From: Gary Guo <gary@garyguo.net>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, patches@lists.linux.dev,
"Jarkko Sakkinen" <jarkko@kernel.org>,
"Alex Gaynor" <alex.gaynor@gmail.com>,
"Wedson Almeida Filho" <wedsonaf@google.com>,
"Sven Van Asbroeck" <thesven73@gmail.com>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Ard Biesheuvel" <ardb@kernel.org>
Subject: Re: [PATCH v9 09/27] rust: add `compiler_builtins` crate
Date: Mon, 29 Aug 2022 18:11:33 +0100 [thread overview]
Message-ID: <20220829181133.00005f01@garyguo.net> (raw)
In-Reply-To: <CAKwvOdkc0Qhwu=gfe1+H23TnAa6jnO6A3ZCO687dH6mSrATmDA@mail.gmail.com>
On Wed, 24 Aug 2022 11:38:46 -0700
Nick Desaulniers <ndesaulniers@google.com> wrote:
> Another idea I had, and Ard mentioned to me this morning that efistub
> does something similar:
>
> I think objcopy can rename symbol references. So instead of calling
> foo, I think you can use objcopy to call bar instead.
>
> To avoid the case of Rust core refering to symbols typically provided
> by the --rtlib={libgcc|compiler-rt}, what if we:
> 1. build core.o (with reference to the unfavorable symbols)
> 2. use objcopy to rename references in core.o to the symbols listed in
> this file; maybe prepend them with `rust_core_` or something.
> 3. provide this crate with panic'ing definitions, but for the renamed
> symbols.
>
> That way, enabling CONFIG_RUST=y won't hide the case where C code is
> triggering such libcalls from the C compiler?
>
> To restate the concern, I don't want CONFIG_RUST=y to hide that fact
> that someone wrote `float x, y; if (x != y) ...` in C code, where the
> C compiler will likely lower that to a libcall to __nesf2 since with
> the current approach in this patch, linkage would proceed. The current
> behavior is to intentionally fail to link. I think what I describe
> above may work to keep this intended behavior of the kernel's build
> system.
>
> Ah, looks like there's objcopy flags:
> --redefine-sym old=new
> Change the name of a symbol old, to new. This can be
> useful when one is trying link
> two things together for which you have no source, and there
> are name collisions.
>
> --redefine-syms=filename
> Apply --redefine-sym to each symbol pair "old new" listed
> in the file filename.
> filename is simply a flat file, with one symbol pair per
> line. Line comments may be
> introduced by the hash character. This option may be given
> more than once.
>
> So probably could start with my diff from above, but use
> --redefine-syms=filename instead of --strip-symbols=.
>
> --
> Thanks,
> ~Nick Desaulniers
This is the approach we are about to take, see
https://github.com/Rust-for-Linux/linux/pull/779.
It's easy for just one symbol that is known to be not defined, but it
can be more complex as some of these symbols can be defined on a
platform but not another, so we would have to generate a dynamic list
of what symbols to "hijack" depending on the config. Currently we
avoid this issue by having all symbols in compiler_builtins
crate weak, but we couldn't weakly redefine a symbol.
It's certainly doable, though, but it require some effort. I am
not quite available recently so hadn't further extend and polish my
patch.
Best,
Gary
next prev parent reply other threads:[~2022-08-29 17:13 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 15:41 [PATCH v9 00/27] Rust support Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 01/27] kallsyms: use `sizeof` instead of hardcoded size Miguel Ojeda
2022-08-05 16:48 ` Geert Stappers
2022-08-05 18:46 ` Miguel Ojeda
2022-08-05 22:40 ` Konstantin Shelekhin
2022-08-17 19:36 ` Kees Cook
2022-08-18 9:03 ` Konstantin Shelekhin
2022-08-18 16:03 ` Kees Cook
2022-09-27 12:48 ` Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 02/27] kallsyms: avoid hardcoding buffer size Miguel Ojeda
2022-08-17 19:37 ` Kees Cook
2022-08-18 16:50 ` Geert Stappers
2022-08-05 15:41 ` [PATCH v9 03/27] kallsyms: add static relationship between `KSYM_NAME_LEN{,_BUFFER}` Miguel Ojeda
2022-08-17 19:39 ` Kees Cook
2022-08-17 19:50 ` Boqun Feng
2022-08-17 20:31 ` Kees Cook
2022-08-17 20:45 ` Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 04/27] kallsyms: support "big" kernel symbols Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 05/27] kallsyms: increase maximum kernel symbol length to 512 Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 06/27] rust: add C helpers Miguel Ojeda
2022-08-17 19:44 ` Kees Cook
2022-08-17 20:22 ` Miguel Ojeda
