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From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
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Subject: Re: [PATCH v3 21/36] arm64/mm: Implement map_shadow_stack()
Date: Mon, 31 Jul 2023 23:19:34 +0000	[thread overview]
Message-ID: <e827138f9d8800e3db158831bca88d1ea8b559af.camel@intel.com> (raw)
In-Reply-To: <0a6c90d6-f790-4036-a364-d4761fdd0e95@sirena.org.uk>

On Mon, 2023-07-31 at 18:06 +0100, Mark Brown wrote:
> > Someday when the x86 side is finally upstream I have a manpage for
> > map_shadow_stack. Any differences on the arm side would need to be
> > documented, but I'm not sure why there should be any differences.
> > Like,
> > why not use the same flags? Or have a new flag for token+end marker
> > that x86 can use as well?
> 
> Ah, it wasn't clear to me that this was a question rather than just
> open decisions about the eventual manpage.  Looking again I think
> what
> you're asking about is that I see that at some point in development I
> lost the SHADOW_STACK_SET_TOKEN flag which x86 has.  I suspect that
> was
> a rebasing issue as it wasn't a deliberate decision, there's no
> reason
> we couldn't have that.  Other than that and the fact that we add both
> a
> stack swap token and a top of stack marker I'm not aware of any
> differences.

The thing I was trying to get at was, we have this shared syscall that
means create shadow stack memory and prepopulate it like this flag
says. On x86 we optionally support SHADOW_STACK_SET_TOKEN which means
put a token right at the end of size. So maybe arm should have a
different flag value that includes putting the marker and then the
token, and x86 could match it someday if we get markers too.

It could be a different flag, like SHADOW_STACK_SET_TOKEN_MARKER, or it
could be SHADOW_STACK_SET_MARKER, and callers could pass
(SHADOW_STACK_SET_TOKEN | SHADOW_STACK_SET_MARKER) to get what you have
implemented here. What do you think?

