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From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "broonie@kernel.org" <broonie@kernel.org>
Cc: "dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
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Subject: Re: [PATCH RFT v9 4/8] fork: Add shadow stack support to clone3()
Date: Wed, 2 Oct 2024 21:25:05 +0000	[thread overview]
Message-ID: <b81b2994e286259a78f3d20660469e88a8b08c31.camel@intel.com> (raw)
In-Reply-To: <Zv20luC6us-LEMqN@finisterre.sirena.org.uk>

On Wed, 2024-10-02 at 22:01 +0100, Mark Brown wrote:
> BTW it's probably also worth noting that at least on arm64 (perhaps x86
> is different here?) the shadow stack of a thread that exited won't have
> a token placed on it so it won't be possible to use it with clone3() at
> all unless another token is written.  To get a shadow stack you could
> use with clone3() you'd either need to allocate a new one, pivot away
> from one that's currently in use or enable shadow stack writes and place
> a token.

Hmm, yea. I didn't have a specific idea in mind. But yea, you would have to
switch to something in order to leave a token.

If you enabled WRSS (or similar) you might be able to reuse shadow stacks in
some kind of useful way, but in that case you would probably WRSS the token to
the end of the shadow stack and the start+size would fit better.

  reply	other threads:[~2024-10-02 21:25 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-19 19:24 [PATCH RFT v9 0/8] fork: Support shadow stacks in clone3() Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 1/8] Documentation: userspace-api: Add shadow stack API documentation Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 2/8] selftests: Provide helper header for shadow stack testing Mark Brown
2024-08-20 21:36   ` Edgecombe, Rick P
2024-08-19 19:24 ` [PATCH RFT v9 3/8] mm: Introduce ARCH_HAS_USER_SHADOW_STACK Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 4/8] fork: Add shadow stack support to clone3() Mark Brown
2024-08-20 21:36   ` Edgecombe, Rick P
2024-08-20 23:34     ` Mark Brown
2024-08-20 23:57       ` Edgecombe, Rick P
2024-08-21  0:19         ` Mark Brown
2024-08-21  1:45           ` Edgecombe, Rick P
2024-08-21 12:45             ` Mark Brown
2024-08-21 15:54               ` Edgecombe, Rick P
2024-08-21 17:23                 ` Mark Brown
2024-08-21 18:05                   ` Catalin Marinas
2024-09-27  8:50                   ` Christian Brauner
2024-09-27 15:21                     ` Edgecombe, Rick P
2024-10-01 15:12                       ` Christian Brauner
2024-10-01 17:33                         ` Mark Brown
2024-10-01 23:03                           ` Edgecombe, Rick P
2024-10-02 13:42                             ` Mark Brown
2024-10-02 21:01                               ` Mark Brown
2024-10-02 21:25                                 ` Edgecombe, Rick P [this message]
2024-10-03 16:05                         ` Yury Khrustalev
2024-08-19 19:24 ` [PATCH RFT v9 5/8] selftests/clone3: Remove redundant flushes of output streams Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 6/8] selftests/clone3: Factor more of main loop into test_clone3() Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 7/8] selftests/clone3: Allow tests to flag if -E2BIG is a valid error code Mark Brown
2024-08-19 19:24 ` [PATCH RFT v9 8/8] selftests/clone3: Test shadow stack support Mark Brown

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