Thanks. Test works in my nightly builds now.

Do you have any way to test PAC/BTI on actual HW that support these extensions?

This excludes 32-bit ARM assembly from Aarch64 builds:

Here's patch:

This patch should fix the issue:

Ok, so aarch64 assembly would need PAC and BTI support. As far as I have understood these, is that PAC instructions are not needed with current assembly as none of those is storing/loading LR register (all aarch64 assembly functions are leaf functions). So only BTI is needed and that is basically same modification as CET on x86.

"rijndael-vaes-avx2-i386.S" should not be build for x86-64 but until now that has not had any affect as #ifdefs in that source file result empty object file on x86-64.

Here's patches for adding CET support to x86-64 and i386 assembly.

OpenBSD carries libgcrypt patch for CET which adds endbr64 instruction to CFI_STARTPROC() macro in "asm-common-amd64.h". We could do the same and also add endbr32 to i386 too. That would be easiest way to add required endbr instructions. OpenBSD also has patch for arm64 to add similar BTI instructions to aarch64 variant of CFI_STARTPROC.

There is -O flag munging for "tiger.o" in "cipher/Makefile.am", an old workaround for broken compiler I think. IMHO tiger.o case can and should be removed.

OpenBSD carries libgcrypt patch for CET which adds endbr64 instruction to CFI_STARTPROC() macro in "asm-common-amd64.h". We could do the same and also add endbr32 to i386 too. That would be easiest way to add required endbr instructions. OpenBSD also has patch for arm64 to add similar BTI instructions to aarch64 variant of CFI_STARTPROC.

I tried to reproduce issue with clang/w32 toolchain from https://github.com/mstorsjo/llvm-mingw but there build worked even with CFI directives.

Hm, CFI directives should not be used on WIN32 target. This patch should solve the issue for now: