From: Eric Biggers <ebiggers@kernel.org>
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
keescook@chromium.org, linux-hardening@vger.kernel.org,
nathan@kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Jan Beulich <jbeulich@suse.com>,
"Jose E. Marchesi" <jemarch@gnu.org>, Kees Cook <kees@kernel.org>
Subject: Re: [PATCH v3 6/8] crypto: x86/crc32c - Use idiomatic relative jump table
Date: Sun, 13 Oct 2024 21:28:33 -0700 [thread overview]
Message-ID: <20241014042833.GA20015@sol.localdomain> (raw)
In-Reply-To: <20241011170847.334429-16-ardb+git@google.com>
On Fri, Oct 11, 2024 at 07:08:54PM +0200, Ard Biesheuvel wrote:
> diff --git a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
> index bbcff1fb78cb..45b005935194 100644
> --- a/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
> +++ b/arch/x86/crypto/crc32c-pcl-intel-asm_64.S
> @@ -53,7 +53,7 @@
> .endm
>
> .macro JMPTBL_ENTRY i
> -.quad .Lcrc_\i
> +.long .Lcrc_\i - jump_table
> .endm
>
> .macro JNC_LESS_THAN j
> @@ -169,7 +169,8 @@ SYM_FUNC_START(crc_pcl)
>
> ## branch into array
> leaq jump_table(%rip), %bufp
> - mov (%bufp,%rax,8), %bufp
> + movslq (%bufp,%rax,4), len
> + addq len, %bufp
> JMP_NOSPEC bufp
I think it would be much better to just get rid of the jump table here.
I have done this at
https://lore.kernel.org/linux-crypto/20241014042447.50197-4-ebiggers@kernel.org/
- Eric
next prev parent reply other threads:[~2024-10-14 4:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-11 17:08 [PATCH v3 0/8] Improve objtool jump table handling Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 1/8] objtool: Deal with relative jump tables correctly Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 2/8] objtool: Allow arch code to discover jump table size Ard Biesheuvel
2024-12-03 10:45 ` [tip: objtool/core] " tip-bot2 for Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 3/8] objtool: Make some helper functions globally accessible Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 4/8] objtool: Move jump table heuristics to a x86 specific source file Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 5/8] objtool: Add generic support for jump table annotations Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 6/8] crypto: x86/crc32c - Use idiomatic relative jump table Ard Biesheuvel
2024-10-14 4:28 ` Eric Biggers [this message]
2024-10-14 9:36 ` Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 7/8] crypto: x86/crc32c - Add jump table annotation Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 8/8] crypto: x86/crc32c-intel - Tweaks to make objtool's life harder Ard Biesheuvel
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