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Date:   Fri, 18 Nov 2022 14:33:11 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     x86@kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-crypto@vger.kernel.org
Subject: Re: [PATCH v2 08/12] crypto: x86/sm4 - fix crash with CFI enabled
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On Fri, Nov 18, 2022 at 02:01:40PM -0800, Sami Tolvanen wrote:
> On Fri, Nov 18, 2022 at 12:53 PM Sami Tolvanen <samitolvanen@google.com> wrote:
> >
> > On Fri, Nov 18, 2022 at 12:27 PM Sami Tolvanen <samitolvanen@google.com> wrote:
> > >
> > > On Fri, Nov 18, 2022 at 12:10 PM Eric Biggers <ebiggers@kernel.org> wrote:
> > > > 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.
> > >
> > > If the compiler emits an indirect call, it should also emit a CFI
> > > check. What's the assembly code it generates here?
> >
> > With CONFIG_RETPOLINE, the check is emitted as expected, but I can
> > reproduce this issue without retpolines. It looks like the cfi-type
> > attribute is dropped from the machine instruction in one of the X86
> > specific passes. I'll take a look.
> 
> This should now be fixed in ToT LLVM after commit 7c96f61aaa4c. Thanks
> for spotting the issue!
> 

Thanks, it seems to work now.  (If I revert my sm4 fix, I get a CFI failure as
expected.)

- Eric