SIGILL in detect_arm_hwf_by_toolchain under FreeBSD arm64 on a Raspberry Pi 4B

[Naram Qashat]

I don't know if this started to happen after I updated to FreeBSD 14.1 
on my RPi4B, but libgcrypt crashes with a SIGILL in 
detect_arm_hwf_by_toolchain on line 527 when trying to run the assembly 
code there. As a result, I cannot use gnupg either. I asked about this 
in one of the FreeBSD IRC channels and this was the conversation about 
it:

[07/09/2024 10:33:10 -4] <CBX-AWAY> So I build all my packages for my 
RPi4 via poudriere with CPUTYPE set to cortex-a72, and now for some 
reason, gpg2 crashes in libgcrypt when trying to run the asm to detect 
CPU features, specifically with a SIGILL: illegal trap. Specifically it 
crashes at this line: 
https://fossies.org/dox/libgcrypt-1.11.0/hwf-arm_8c_source.html#l00527
[07/09/2024 10:35:01 -4] <@fuz> ouch
[07/09/2024 10:35:25 -4] <@fuz> CBX-AWAY: that's a crypto instruction, 
they're optional on the A72 and the rpi4 doesn't have them
[07/09/2024 10:36:37 -4] <CBX-AWAY> That is an ouch indeed. Now I wonder 
what I can do about it, if there is even anything I can do about it.
[07/09/2024 10:37:33 -4] <@fuz> not sure
[07/09/2024 10:42:05 -4] <jhibbits> Is there a compiler flag to disable 
crypto?
[07/09/2024 10:42:29 -4] <@fuz> jhibbits: by default it's not enabled
[07/09/2024 10:42:37 -4] <@fuz> you have to add +crypto to enable it
[07/09/2024 10:42:40 -4] <jhibbits> ah
[07/09/2024 10:43:26 -4] <jhibbits> So libgcrypt assumes that it's 
enabled, or tries to use a SIGILL handler to confirm?
[07/09/2024 10:44:15 -4] <@fuz> the code linked looks like it exercises 
the assembler
[07/09/2024 10:44:22 -4] <@fuz> to check if the mnemonics are supported
[07/09/2024 10:44:54 -4] <jhibbits> That code is all sorts of wrong
[07/09/2024 10:56:42 -4] <jhibbits> OR-ing in all options supported by 
the compiler, whether supported by the hardware or not, is very wrong.
[07/09/2024 10:57:33 -4] <jhibbits> CBX-AWAY: you should file a bug with 
libgcrypt to fix that brokenness
[07/09/2024 10:57:38 -4] <@fuz> jhibbits: if you build for a 
distribution, it makes sense to build a binary that can use all features 
the compiler supports, so you can select at runtime what you need.
[07/09/2024 10:58:15 -4] <jhibbits> fuz: yes, but this is a runtime file
[07/09/2024 10:59:33 -4] <jhibbits> fuz: it's explicitly ORing in all 
compiler-supported features, whether supported by the hardware (via 
HW_CAP or /proc/cpuinfo, or sysctl).
[07/09/2024 10:59:42 -4] <jhibbits> It should be taking a subset of 
those.
[07/09/2024 11:03:19 -4] <@fuz> ok that's weird
[07/09/2024 11:03:26 -4] <@fuz> though on freebsd we only support HW_CAP
[07/09/2024 11:03:35 -4] <@fuz> and reading the special registers 
directly
[07/09/2024 11:03:46 -4] <@fuz> so idk what other data sources there are
[07/09/2024 11:04:07 -4] <jhibbits> That's all that should be needed
[07/09/2024 11:04:48 -4] <jhibbits> That detect_arm_hwf_by_toolchain() 
is severely broken, and shouldn't exist.

I'm not sure what the actual fix is for this, and I cannot post this to 
the GnuPG issue tracker as I don't have an account and registration 
there is disabled. If it would be better for me to post this on the 
issue tracker, then for my account, I'd like the handle CyberBotX, my 
shown name as Naram Qashat, and my email address as 
cyberbotx at cyberbotx.com.

Thanks in advance,
Naram "CyberBotX" Qashat