Re: [PATCH 0/2] *** Fix reformat_objdump.awk ***

From: Nathan Chancellor <nathan@kernel.org>
To: Samuel Zeter <samuelzeter@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 0/2] *** Fix reformat_objdump.awk ***
Date: Thu, 6 Jan 2022 12:02:25 -0700	[thread overview]
Message-ID: <Ydc8wUjX4hnHg7ZE@archlinux-ax161> (raw)
In-Reply-To: <20220106023606.283953-1-samuelzeter@gmail.com>

On Thu, Jan 06, 2022 at 01:36:03PM +1100, Samuel Zeter wrote:
> These are two small patches which originally dealt with
> the problem found at:
> 
> https://github.com/ClangBuiltLinux/linux/issues/1364
> 
> The original steps to reproduce were:
> $ make -skj"$(nproc)" LLVM=1 LLVM_IAS=1 defconfig
> $ scripts/config -e X86_DECODER_SELFTEST
> $ make -skj"$(nproc)" LLVM=1 LLVM_IAS=1 olddefconfig bzImage
> 
> Which resulted in the error:
> arch/x86/tools/insn_decoder_test: warning: objdump says 0 bytes, but
> insn_get_length() says 2
> 
> Upon inspection it turned out llvm-objdump was formatting its
> output differently, which caused objdump_reformat.awk to incorrectly
> output its values.
> 
> After fixing that bug, a second one was seen where the instruction
> "wait" was incorrectly matched with "fwait", which again caused
> insn_decoder_test to fail.

Thanks a lot for sending these fixes!

I can confirm with this series and the removal of chkobjdump.awk [1] on
top of v5.16-rc8, the insn_decoder_test now passes with LLVM 11 through
14.

Tested-by: Nathan Chancellor <nathan@kernel.org>

For the future, I recommend putting the maintainers in the "To" field,
rather than "Cc", to ensure they actually see it. Additionally, I see
some small nits in the commit message that the tip maintainers might
comment on, see

https://www.kernel.org/doc/html/latest/process/maintainer-tip.html#changelog

for some more info.

Masami Hiramatsu originally wrote this file and has a few fixes to it
since, adding him now for review. The original thread is available at:

https://lore.kernel.org/r/20220106023606.283953-1-samuelzeter@gmail.com/

[1]: https://git.kernel.org/nathan/c/2f137c324b21f1c21b8830d8896cb9957009f969

Cheers,
Nathan