linux-kernel - Re: [RFC PATCH 11/12] selftests/fpu: Move FP code to a separate translation unit

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZXc2W1Rl+S/UWAK3@infradead.org>
Date:   Mon, 11 Dec 2023 08:18:35 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Samuel Holland <samuel.holland@...ive.com>
Cc:     linux-arm-kernel@...ts.infradead.org, loongarch@...ts.linux.dev,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
        linux-riscv@...ts.infradead.org,
        Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        linux-arch@...r.kernel.org, Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        linux-kbuild@...r.kernel.org
Subject: Re: [RFC PATCH 11/12] selftests/fpu: Move FP code to a separate
 translation unit

>  obj-$(CONFIG_TEST_FPU) += test_fpu.o
> -CFLAGS_test_fpu.o += $(FPU_CFLAGS)
> +test_fpu-y := test_fpu_glue.o test_fpu_impl.o
> +CFLAGS_test_fpu_impl.o += $(FPU_CFLAGS)

Btw, I really wonder if having a

modname-fpu += foo.o

syntax in kbuild wouldn't be preferable to this.  Of coure that requires
someone who understands kbuild inside out.

> +int test_fpu(void);

This needs to go into a header.

And I think I underatand your way to enforce the use of a separate
compilation unit in the riscv patch now.

Can we just make that generic, e.g. have a <linux/fpu.h> that wraps
<asm/fpu.h> that does the guard based on a
-D_LINUX_FPU_COMPILATION_UNIT=1 on the command line so that all the
code becomes fully portable?  Any legacy arch specific fpu users not
using <linux/fpu.h> would not be affected by it, although it would be
great to eventually migrate them to the common scheme.