From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Julien <julien.thierry.kdev@gmail.com>
Cc: raph.gault+kdev@gmail.com, peterz@infradead.org,
catalin.marinas@arm.com, will.deacon@arm.com,
linux-kernel@vger.kernel.org,
Raphael Gault <raphael.gault@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC v4 07/18] objtool: Introduce INSN_UNKNOWN type
Date: Thu, 22 Aug 2019 16:51:12 -0500 [thread overview]
Message-ID: <20190822215112.n36slswph64nbzhb@treble> (raw)
In-Reply-To: <3c4e3227-eeb3-371a-d015-a0e0e60e5332@gmail.com>
On Thu, Aug 22, 2019 at 09:45:00PM +0100, Julien wrote:
> Hi Josh,
>
> On 22/08/19 21:04, Josh Poimboeuf wrote:
> > On Fri, Aug 16, 2019 at 01:23:52PM +0100, Raphael Gault wrote:
> > > On arm64 some object files contain data stored in the .text section.
> > > This data is interpreted by objtool as instruction but can't be
> > > identified as a valid one. In order to keep analysing those files we
> > > introduce INSN_UNKNOWN type. The "unknown instruction" warning will thus
> > > only be raised if such instructions are uncountered while validating an
> > > execution branch.
> > >
> > > This change doesn't impact the x86 decoding logic since 0 is still used
> > > as a way to specify an unknown type, raising the "unknown instruction"
> > > warning during the decoding phase still.
> > >
> > > Signed-off-by: Raphael Gault <raphael.gault@arm.com>
> >
> > Is there a reason such data can't be moved to .rodata? That would seem
> > like the proper fix.
> >
>
> Raphaël can confirm, if I remember correctly, that issue was encountered on
> assembly files implementing crypto algorithms were some words/double-words
> of data were in the middle of the .text. I think it is done this way to make
> sure the data can be loaded in a single instruction. So moving it to another
> section could impact the crypto performance depending on the relocations.
>
> That was my understanding at least.
Thanks. If that's the case then that would be useful information to put
in the patch description. A code excerpt of an example code site would
be useful too.
I'm not sure INSN_UNKNOWN is the right name though, since the decoder
does actually know about it. Maybe INSN_DATA or something?
--
Josh
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-22 21:51 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 12:23 [RFC v4 00/18] objtool: Add support for arm64 Raphael Gault
2019-08-16 12:23 ` [RFC v4 01/18] objtool: Add abstraction for computation of symbols offsets Raphael Gault
2019-08-22 16:30 ` Julien
2019-08-22 19:57 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 02/18] objtool: orc: Refactor ORC API for other architectures to implement Raphael Gault
2019-08-22 19:59 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 03/18] objtool: Move registers and control flow to arch-dependent code Raphael Gault
2019-08-22 20:00 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 04/18] objtool: arm64: Add required implementation for supporting the aarch64 architecture in objtool Raphael Gault
2019-08-22 20:00 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 05/18] objtool: special: Adapt special section handling Raphael Gault
2019-08-22 20:02 ` Josh Poimboeuf
2019-08-22 20:18 ` Julien
2019-08-16 12:23 ` [RFC v4 06/18] objtool: arm64: Adapt the stack frame checks for arm architecture Raphael Gault
2019-08-22 20:03 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 07/18] objtool: Introduce INSN_UNKNOWN type Raphael Gault
2019-08-22 20:04 ` Josh Poimboeuf
2019-08-22 20:45 ` Julien
2019-08-22 21:51 ` Josh Poimboeuf [this message]
2019-08-16 12:23 ` [RFC v4 08/18] objtool: Refactor switch-tables code to support other architectures Raphael Gault
2019-08-22 20:04 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 09/18] gcc-plugins: objtool: Add plugin to detect switch table on arm64 Raphael Gault
2019-08-22 20:05 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 10/18] objtool: arm64: Implement functions to add switch tables alternatives Raphael Gault
2019-08-23 16:35 ` Julien
2019-08-16 12:23 ` [RFC v4 11/18] arm64: alternative: Mark .altinstr_replacement as containing executable instructions Raphael Gault
2019-08-16 12:23 ` [RFC v4 12/18] arm64: assembler: Add macro to annotate asm function having non standard stack-frame Raphael Gault
2019-08-22 20:10 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 13/18] arm64: sleep: Prevent stack frame warnings from objtool Raphael Gault
2019-08-22 20:16 ` Josh Poimboeuf
2019-08-16 12:23 ` [RFC v4 14/18] arm64: kvm: Annotate non-standard stack frame functions Raphael Gault
2019-08-16 12:24 ` [RFC v4 15/18] arm64: kernel: Add exception on kuser32 to prevent stack analysis Raphael Gault
2019-08-16 12:24 ` [RFC v4 16/18] arm64: crypto: Add exceptions for crypto object " Raphael Gault
2019-08-22 20:19 ` Josh Poimboeuf
2019-08-16 12:24 ` [RFC v4 17/18] arm64: kernel: Annotate non-standard stack frame functions Raphael Gault
2019-08-16 12:24 ` [RFC v4 18/18] objtool: arm64: Enable stack validation for arm64 Raphael Gault
2019-08-22 19:56 ` [RFC v4 00/18] objtool: Add support " Josh Poimboeuf
2019-08-23 12:00 ` Raphael Gault
2019-10-14 8:37 ` Julien Thierry
2019-10-14 13:27 ` Raphaël Gault
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190822215112.n36slswph64nbzhb@treble \
--to=jpoimboe@redhat.com \
--cc=catalin.marinas@arm.com \
--cc=julien.thierry.kdev@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=raph.gault+kdev@gmail.com \
--cc=raphael.gault@arm.com \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).