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Message-ID: <Y1ERsP0YYVNulWnw@FVFF77S0Q05N>
Date: Thu, 20 Oct 2022 10:15:28 +0100
From: Mark Rutland <mark.rutland@....com>
To: Guo Ren <guoren@...nel.org>
Cc: arnd@...db.de, palmer@...osinc.com, tglx@...utronix.de,
peterz@...radead.org, luto@...nel.org, conor.dooley@...rochip.com,
heiko@...ech.de, jszhang@...nel.org, lazyparser@...il.com,
falcon@...ylab.org, chenhuacai@...nel.org, apatel@...tanamicro.com,
atishp@...shpatra.org, palmer@...belt.com,
paul.walmsley@...ive.com, zouyipeng@...wei.com,
bigeasy@...utronix.de, David.Laight@...lab.com,
chenzhongjin@...wei.com, linux-arch@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
Lai Jiangshan <laijs@...ux.alibaba.com>,
Borislav Petkov <bp@...en8.de>,
Miguel Ojeda <ojeda@...nel.org>,
Kees Cook <keescook@...omium.org>,
Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH V6 04/11] compiler_types.h: Add __noinstr_section() for
noinstr
On Sat, Oct 08, 2022 at 09:54:39AM +0800, Guo Ren wrote:
> On Mon, Oct 3, 2022 at 7:39 PM Mark Rutland <mark.rutland@....com> wrote:
> >
> > On Sat, Oct 01, 2022 at 09:24:44PM -0400, guoren@...nel.org wrote:
> > > From: Lai Jiangshan <laijs@...ux.alibaba.com>
> > >
> > > And it will be extended for C entry code.
> > >
> > > Cc: Borislav Petkov <bp@...en8.de>
> > > Reviewed-by: Miguel Ojeda <ojeda@...nel.org>
> > > Reviewed-by: Kees Cook <keescook@...omium.org>
> > > Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > Suggested-by: Peter Zijlstra <peterz@...radead.org>
> > > Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
> > > ---
> > > include/linux/compiler_types.h | 8 +++++---
> > > 1 file changed, 5 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> > > index 4f2a819fd60a..e9ce11ea4d8b 100644
> > > --- a/include/linux/compiler_types.h
> > > +++ b/include/linux/compiler_types.h
> > > @@ -227,9 +227,11 @@ struct ftrace_likely_data {
> > > #endif
> > >
> > > /* Section for code which can't be instrumented at all */
> > > -#define noinstr \
> > > - noinline notrace __attribute((__section__(".noinstr.text"))) \
> > > - __no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage
> > > +#define __noinstr_section(section) \
> > > + noinline notrace __section(section) __no_profile \
> > > + __no_kcsan __no_sanitize_address __no_sanitize_coverage
> > > +
> > > +#define noinstr __noinstr_section(".noinstr.text")
> >
> > One thing proably worth noting here is that while KPROBES will avoid
> > instrumenting `.noinstr.text`, that won't happen automatically for other
> > __noinstr_section() sections, and that will need to be inhibited through other
> > means (e.g. the kprobes blacklist, explicit NOKPROBE_SYMBOL() annotation, or
> > otherwise).
>
> In riscv, "we select HAVE_KPROBES if !XIP_KERNEL", so don't worry
> about that. I don't think we could enable kprobe for XIP_KERNEL in the
> future.
Sure; but someone else might use __noinstr_section() elsewhere where this could
matter, and I was suggesting that we could add a comment as above.
Thanks,
Mark.
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