2022-08-17 20:34 ` Kees Cook
2022-08-17 21:44 ` Miguel Ojeda
2022-08-17 23:56 ` Kees Cook
2022-08-18 16:03 ` Miguel Ojeda
2022-08-18 16:08 ` Kees Cook
2022-08-18 17:01 ` Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 08/27] rust: adapt `alloc` crate to the kernel Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 09/27] rust: add `compiler_builtins` crate Miguel Ojeda
2022-08-17 20:08 ` Kees Cook
2022-08-22 23:55 ` Nick Desaulniers
2022-08-24 18:38 ` Nick Desaulniers
2022-08-29 17:11 ` Gary Guo [this message]
2022-08-05 15:41 ` [PATCH v9 10/27] rust: add `macros` crate Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 11/27] rust: add `bindings` crate Miguel Ojeda
2022-08-05 15:41 ` [PATCH v9 12/27] rust: add `kernel` crate Miguel Ojeda
2022-08-06 10:24 ` Konstantin Shelekhin
2022-08-06 11:22 ` Miguel Ojeda
2022-08-06 12:15 ` Konstantin Shelekhin
2022-08-06 14:57 ` Matthew Wilcox
2022-09-19 14:07 ` Wedson Almeida Filho
2022-09-19 16:09 ` Linus Torvalds
2022-09-19 17:20 ` Linus Torvalds
2022-09-19 18:05 ` Wedson Almeida Filho
2022-09-19 20:42 ` Linus Torvalds
2022-09-19 22:35 ` Wedson Almeida Filho
2022-09-19 23:39 ` Linus Torvalds
2022-09-19 23:50 ` Alex Gaynor
2022-09-19 23:58 ` Linus Torvalds
2022-09-20 0:15 ` Linus Torvalds
2022-09-20 15:55 ` Eric W. Biederman
2022-09-20 22:39 ` Gary Guo
2022-09-21 6:42 ` comex
2022-09-21 14:19 ` Boqun Feng
2022-10-03 2:03 ` comex
2022-09-20 0:40 ` Boqun Feng
2022-10-03 4:17 ` Kyle Strand
2022-09-20 0:41 ` Wedson Almeida Filho
2022-09-21 11:23 ` Konstantin Shelekhin
2022-09-21 11:46 ` Greg KH
2022-08-05 15:41 ` [PATCH v9 13/27] rust: export generated symbols Miguel Ojeda
2022-08-17 20:11 ` Kees Cook
2022-08-05 15:41 ` [PATCH v9 14/27] vsprintf: add new `%pA` format specifier Miguel Ojeda
2022-08-05 15:42 ` [PATCH v9 15/27] scripts: checkpatch: diagnose uses of `%pA` in the C side as errors Miguel Ojeda
2022-08-05 15:42 ` [PATCH v9 16/27] scripts: checkpatch: enable language-independent checks for Rust Miguel Ojeda
2022-08-17 20:12 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 17/27] scripts: decode_stacktrace: demangle Rust symbols Miguel Ojeda
2022-08-05 15:42 ` [PATCH v9 18/27] scripts: add `generate_rust_analyzer.py` Miguel Ojeda
2022-08-17 20:13 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 19/27] scripts: add `generate_rust_target.rs` Miguel Ojeda
2022-08-17 20:14 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 20/27] scripts: add `rust_is_available.sh` Miguel Ojeda
2022-08-17 20:18 ` Kees Cook
2022-08-17 20:40 ` Miguel Ojeda
2022-08-22 20:09 ` Nick Desaulniers
2022-08-23 12:12 ` Miguel Ojeda
2022-08-23 12:16 ` Miguel Ojeda
2022-08-05 15:42 ` [PATCH v9 21/27] scripts: add `is_rust_module.sh` Miguel Ojeda
2022-08-17 20:19 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 22/27] rust: add `.rustfmt.toml` Miguel Ojeda
2022-08-17 20:19 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 23/27] Kbuild: add Rust support Miguel Ojeda
2022-08-17 20:26 ` Kees Cook
2022-08-17 20:56 ` Miguel Ojeda
2022-08-22 22:35 ` Nick Desaulniers
2022-09-12 16:07 ` Masahiro Yamada
2022-09-12 16:18 ` Miguel Ojeda
2022-09-13 6:37 ` Masahiro Yamada
2022-08-05 15:42 ` [PATCH v9 24/27] docs: add Rust documentation Miguel Ojeda
2022-08-05 15:42 ` [PATCH v9 25/27] x86: enable initial Rust support Miguel Ojeda
2022-08-17 20:27 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 26/27] samples: add first Rust examples Miguel Ojeda
2022-08-06 13:14 ` Konstantin Shelekhin
2022-08-17 21:02 ` Miguel Ojeda
2022-08-18 9:04 ` Konstantin Shelekhin
2022-08-17 20:28 ` Kees Cook
2022-08-05 15:42 ` [PATCH v9 27/27] MAINTAINERS: Rust Miguel Ojeda
2022-08-17 20:28 ` Kees Cook
2022-08-17 20:43 ` Miguel Ojeda
[not found] ` <20220805154231.31257-8-ojeda@kernel.org>
2022-08-17 20:07 ` [PATCH v9 07/27] rust: import upstream `alloc` crate Kees Cook
2022-08-17 21:00 ` Miguel Ojeda
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=20220829181133.00005f01@garyguo.net \
--to=gary@garyguo.net \
--cc=alex.gaynor@gmail.com \
--cc=ardb@kernel.org \
--cc=bjorn3_gh@protonmail.com \
--cc=boqun.feng@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=jarkko@kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=ndesaulniers@google.com \
--cc=ojeda@kernel.org \
--cc=patches@lists.linux.dev \
--cc=rust-for-linux@vger.kernel.org \
--cc=thesven73@gmail.com \
--cc=torvalds@linux-foundation.org \
--cc=wedsonaf@google.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).