From: Catalin Marinas <firstname.lastname@example.org> To: Mark Brown <email@example.com> Cc: Dave Martin <Dave.Martin@arm.com>, Will Deacon <firstname.lastname@example.org>, Szabolcs Nagy <email@example.com>, Jeremy Linton <firstname.lastname@example.org>, "H . J . Lu" <email@example.com>, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH v1 2/2] arm64: Enable BTI for main executable as well as the interpreter Date: Thu, 3 Jun 2021 19:04:31 +0100 [thread overview] Message-ID: <20210603180429.GI20338@arm.com> (raw) In-Reply-To: <20210603165134.GF4257@sirena.org.uk> On Thu, Jun 03, 2021 at 05:51:34PM +0100, Mark Brown wrote: > On Thu, Jun 03, 2021 at 04:40:35PM +0100, Dave Martin wrote: > > Do we know how libcs will detect that they don't need to do the > > mprotect() calls? Do we need a detection mechanism at all? > > > > Ignoring certain errors from mprotect() when ld.so is trying to set > > PROT_BTI on the main executable's code pages is probably a reasonable, > > backwards-compatible compromise here, but it seems a bit wasteful. > > I think the theory was that they would just do the mprotect() calls and > ignore any errors as they currently do, or declare that they depend on a > new enough kernel version I guess (not an option for glibc but might be > for others which didn't do BTI yet). I think we discussed the possibility of an AT_FLAGS bit. Until recently, this field was 0 but it gained a new bit now. If we are to expose this to arch-specific things, it may need some reservations. Anyway, that's an optimisation that can be added subsequently. -- Catalin _______________________________________________ linux-arm-kernel mailing list email@example.com http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-03 18:06 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-21 14:46 [PATCH v1 0/2] arm64: Enable BTI for the " Mark Brown 2021-05-21 14:46 ` [PATCH v1 1/2] elf: Allow architectures to parse properties on the main executable Mark Brown 2021-06-03 15:40 ` Dave Martin 2021-06-03 18:52 ` Mark Brown 2021-05-21 14:46 ` [PATCH v1 2/2] arm64: Enable BTI for main executable as well as the interpreter Mark Brown 2021-06-03 15:40 ` Dave Martin 2021-06-03 16:51 ` Mark Brown 2021-06-03 18:04 ` Catalin Marinas [this message] 2021-06-07 11:25 ` Dave Martin 2021-06-07 18:12 ` Catalin Marinas 2021-06-08 11:33 ` Mark Brown 2021-06-08 15:19 ` Dave Martin 2021-06-08 15:42 ` Jeremy Linton 2021-06-10 10:33 ` Dave Martin
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