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From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Andrey Konovalov <andreyknvl@google.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Kostya Serebryany <kcc@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Peter Collingbourne <pcc@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH v2] arm64: Expose original FAR_EL1 value in sigcontext
Date: Fri, 27 Mar 2020 11:39:00 +0000	[thread overview]
Message-ID: <20200327113859.GA18117@mbp> (raw)
In-Reply-To: <20200327075655.GA32241@willie-the-truck>

On Fri, Mar 27, 2020 at 07:56:56AM +0000, Will Deacon wrote:
> On Thu, Mar 26, 2020 at 04:45:39PM +0000, Catalin Marinas wrote:
> > On Wed, Mar 25, 2020 at 10:40:01AM -0700, Peter Collingbourne wrote:
> > > The kernel currently clears the tag bits (i.e. bits 56-63) in the fault
> > > address exposed via siginfo.si_addr and sigcontext.fault_address. However,
> > > the tag bits may be needed by tools in order to accurately diagnose
> > > memory errors, such as HWASan [1] or future tools based on the Memory
> > > Tagging Extension (MTE).
> > > 
> > > We should not stop clearing these bits in the existing fault address
> > > fields, because there may be existing userspace applications that are
> > > expecting the tag bits to be cleared. Instead, create a far_context in
> > > sigcontext (similar to the existing esr_context), and store the original
> > > value of FAR_EL1 (including the tag bits) there.
> > > 
> > > [1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
> > > 
> > > Signed-off-by: Peter Collingbourne <pcc@google.com>
> > 
> > The patch looks fine. However, I wouldn't queue it for 5.7, it's too
> > close to the merging window and I'd like it to sit in linux-next for a
> > bit. Unless there are other comments, it looks fine to me for -rc8.
> 
> You mean 5.8?

Yes.

> I'm also a bit surprised not to see a docs update, given that
> we talk about the general lack of tags in siginfo_t towards the end of
> Documentation/arm64/tagged-pointers.rst

Good point. It's worth adding this to the tagged-pointers.rst document
since the only use of the raw FAR_EL1 is for tagged pointers.

-- 
Catalin

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  reply	other threads:[~2020-03-27 11:39 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12 17:17 [PATCH] arm64: Expose original FAR_EL1 value in sigcontext Peter Collingbourne
2020-03-25 13:10 ` Catalin Marinas
2020-03-25 17:41   ` Peter Collingbourne
2020-03-25 17:40 ` [PATCH v2] " Peter Collingbourne
2020-03-26 16:45   ` Catalin Marinas
2020-03-27  7:56     ` Will Deacon
2020-03-27 11:39       ` Catalin Marinas [this message]
2020-03-27 19:26         ` Peter Collingbourne
2020-03-27 19:19   ` [PATCH v3] " Peter Collingbourne
2020-04-22 14:25     ` Catalin Marinas
2020-04-29 21:08     ` Will Deacon
2020-04-29 21:42       ` Peter Collingbourne
2020-05-04 17:03         ` Will Deacon
2020-05-07 17:57           ` [PATCH v4] arm64: Expose FAR_EL1 tag bits " Peter Collingbourne
2020-05-08  2:01             ` [PATCH v5] " Peter Collingbourne
2020-05-12 16:25               ` Catalin Marinas
2020-05-13 18:09               ` [PATCH v6] " Peter Collingbourne
2020-05-13 20:28                 ` Dave Martin
2020-05-15  0:58                   ` Peter Collingbourne
2020-05-18  9:53                     ` Dave Martin
2020-05-19 22:00                       ` Peter Collingbourne
2020-05-20  8:55                         ` Will Deacon
2020-05-20  9:26                           ` Dave Martin
2020-05-21  2:28                             ` Peter Collingbourne
2020-05-21  2:29                               ` [PATCH v6 0/3] " Peter Collingbourne
2020-05-21  2:29                                 ` [PATCH v6 1/3] signal: Allow architectures to store arch-specific data in kernel_siginfo Peter Collingbourne
2020-05-21  2:29                                 ` [PATCH v6 2/3] arm64: Move fault address and fault code into kernel_siginfo Peter Collingbourne
2020-05-21 13:34                                   ` kbuild test robot
2020-05-21  2:29                                 ` [PATCH v6 3/3] arm64: Expose FAR_EL1 tag bits in sigcontext Peter Collingbourne
2020-05-21 12:35                               ` [PATCH v6] " Eric W. Biederman
2020-05-21 18:03                                 ` Peter Collingbourne
2020-05-21 19:24                                   ` Eric W. Biederman
2020-05-21 20:48                                     ` Peter Collingbourne
2020-06-08 18:12                                       ` Peter Collingbourne
2020-06-08 18:14                                         ` [PATCH v7] arm64: Expose FAR_EL1 tag bits in siginfo Peter Collingbourne
     [not found]                                           ` <20200623020134.16655-1-pcc@google.com>
     [not found]                                             ` <87sgemrlgc.fsf@x220.int.ebiederm.org>
2020-06-23 14:38                                               ` [PATCH v8] " Dave Martin
2020-06-23 17:47                                                 ` Eric W. Biederman
2020-06-24  0:40                                                   ` Peter Collingbourne
2020-06-24  9:28                                                     ` Dave Martin
2020-06-24 16:51                                                       ` Peter Collingbourne
2020-06-24 17:12                                                         ` Dave Martin
2020-06-24 19:51                                                           ` Peter Collingbourne
2020-07-06 16:41                                                             ` Dave Martin
2020-07-06 19:20                                                               ` Peter Collingbourne
2020-07-07 14:19                                                                 ` Dave Martin
2020-07-07 19:07                                                                   ` Peter Collingbourne
2020-07-08 11:00                                                                     ` Dave Martin
2020-07-08 13:58                                                                       ` Dave Martin
2020-07-08 22:21                                                                         ` Peter Collingbourne
2020-07-13 13:24                                                                           ` Dave Martin
2020-07-13 20:50                                                                             ` Peter Collingbourne
2020-07-14 17:36                                                                               ` Dave Martin
2020-08-18  3:16                                                                                 ` Peter Collingbourne
2020-08-18 13:50                                                                                   ` Dave Martin
2020-06-23 14:57                                             ` Dave Martin
2020-05-26 13:03                                     ` [PATCH v6] arm64: Expose FAR_EL1 tag bits in sigcontext Dave Martin
2020-04-30  9:50       ` [PATCH v3] arm64: Expose original FAR_EL1 value " Catalin Marinas
2020-04-30  9:59         ` Will Deacon
2020-04-30 13:34           ` Catalin Marinas
2020-05-04 10:19     ` Dave Martin
2020-05-07 17:55       ` Peter Collingbourne
2020-05-13 17:27         ` Dave Martin
2020-05-13 18:00           ` Peter Collingbourne

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