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From:   Jim Wilson <jimw@sifive.com>
Date:   Tue, 13 Oct 2020 18:20:49 -0700
Message-ID: <CAFyWVaYORWYZTXyXOWiY6xK-SFTvsUxDNDqKQnhVUwzc5N045Q@mail.gmail.com>
Subject: Re: [PATCH 4/5] RISC-V: Protect .init.text & .init.data
To:     Atish Patra <atishp@atishpatra.org>
Cc:     Greentime Hu <greentime.hu@sifive.com>,
        Kito Cheng <kito.cheng@gmail.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Atish Patra <atish.patra@wdc.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Kees Cook <keescook@chromium.org>,
        Anup Patel <anup@brainfault.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Guo Ren <guoren@linux.alibaba.com>,
        Zong Li <zong.li@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@suse.de>,
        Michel Lespinasse <walken@google.com>,
        Ard Biesheuvel <ardb@kernel.org>
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On Tue, Oct 13, 2020 at 3:25 PM Atish Patra <atishp@atishpatra.org> wrote:
> This happens only when copy_from_user is called from function that is
> annotated with __init.
> Adding Kito & Jim for their input
>
> @kito, @Jim: Please let me know if I should create a issue in
> riscv-gnu-toolchain repo or somewhere else.

I can't do anything useful without a testcase that I can use to
reproduce the problem.  The interactions here are complex, so pointing
at lines of code or kernel config options doesn't give me any useful
info.

Relaxation can convert calls to a jal.  I don't know of any open bugs
in this area that can generate relocation errors.  if it is a
relaxation error then turning off relaxation should work around the
problem as you suggested.

A kernel build problem is serious.  I think this is worth a bug
report.  FSF binutils or riscv-gnu-toolchain is fine.

Jim