[PATCH v2 08/12] crypto: x86/sm4 - fix crash with CFI enabled

[Eric Biggers]

On Fri, Nov 18, 2022 at 11:44:17AM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers at google.com>
> 
> sm4_aesni_avx_ctr_enc_blk8(), sm4_aesni_avx_cbc_dec_blk8(),
> sm4_aesni_avx_cfb_dec_blk8(), sm4_aesni_avx2_ctr_enc_blk16(),
> sm4_aesni_avx2_cbc_dec_blk16(), and sm4_aesni_avx2_cfb_dec_blk16() are
> called via indirect function calls.  Therefore they need to use
> SYM_TYPED_FUNC_START instead of SYM_FUNC_START to cause their type
> hashes to be emitted when the kernel is built with CONFIG_CFI_CLANG=y.
> Otherwise, the code crashes with a CFI failure.
> 
> (Or at least that should be the case.  For some reason the CFI checks in
> sm4_avx_cbc_decrypt(), sm4_avx_cfb_decrypt(), and sm4_avx_ctr_crypt()
> are not always being generated, using current tip-of-tree clang.
> Anyway, this patch is a good idea anyway.)

Sami, is it expected that a CFI check isn't being generated for the indirect
call to 'func' in sm4_avx_cbc_decrypt()?  I'm using LLVM commit 4a7be42d922af0.

- Eric