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  reply	other threads:[~2023-07-31 23:19 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-31 13:43 [PATCH v3 00/36] arm64/gcs: Provide support for GCS in userspace Mark Brown
2023-07-31 13:43 ` [PATCH v3 01/36] prctl: arch-agnostic prctl for shadow stack Mark Brown
2023-07-31 13:43 ` [PATCH v3 02/36] arm64: Document boot requirements for Guarded Control Stacks Mark Brown
2023-07-31 13:43 ` [PATCH v3 03/36] arm64/gcs: Document the ABI " Mark Brown
2023-07-31 13:43 ` [PATCH v3 04/36] arm64/sysreg: Add new system registers for GCS Mark Brown
2023-07-31 13:43 ` [PATCH v3 05/36] arm64/sysreg: Add definitions for architected GCS caps Mark Brown
2023-07-31 13:43 ` [PATCH v3 06/36] arm64/gcs: Add manual encodings of GCS instructions Mark Brown
2023-07-31 13:43 ` [PATCH v3 07/36] arm64/gcs: Provide copy_to_user_gcs() Mark Brown
2023-07-31 13:43 ` [PATCH v3 08/36] arm64/cpufeature: Runtime detection of Guarded Control Stack (GCS) Mark Brown
2023-07-31 13:43 ` [PATCH v3 09/36] arm64/mm: Allocate PIE slots for EL0 guarded control stack Mark Brown
2023-07-31 13:43 ` [PATCH v3 10/36] mm: Define VM_SHADOW_STACK for arm64 when we support GCS Mark Brown
2023-08-01 16:53   ` Mike Rapoport
2023-07-31 13:43 ` [PATCH v3 11/36] arm64/mm: Map pages for guarded control stack Mark Brown
2023-08-01 17:02   ` Mike Rapoport
2023-08-01 19:05     ` Mark Brown
2023-07-31 13:43 ` [PATCH v3 12/36] KVM: arm64: Manage GCS registers for guests Mark Brown
2023-07-31 13:43 ` [PATCH v3 13/36] arm64/gcs: Allow GCS usage at EL0 and EL1 Mark Brown
2023-07-31 13:43 ` [PATCH v3 14/36] arm64/idreg: Add overrride for GCS Mark Brown
2023-07-31 13:43 ` [PATCH v3 15/36] arm64/hwcap: Add hwcap " Mark Brown
2023-07-31 13:43 ` [PATCH v3 16/36] arm64/traps: Handle GCS exceptions Mark Brown
2023-07-31 13:43 ` [PATCH v3 17/36] arm64/mm: Handle GCS data aborts Mark Brown
2023-07-31 13:43 ` [PATCH v3 18/36] arm64/gcs: Context switch GCS state for EL0 Mark Brown
2023-07-31 13:43 ` [PATCH v3 19/36] arm64/gcs: Allocate a new GCS for threads with GCS enabled Mark Brown
2023-07-31 13:43 ` [PATCH v3 20/36] arm64/gcs: Implement shadow stack prctl() interface Mark Brown
2023-07-31 13:43 ` [PATCH v3 21/36] arm64/mm: Implement map_shadow_stack() Mark Brown
2023-07-31 15:56   ` Edgecombe, Rick P
2023-07-31 17:06     ` Mark Brown
2023-07-31 23:19       ` Edgecombe, Rick P [this message]
2023-08-01 14:01         ` Mark Brown
2023-08-01 17:07           ` Edgecombe, Rick P
2023-08-01 17:28             ` Mike Rapoport
2023-08-01 18:03               ` Mark Brown
2023-08-01 17:57             ` Mark Brown
2023-08-01 20:57               ` Edgecombe, Rick P
2023-08-02 16:27                 ` Mark Brown
2023-08-04 13:38                   ` Mark Brown
2023-08-04 16:43                     ` Edgecombe, Rick P
2023-08-04 17:10                       ` Mark Brown
2023-08-07 10:20   ` Szabolcs Nagy
2023-08-07 13:00     ` Mark Brown
2023-08-08  8:21       ` Szabolcs Nagy
2023-08-08 20:42         ` Mark Brown
2023-07-31 13:43 ` [PATCH v3 22/36] arm64/signal: Set up and restore the GCS context for signal handlers Mark Brown
2023-07-31 13:43 ` [PATCH v3 23/36] arm64/signal: Expose GCS state in signal frames Mark Brown
2023-07-31 13:43 ` [PATCH v3 24/36] arm64/ptrace: Expose GCS via ptrace and core files Mark Brown
2023-07-31 13:43 ` [PATCH v3 25/36] arm64: Add Kconfig for Guarded Control Stack (GCS) Mark Brown
2023-07-31 13:43 ` [PATCH v3 26/36] kselftest/arm64: Verify the GCS hwcap Mark Brown
2023-07-31 13:43 ` [PATCH v3 27/36] kselftest/arm64: Add GCS as a detected feature in the signal tests Mark Brown
2023-07-31 13:43 ` [PATCH v3 28/36] kselftest/arm64: Add framework support for GCS to signal handling tests Mark Brown
2023-07-31 13:43 ` [PATCH v3 29/36] kselftest/arm64: Allow signals tests to specify an expected si_code Mark Brown
2023-07-31 13:43 ` [PATCH v3 30/36] kselftest/arm64: Always run signals tests with GCS enabled Mark Brown
2023-07-31 13:43 ` [PATCH v3 31/36] kselftest/arm64: Add very basic GCS test program Mark Brown
2023-07-31 13:43 ` [PATCH v3 32/36] kselftest/arm64: Add a GCS test program built with the system libc Mark Brown
2023-07-31 13:43 ` [PATCH v3 33/36] kselftest/arm64: Add test coverage for GCS mode locking Mark Brown
2023-07-31 13:43 ` [PATCH v3 34/36] selftests/arm64: Add GCS signal tests Mark Brown
2023-07-31 13:43 ` [PATCH v3 35/36] kselftest/arm64: Add a GCS stress test Mark Brown
2023-07-31 13:43 ` [PATCH v3 36/36] kselftest/arm64: Enable GCS for the FP stress tests Mark Brown
2023-08-01 14:13 ` [PATCH v3 00/36] arm64/gcs: Provide support for GCS in userspace Will Deacon
2023-08-01 15:09   ` Mark Brown
2023-08-08 10:27     ` Szabolcs Nagy
2023-08-08 13:38     ` Will Deacon
2023-08-08 20:25       ` Mark Brown
2023-08-10  9:40         ` Will Deacon
2023-08-10 16:05           ` Mark Brown

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