From: Will Deacon <will@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
dave.martin@arm.com, linux-arm-kernel@lists.infradead.org,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v2 07/10] arm64: asm: Provide a mechanism for generating ELF note for BTI
Date: Wed, 6 May 2020 14:44:34 +0100 [thread overview]
Message-ID: <20200506134433.GA12453@willie-the-truck> (raw)
In-Reply-To: <20200506123855.GC5299@sirena.org.uk>
On Wed, May 06, 2020 at 01:38:55PM +0100, Mark Brown wrote:
> On Wed, May 06, 2020 at 12:26:33PM +0100, Will Deacon wrote:
> > On Tue, May 05, 2020 at 06:06:29PM +0100, Mark Brown wrote:
>
> > > I was unsure about that - it'd be a bit annoying to have to have all the
> > > callers of the macro list things like BTI where
>
> > It just feels inevitable that we'll need to do this at some point!
> > Do you know what is supposed to happen if an object has multiple instances
> > of this property identifying different features? For example, could we
> > do something like:
>
> Regardless of what is supposed to happen my strong suspicion is that
> we'll have some more.
Yup! :)
> > If we have to merge this stuff in a single .long, then I think we'll
> > probably have to put up with passing in the features as an optional macro
> > argument, which defaults to "all features" if it's omitted. So on top of
> > your patches, we could do:
>
> > +#define GNU_PROPERTY_AARCH64_FEATURE_1_ALL \
> > + (GNU_PROPERTY_AARCH64_FEATURE_1_BTI | \
> > + GNU_PROPERTY_AARCH64_FEATURE_1_PAC)
> > +
> > +.macro emit_aarch64_feature_1_and, feat=GNU_PROPERTY_AARCH64_FEATURE_1_ALL
>
> Right, I was just expecting to have the ifdefs selecting the flags to
> emit in the middle of the asm macro definiton rather than separately - I
> didn't see a huge win in defining a macro with the only user being
> another macro. I can do something along those lines though.
With my suggestion, we still only have the 'emit_aarch64_feature_1_and'
macro, it just provides a way to override the properties if we need that
later on. All I'm proposing is adding the optional feat parameter, which
defaults to all of the properties we know about.
> > -.macro emit_aarch64_feature_1_and
> > +.macro emit_aarch64_feature_1_and, feat=0
> > .endm
>
> That will result in us emitting the note with no flags set which
> *should* be totally fine but is a bit unusual and feels like tempting
> fate.
Nah, that's just the dummy .macro definition.
Will
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next prev parent reply other threads:[~2020-05-06 13:44 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 21:16 [PATCH v2 00/10] arm64: BTI kernel and vDSO support Mark Brown
2020-04-29 21:16 ` [PATCH v2 01/10] arm64: bti: Support building kernel C code using BTI Mark Brown
2020-05-05 16:50 ` Dave Martin
2020-05-05 17:31 ` Mark Brown
2020-05-06 12:24 ` Amit Kachhap
2020-04-29 21:16 ` [PATCH v2 02/10] arm64: asm: Override SYM_FUNC_START when building the kernel with BTI Mark Brown
2020-05-05 14:56 ` Will Deacon
2020-05-05 15:18 ` Mark Brown
2020-05-05 16:08 ` Will Deacon
2020-05-05 17:21 ` Mark Brown
2020-05-06 7:10 ` Will Deacon
2020-05-06 10:41 ` Mark Brown
2020-05-06 10:50 ` Will Deacon
2020-05-06 11:43 ` Mark Brown
2020-05-06 12:27 ` Will Deacon
2020-05-06 13:03 ` Mark Brown
2020-05-06 13:40 ` Dave Martin
2020-05-06 14:45 ` Will Deacon
2020-05-06 15:25 ` Mark Brown
2020-05-06 15:48 ` Will Deacon
2020-05-06 15:33 ` Dave Martin
2020-04-29 21:16 ` [PATCH v2 03/10] arm64: Set GP bit in kernel page tables to enable BTI for the kernel Mark Brown
2020-04-29 21:16 ` [PATCH v2 04/10] arm64: bpf: Annotate JITed code for BTI Mark Brown
2020-04-29 21:16 ` [PATCH v2 05/10] arm64: mm: Mark executable text as guarded pages Mark Brown
2020-04-29 21:16 ` [PATCH v2 06/10] arm64: bti: Provide Kconfig for kernel mode BTI Mark Brown
2020-04-29 21:16 ` [PATCH v2 07/10] arm64: asm: Provide a mechanism for generating ELF note for BTI Mark Brown
2020-05-05 14:58 ` Will Deacon
2020-05-05 16:51 ` Dave Martin
2020-05-05 17:06 ` Mark Brown
2020-05-06 11:26 ` Will Deacon
2020-05-06 12:38 ` Mark Brown
2020-05-06 13:44 ` Will Deacon [this message]
2020-05-06 15:39 ` Mark Brown
2020-04-29 21:16 ` [PATCH v2 08/10] arm64: vdso: Annotate " Mark Brown
2020-04-29 21:16 ` [PATCH v2 09/10] arm64: vdso: Force the vDSO to be linked as BTI when built " Mark Brown
2020-04-29 21:16 ` [PATCH v2 10/10] arm64: vdso: Map the vDSO text with guarded pages " Mark Brown
2020-04-30 17:18 ` [PATCH v2 00/10] arm64: BTI kernel and vDSO support Catalin Marinas
2020-04-30 17:23 ` Mark Brown
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