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Date:   Fri, 11 Feb 2022 16:37:06 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alexander Lobakin <alexandr.lobakin@intel.com>
Cc:     linux-hardening@vger.kernel.org, x86@kernel.org,
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Subject: Re: [PATCH v10 10/15] FG-KASLR: use a scripted approach to handle
 .text.* sections
Message-ID: <20220211153706.GW23216@worktop.programming.kicks-ass.net>
References: <20220209185752.1226407-1-alexandr.lobakin@intel.com>
 <20220209185752.1226407-11-alexandr.lobakin@intel.com>
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On Wed, Feb 09, 2022 at 07:57:47PM +0100, Alexander Lobakin wrote:
> +sub read_sections {
> +	open(my $fh, "\"$readelf\" -SW \"$file\" 2>/dev/null |")
> +		or die "$0: ERROR: failed to execute \"$readelf\": $!";
> +
> +	while (<$fh>) {
> +		my $name;
> +		my $align;
> +		chomp;
> +
> +		($name, $align) = $_ =~ /^\s*\[[\s0-9]*\]\s*(\.\S*)\s*[A-Z]*\s*[0-9a-f]{16}\s*[0-9a-f]*\s*[0-9a-f]*\s*[0-9a-f]*\s*[0-9a-f]{2}\s*[A-Z]{2}\s*[0-9]\s*[0-9]\s*([0-9]*)$/;

Is there really no readable way to write this?

> +
> +		if (!defined($name)) {
> +			next;
> +		}
> +
> +		## Clang 13 onwards emits __cfi_check_fail only on final
> +		## linking, so it won't appear in .o files and will be
> +		## missing in @sections. Add it manually to prevent
> +		## spawning orphans.
> +		if ($name eq ".text.__cfi_check_fail") {
> +			$has_ccf = 1;
> +		}

How is that relevant, x86-64 doesn't and won't do clang-cfi.