From: Nathan Chancellor <nathan@kernel.org>
To: Dan Li <ashimida@linux.alibaba.com>
Cc: catalin.marinas@arm.com, will@kernel.org,
ndesaulniers@google.com, keescook@chromium.org,
masahiroy@kernel.org, tglx@linutronix.de,
akpm@linux-foundation.org, mark.rutland@arm.com,
samitolvanen@google.com, npiggin@gmail.com, linux@roeck-us.net,
mhiramat@kernel.org, ojeda@kernel.org,
luc.vanoostenryck@gmail.com, elver@google.com,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] [PATCH] AARCH64: Add gcc Shadow Call Stack support
Date: Wed, 23 Feb 2022 10:39:35 -0700 [thread overview]
Message-ID: <YhZxVwoshSwwJkJO@dev-arch.archlinux-ax161> (raw)
In-Reply-To: <69d351c6-a69d-6ebb-53bc-b46dfe4da08a@linux.alibaba.com>
On Wed, Feb 23, 2022 at 12:50:21AM -0800, Dan Li wrote:
>
>
> On 2/22/22 08:16, Nathan Chancellor wrote:
> > On Tue, Feb 22, 2022 at 01:57:36AM -0800, Dan Li wrote:
> > > Shadow call stack is available in GCC > 11.2.0, this patch makes
> > > the corresponding kernel configuration available when compiling
> > > the kernel with gcc.
> > > config SHADOW_CALL_STACK
> > > - bool "Clang Shadow Call Stack"
> > > - depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK
> > > + bool "Shadow Call Stack"
> > > + depends on ARCH_SUPPORTS_SHADOW_CALL_STACK
> > > depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER
> > > help
> > > - This option enables Clang's Shadow Call Stack, which uses a
> > > + This option enables Clang/GCC's Shadow Call Stack, which uses a
> >
> > I wonder if we want to just ditch the mention of the compiler if both
> > support it?
> >
>
> My intention is to remind users that this is a compiler feature.
> But since there is also a hint in CC_HAVE_SHADOW_CALL_STACK:
> +# Supported by clang >= 7.0 or GCC ...
>
> Removing the specific compiler here also looks fine to me.
> Would this look better?
>
> "This option enables Shadow Call Stack, which uses a ..."
>
> or maybe:
>
> "This option enables compiler's Shadow Call Stack, which uses a ..."
I do not honestly have a strong opinion around removing mention of the
compiler so either looks fine to me (might be better to say "the
compiler's Shadow ..." in the second one).
> > > shadow stack to protect function return addresses from being
> > > overwritten by an attacker. More information can be found in
> > > Clang's documentation:
> > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > > index 09b885cc4db5..a48a604301aa 100644
> > > --- a/arch/arm64/Kconfig
> > > +++ b/arch/arm64/Kconfig
> > > @@ -1255,7 +1255,7 @@ config HW_PERF_EVENTS
> > > config ARCH_HAS_FILTER_PGPROT
> > > def_bool y
> > > -# Supported by clang >= 7.0
> > > +# Supported by clang >= 7.0 or GCC > 11.2.0
> >
> > Same thing here, although eventually there may be a minimum GCC version
> > bump to something newer than 11.2.0, which would allow us to just drop
> > CONFIG_CC_HAVE_SHADOW_CALL_STACK altogether. No strong opinion.
> >
>
> As Guenter said, I thought maybe we could mark the minimum available
> version for users :)
Yes, that is what I was getting at with the "minimum version" comment.
It should remain around.
Cheers,
Nathan
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next prev parent reply other threads:[~2022-02-23 17:41 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-22 9:57 [PATCH] [PATCH] AARCH64: Add gcc Shadow Call Stack support Dan Li
2022-02-22 16:16 ` Nathan Chancellor
2022-02-22 16:47 ` Guenter Roeck
2022-02-22 16:59 ` Miguel Ojeda
2022-02-23 8:58 ` Dan Li
2022-02-23 8:55 ` Dan Li
2022-02-23 8:50 ` Dan Li
2022-02-23 17:39 ` Nathan Chancellor [this message]
2022-02-25 0:34 ` Dan Li
2022-02-22 18:47 ` Mark Rutland
2022-02-23 9:06 ` Dan Li
2022-02-23 11:48 ` Ard Biesheuvel
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