore firmware entries is incomplete,
as it ignores just the relative name of the file, and not
its absolute name. This cause errors while parsing the
symlinks.

So, rewrite the logic for it to do a better job.

Tested with both x86 and arm64 (HiKey970) systems.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/1c806eaec96f6706db4b041bbe6a0e2519e9637e.1632750315.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

scripts/get_abi.pl

@@ -635,19 +635,29 @@ my $escape_symbols = qr { ([\x01-\x08\x0e-\x1f\x21-\x29\x2b-\x2d\x3a-\x40\x7b-\x
 sub parse_existing_sysfs {
 	my $file = $File::Find::name;
 
-	# Ignore cgroup and firmware
-	return if ($file =~ m#^/sys/(fs/cgroup|firmware)/#);
+	my $mode = (lstat($file))[2];
+	my $abs_file = abs_path($file);
 
-	# Ignore some sysfs nodes
-	return if ($file =~ m#/(sections|notes)/#);
+	my @tmp;
+	push @tmp, $file;
+	push @tmp, $abs_file if ($abs_file ne $file);
 
-	# Would need to check at
-	# Documentation/admin-guide/kernel-parameters.txt, but this
-	# is not easily parseable.
-	return if ($file =~ m#/parameters/#);
+	foreach my $f(@tmp) {
+		# Ignore cgroup, as this is big and has zero docs under ABI
+		return if ($f =~ m#^/sys/fs/cgroup/#);
 
-	my $mode = (lstat($file))[2];
-	my $abs_file = abs_path($file);
+		# Ignore firmware as it is documented elsewhere
+		# Either ACPI or under Documentation/devicetree/bindings/
+		return if ($f =~ m#^/sys/firmware/#);
+
+		# Ignore some sysfs nodes that aren't actually part of ABI
+		return if ($f =~ m#/sections|notes/#);
+
+		# Would need to check at
+		# Documentation/admin-guide/kernel-parameters.txt, but this
+		# is not easily parseable.
+		return if ($f =~ m#/parameters/#);
+	}
 
 	if (S_ISLNK($mode)) {
 		$aliases{$file} = $abs_file;