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From: Mark Brown <broonie@kernel.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v2 2/3] efi: arm64: Wire up BTI annotation in memory attributes table
Date: Mon, 20 Feb 2023 15:53:26 +0000	[thread overview]
Message-ID: <Y/OXdpfcsoPxgHdq@sirena.org.uk> (raw)
In-Reply-To: <CAMj1kXG5iG=ok_nWnt7Tj5-Evwen4VvOQoNpVHh5mPU2mbCDWQ@mail.gmail.com>

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On Wed, Feb 08, 2023 at 03:36:40PM +0100, Ard Biesheuvel wrote:

> OTOH, what is the penalty for setting the GP attribute and using the
> translation table on a core that does not implement BTI?

The concern with doing that for Linux was what would happen if someone
implemented a system with mixed BTI/no BTI support and then a task got
preempted and moved between the two, you might end up with PSTATE.BTYPE
incorrectly set and trigger a spurious fault.  That shouldn't be an
issue for EFI runtime services.

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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v2 2/3] efi: arm64: Wire up BTI annotation in memory attributes table
Date: Mon, 20 Feb 2023 15:53:26 +0000	[thread overview]
Message-ID: <Y/OXdpfcsoPxgHdq@sirena.org.uk> (raw)
In-Reply-To: <CAMj1kXG5iG=ok_nWnt7Tj5-Evwen4VvOQoNpVHh5mPU2mbCDWQ@mail.gmail.com>


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On Wed, Feb 08, 2023 at 03:36:40PM +0100, Ard Biesheuvel wrote:

> OTOH, what is the penalty for setting the GP attribute and using the
> translation table on a core that does not implement BTI?

The concern with doing that for Linux was what would happen if someone
implemented a system with mixed BTI/no BTI support and then a task got
preempted and moved between the two, you might end up with PSTATE.BTYPE
incorrectly set and trigger a spurious fault.  That shouldn't be an
issue for EFI runtime services.

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2023-02-20 15:54 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-06 12:49 [PATCH v2 0/3] efi: Enable BTI for EFI runtimes services Ard Biesheuvel
2023-02-06 12:49 ` Ard Biesheuvel
2023-02-06 12:49 ` [PATCH v2 1/3] efi: Discover BTI support in runtime services regions Ard Biesheuvel
2023-02-06 12:49   ` Ard Biesheuvel
2023-02-06 12:49 ` [PATCH v2 2/3] efi: arm64: Wire up BTI annotation in memory attributes table Ard Biesheuvel
2023-02-06 12:49   ` Ard Biesheuvel
2023-02-08 13:00   ` Will Deacon
2023-02-08 13:00     ` Will Deacon
2023-02-08 13:03     ` Ard Biesheuvel
2023-02-08 13:03       ` Ard Biesheuvel
2023-02-08 14:25       ` Mark Rutland
2023-02-08 14:25         ` Mark Rutland
2023-02-08 14:36         ` Ard Biesheuvel
2023-02-08 14:36           ` Ard Biesheuvel
2023-02-09 14:21           ` Ard Biesheuvel
2023-02-09 14:21             ` Ard Biesheuvel
2023-02-09 15:13             ` Mark Rutland
2023-02-09 15:13               ` Mark Rutland
2023-02-09 15:48             ` Will Deacon
2023-02-09 15:48               ` Will Deacon
2023-02-20 15:53           ` Mark Brown [this message]
2023-02-20 15:53             ` Mark Brown
2023-02-20 16:46             ` Ard Biesheuvel
2023-02-20 16:46               ` Ard Biesheuvel
2023-02-06 12:49 ` [PATCH v2 3/3] efi: x86: Wire up IBT " Ard Biesheuvel
2023-02-06 12:49   ` Ard Biesheuvel
2023-02-08 15:17   ` Dave Hansen
2023-02-08 15:17     ` Dave Hansen
2023-02-08 20:14     ` Peter Zijlstra
2023-02-08 20:14       ` Peter Zijlstra
2023-02-08 20:55       ` Mark Rutland
2023-02-08 20:55         ` Mark Rutland
2023-02-09 16:13         ` Kees Cook
2023-02-09 16:13           ` Kees Cook
2023-02-09 16:23           ` Ard Biesheuvel
2023-02-09 16:23             ` Ard Biesheuvel
2023-02-09 16:27             ` Dave Hansen
2023-02-09 16:27               ` Dave Hansen
2023-02-09 16:37             ` Kees Cook
2023-02-09 16:37               ` Kees Cook
2023-02-08 17:30   ` Peter Zijlstra
2023-02-08 17:30     ` Peter Zijlstra
2023-02-08 12:35 ` [PATCH v2 0/3] efi: Enable BTI for EFI runtimes services Ard Biesheuvel
2023-02-08 12:35   ` Ard Biesheuvel

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