linux-kernel - Re: arch/arm/probes/kprobes/core.c:409:30: error: .fnstart must precede .save or .vsave directives

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Message-ID: <CAKwvOdkCCyP8W2pHf9ETKMgUtKCgcSwUb6=bMJ_8riwjyknpCw@mail.gmail.com>
Date:   Mon, 26 Sep 2022 11:17:00 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        open list <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        regressions@...ts.linux.dev, lkft-triage@...ts.linaro.org,
        llvm@...ts.linux.dev
Subject: Re: arch/arm/probes/kprobes/core.c:409:30: error: .fnstart must
 precede .save or .vsave directives

On Mon, Sep 26, 2022 at 11:02 AM Russell King (Oracle)
<linux@...linux.org.uk> wrote:
>
> On Mon, Sep 26, 2022 at 10:42:45AM -0700, Nick Desaulniers wrote:
> > > On Mon, Sep 26, 2022 at 08:44:05AM -0700, Nathan Chancellor wrote:
> > > > Thank you for the testing and report! I brought this up on GitHub on
> > > > Friday as I noticed this as well:
> > > >
> > > > https://github.com/ClangBuiltLinux/linux/issues/1718
> >
> > Thanks for the reports. I'll take a look at filing additional bug
> > reports against clang, then moving the definition of
> > __kretprobe_trampoline to out of line assembler.
>
> Are you saying that .save should be accepted without a .fnstart?

No. It's just a bug in clang's inline assembler. But it does make
sense to just move it to out of line assembler anyways; having it be
inline provides little to no benefit.

Should I be using UNWIND from arch/arm/include/asm/unwind.h on these
.fnstart/.save/.pad/.fnend directives?
-- 
Thanks,
~Nick Desaulniers