From: Arnd Bergmann <arnd@arndb.de>
To: James Morris <jmorris@redhat.com>
Subject: Re: [CRYPTO]: Miscompiling sha256.c by gcc 3.2.3 and arch pentium3,4
Date: Fri, 30 Jan 2004 16:43:13 +0100
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James Morris wrote:
> Have you noticed if this happens for any of the other crypto algorithms?

Just as a reminder, there is still an issue with extreme stack usage
of some of the algorithms, depending on compiler version and
flags.

The worst I have seen was around 16kb for twofish_setkey on 64 bit
s390 with gcc-3.1 (iirc). Right now, I get up to 4kb for this
function with gcc-3.3.1, which probably works but is definitely
a bad sign. I've seen this as well on other architectures (iirc
on x86_64), but not as severe.

Other algorithms are bad as well, these are the top scores from
J?rn Engel's checkstack.pl (s390 64bit 2.6.1 gcc-3.3.1):

0x00000a twofish_setkey:           lay    %r15,-3960(%r15)
0x0026fc aes_decrypt:              lay    %r15,-1168(%r15)
0x000c0c aes_encrypt:              lay    %r15,-1000(%r15)
0x00000e sha512_transform:         lay    %r15,-936(%r15)
0x001292 test_deflate:             lay    %r15,-784(%r15)
0x0028a2 cast6_decrypt:            lay    %r15,-696(%r15)
0x00d1a0 twofish_encrypt:          lay    %r15,-664(%r15)
0x001b34 setkey:                   lay    %r15,-656(%r15)
0x00e2b0 twofish_decrypt:          lay    %r15,-624(%r15)
0x000c9e cast6_encrypt:            lay    %r15,-600(%r15)
0x000014 sha1_transform:           lay    %r15,-504(%r15)
                                                 ^
		This is the stack size   --------|

       Arnd <><

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