linux-kernel - Re: [PATCH 00/13] x86/crypto/asm: objtool support

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Date:   Thu, 25 Feb 2021 07:29:40 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, Herbert Xu <herbert@...dor.apana.org.au>,
        linux-kernel@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>,
        Eric Biggers <ebiggers@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-crypto@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH 00/13] x86/crypto/asm: objtool support

On Thu, Feb 25, 2021 at 10:46:56AM +0100, Peter Zijlstra wrote:
> On Wed, Feb 24, 2021 at 10:29:13AM -0600, Josh Poimboeuf wrote:
> > Standardize the crypto asm to make it resemble compiler-generated code,
> > so that objtool can understand it.
> > 
> > This magically enables ORC unwinding from crypto code.  It also fixes
> > the last known remaining objtool warnings on vmlinux.o, for LTO and
> > more.
> > 
> > Josh Poimboeuf (13):
> >   objtool: Support asm jump tables
> >   x86/crypto/aesni-intel_avx: Remove unused macros
> >   x86/crypto/aesni-intel_avx: Fix register usage comments
> >   x86/crypto/aesni-intel_avx: Standardize stack alignment prologue
> >   x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer
> >   x86/crypto/crc32c-pcl-intel: Standardize jump table
> >   x86/crypto/sha_ni: Standardize stack alignment prologue
> >   x86/crypto/sha1_avx2: Standardize stack alignment prologue
> >   x86/crypto/sha256-avx2: Standardize stack alignment prologue
> >   x86/crypto/sha512-avx: Standardize stack alignment prologue
> >   x86/crypto/sha512-avx2: Standardize stack alignment prologue
> >   x86/crypto/sha512-ssse3: Standardize stack alignment prologue
> >   x86/crypto: Enable objtool in crypto code
> > 
> >  arch/x86/crypto/Makefile                     |  2 -
> >  arch/x86/crypto/aesni-intel_avx-x86_64.S     | 28 +++++--------
> >  arch/x86/crypto/camellia-aesni-avx2-asm_64.S |  5 +--
> >  arch/x86/crypto/crc32c-pcl-intel-asm_64.S    |  7 +---
> >  arch/x86/crypto/sha1_avx2_x86_64_asm.S       |  8 ++--
> >  arch/x86/crypto/sha1_ni_asm.S                |  8 ++--
> >  arch/x86/crypto/sha256-avx2-asm.S            | 13 +++---
> >  arch/x86/crypto/sha512-avx-asm.S             | 41 +++++++++----------
> >  arch/x86/crypto/sha512-avx2-asm.S            | 42 ++++++++++----------
> >  arch/x86/crypto/sha512-ssse3-asm.S           | 41 +++++++++----------
> >  tools/objtool/check.c                        | 14 ++++++-
> >  11 files changed, 98 insertions(+), 111 deletions(-)
> 
> One nit, there's lots and lots of:
> 
> 	mov %rbp, %rsp
> 	pop %rbp
> 
> and we have this 'leave' instruction that does exactly that, should we
> be using it?

I'd considered that, but LEAVE is more cryptic (no pun intended).  This
code often has "surprises", so I prefer the readability of the more
explicit instructions.

> Otherwise:
> 
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Thanks.

-- 
Josh