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From: Catalin Marinas <catalin.marinas@arm.com>
To: Luis Machado <luis.machado@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Will Deacon <will@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Szabolcs Nagy <szabolcs.nagy@arm.com>,
	Richard Earnshaw <Richard.Earnshaw@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Peter Collingbourne <pcc@google.com>,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	Alan Hayward <Alan.Hayward@arm.com>,
	Omair Javaid <omair.javaid@linaro.org>
Subject: Re: [PATCH v3 19/23] arm64: mte: Add PTRACE_{PEEK,POKE}MTETAGS support
Date: Wed, 13 May 2020 18:11:35 +0100	[thread overview]
Message-ID: <20200513171134.GE2719@gaia> (raw)
In-Reply-To: <e7f995d6-d48b-1ea2-c9e6-d2533e8eadd5@linaro.org>

On Wed, May 13, 2020 at 01:45:27PM -0300, Luis Machado wrote:
> On 5/13/20 12:09 PM, Luis Machado wrote:
> > Let me think about this for a bit. I'm trying to factor in the
> > /proc/<pid>/maps contents. If debuggers know which pages have PROT_MTE
> > set, then we can teach the tools not to PEEK/POKE tags from/to those
> > memory ranges, which simplifies the error handling a bit.
> 
> I was checking the output of /proc/<pid>/maps and it doesn't seem to contain
> flags against which i can match PROT_MTE. It seems /proc/<pid>/smaps is the
> one that contains the flags (mt) for MTE. Am i missing something?

You are right, the smaps is the one with the MTE information.

> Is this the only place debuggers can check for PROT_MTE? If so, that's
> unfortunate. /proc/<pid>/smaps doesn't seem to be convenient for parsing.

We can't change 'maps' as it's a pretty standard format with rwxp
properties only.

If you don't want to check any /proc file, just attempt to read the tags
and check the ptrace return code. The downside is that you can't easily
probe if a process is using MTE or not. But is this piece of information
relevant? The gdb user should know what to look for (well, it's been a
while since I used a debugger ;)).

-- 
Catalin


  reply	other threads:[~2020-05-13 17:11 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 14:25 [PATCH v3 00/23] arm64: Memory Tagging Extension user-space support Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 01/23] arm64: alternative: Allow alternative_insn to always issue the first instruction Catalin Marinas
2020-04-27 16:57   ` Dave Martin
2020-04-28 11:43     ` Catalin Marinas
2020-04-29 10:26       ` Dave Martin
2020-04-29 14:04         ` Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 02/23] arm64: mte: system register definitions Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 03/23] arm64: mte: CPU feature detection and initial sysreg configuration Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 04/23] arm64: mte: Use Normal Tagged attributes for the linear map Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 05/23] arm64: mte: Assembler macros and default architecture for .S files Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 06/23] arm64: mte: Tags-aware clear_page() implementation Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 07/23] arm64: mte: Tags-aware copy_page() implementation Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 08/23] arm64: Tags-aware memcmp_pages() implementation Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 09/23] arm64: mte: Add specific SIGSEGV codes Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 10/23] arm64: mte: Handle synchronous and asynchronous tag check faults Catalin Marinas
2020-04-23 10:38   ` Catalin Marinas
2020-04-27 16:58   ` Dave Martin
2020-04-28 13:43     ` Catalin Marinas
2020-04-29 10:26       ` Dave Martin
2020-04-21 14:25 ` [PATCH v3 11/23] mm: Introduce arch_calc_vm_flag_bits() Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 12/23] arm64: mte: Add PROT_MTE support to mmap() and mprotect() Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 13/23] mm: Introduce arch_validate_flags() Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 14/23] arm64: mte: Validate the PROT_MTE request via arch_validate_flags() Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 15/23] mm: Allow arm64 mmap(PROT_MTE) on RAM-based files Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 16/23] arm64: mte: Allow user control of the tag check mode via prctl() Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 17/23] arm64: mte: Allow user control of the generated random tags " Catalin Marinas
2020-04-21 14:25 ` [PATCH v3 18/23] arm64: mte: Restore the GCR_EL1 register after a suspend Catalin Marinas
2020-04-23 15:23   ` Lorenzo Pieralisi
2020-04-21 14:25 ` [PATCH v3 19/23] arm64: mte: Add PTRACE_{PEEK,POKE}MTETAGS support Catalin Marinas
2020-04-24 23:28   ` Peter Collingbourne
2020-04-29 10:27   ` Kevin Brodsky
2020-04-29 15:24     ` Catalin Marinas
2020-04-29 16:46   ` Dave Martin
2020-04-30 10:21     ` Catalin Marinas
2020-05-04 16:40       ` Dave Martin
2020-05-05 18:03   ` Luis Machado
2020-05-12 19:05   ` Luis Machado
2020-05-13 10:48     ` Catalin Marinas
2020-05-13 12:52       ` Luis Machado
2020-05-13 14:11         ` Catalin Marinas
2020-05-13 15:09           ` Luis Machado
2020-05-13 16:45             ` Luis Machado
2020-05-13 17:11               ` Catalin Marinas [this message]
2020-05-18 16:47               ` Dave Martin
2020-05-18 17:12                 ` Luis Machado
2020-05-19 16:10                   ` Catalin Marinas
2020-04-21 14:26 ` [PATCH v3 20/23] fs: Allow copy_mount_options() to access user-space in a single pass Catalin Marinas
2020-04-21 15:29   ` Al Viro
2020-04-21 16:45     ` Catalin Marinas
2020-04-27 16:56   ` Dave Martin
2020-04-28 14:06     ` Catalin Marinas
2020-04-29 10:28       ` Dave Martin
2020-04-28 18:16   ` Kevin Brodsky
2020-04-28 19:40     ` Catalin Marinas
2020-04-29 11:58     ` Catalin Marinas
2020-04-28 19:36   ` Catalin Marinas
2020-04-29 10:26   ` Dave Martin
2020-04-29 13:52     ` Catalin Marinas
2020-05-04 16:40       ` Dave Martin
2020-04-21 14:26 ` [PATCH v3 21/23] arm64: mte: Check the DT memory nodes for MTE support Catalin Marinas
2020-04-24 13:57   ` Catalin Marinas
2020-04-24 16:17     ` Catalin Marinas
2020-04-27 11:14       ` Suzuki K Poulose
2020-04-21 14:26 ` [PATCH v3 22/23] arm64: mte: Kconfig entry Catalin Marinas
2020-04-21 14:26 ` [PATCH v3 23/23] arm64: mte: Add Memory Tagging Extension documentation Catalin Marinas
2020-04-29 16:47   ` Dave Martin
2020-04-30 16:23     ` Catalin Marinas
2020-05-04 16:46       ` Dave Martin
2020-05-11 16:40         ` Catalin Marinas
2020-05-13 15:48           ` Dave Martin
2020-05-14 11:37             ` Catalin Marinas
2020-05-15 10:38               ` Catalin Marinas
2020-05-15 11:14                 ` Szabolcs Nagy
2020-05-15 11:27                   ` Catalin Marinas
2020-05-15 12:04                     ` Szabolcs Nagy
2020-05-15 12:13                       ` Catalin Marinas
2020-05-15 12:53                         ` Szabolcs Nagy
2020-05-18 16:52                           ` Dave Martin
2020-05-18 17:13               ` Catalin Marinas
2020-05-05 10:32   ` Szabolcs Nagy
2020-05-05 17:30     ` Catalin Marinas

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