From: Catalin Marinas <catalin.marinas@arm.com>
To: Kristina Martsenko <kristina.martsenko@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Mark Rutland <mark.rutland@arm.com>,
Mark Brown <broonie@kernel.org>,
Luis Machado <luis.machado@arm.com>,
Vladimir Murzin <vladimir.murzin@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/10] arm64: mops: handle single stepping after MOPS exception
Date: Fri, 17 Mar 2023 16:02:06 +0000 [thread overview]
Message-ID: <ZBSO/sWK1IGkoOxj@arm.com> (raw)
In-Reply-To: <20230216160012.272345-9-kristina.martsenko@arm.com>
On Thu, Feb 16, 2023 at 04:00:10PM +0000, Kristina Martsenko wrote:
> When a MOPS main or epilogue instruction is being executed, the task may
> get scheduled on a different CPU and restart execution from the prologue
> instruction. If the main or epilogue instruction is being single stepped
> then it makes sense to finish the step and take the step exception
> before starting to execute the next (prologue) instruction. So
> fast-forward the single step state machine when taking a MOPS exception.
>
> This means that if a main or epilogue instruction is single stepped with
> ptrace, the debugger will sometimes observe the PC moving back to the
> prologue instruction. (As already mentioned, this should be rare as it
> only happens when the task is scheduled to another CPU during the step.)
>
> This also ensures that perf breakpoints count prologue instructions
> consistently (i.e. every time they are executed), rather than skipping
> them when there also happens to be a breakpoint on a main or epilogue
> instruction.
>
> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2023-03-17 16:02 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 16:00 [PATCH 00/10] arm64: support Armv8.8 memcpy instructions in userspace Kristina Martsenko
2023-02-16 16:00 ` [PATCH 01/10] KVM: arm64: initialize HCRX_EL2 Kristina Martsenko
2023-03-17 14:25 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 02/10] arm64: cpufeature: detect FEAT_HCX Kristina Martsenko
2023-03-17 14:25 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 03/10] KVM: arm64: switch HCRX_EL2 between host and guest Kristina Martsenko
2023-02-16 16:20 ` Mark Brown
2023-02-22 18:36 ` Kristina Martsenko
2023-02-16 16:35 ` Marc Zyngier
2023-02-22 18:42 ` Kristina Martsenko
2023-02-16 16:00 ` [PATCH 04/10] arm64: mops: document boot requirements for MOPS Kristina Martsenko
2023-03-17 15:07 ` Catalin Marinas
2023-03-24 1:00 ` Kristina Martsenko
2023-04-04 10:50 ` Catalin Marinas
2023-04-11 16:57 ` Kristina Martsenko
2023-02-16 16:00 ` [PATCH 05/10] arm64: mops: don't disable host MOPS instructions from EL2 Kristina Martsenko
2023-03-17 15:07 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 06/10] KVM: arm64: hide MOPS from guests Kristina Martsenko
2023-03-17 15:09 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 07/10] arm64: mops: handle MOPS exceptions Kristina Martsenko
2023-03-17 15:45 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 08/10] arm64: mops: handle single stepping after MOPS exception Kristina Martsenko
2023-03-17 16:02 ` Catalin Marinas [this message]
2023-02-16 16:00 ` [PATCH 09/10] arm64: mops: detect and enable FEAT_MOPS Kristina Martsenko
2023-02-16 16:22 ` Mark Brown
2023-03-17 16:03 ` Catalin Marinas
2023-02-16 16:00 ` [PATCH 10/10] arm64: mops: allow disabling MOPS from the kernel command line Kristina Martsenko
2023-03-17 16:04 ` Catalin Marinas
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