From: Mark Rutland <mark.rutland@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: keescook@chromium.org, maz@kernel.org, robin.murphy@arm.com,
broonie@kernel.org, james.morse@arm.com,
julien.thierry.kdev@gmail.com, catalin.marinas@arm.com,
labbott@redhat.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org, alex.popov@linux.com
Subject: Re: [PATCH 01/17] arm64: entry: mark all entry code as notrace
Date: Mon, 13 Jan 2020 15:44:04 +0000 [thread overview]
Message-ID: <20200113154259.GA17782@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <6ac3017e-07cb-8ef4-c2e9-22a6fc8d8e24@arm.com>
On Thu, Jan 09, 2020 at 10:51:10AM +0530, Anshuman Khandual wrote:
>
>
> On 01/09/2020 12:26 AM, Mark Rutland wrote:
> > Almost all functions in entry-common.c are marked notrace, with
> > el1_undef and el1_inv being the only exceptions. We appear to have done
> > this on the assumption that there were no exception registers that we
> > needed to snapshot, and thus it was safe to run trace code that might
> > result in further exceptions and clobber those registers.
> >
> > However, until we inherit the DAIF flags, our irq flag tracing is stale,
> > and this discrepancy could set off warnings in some configurations.
>
> Could you give some example scenarios when this might happen ?
With CONFIG_DEBUG_LOCKDEP, any locked-instrumented function which calls
check_flags() would trigger this. So if your trace function does any
sort of lock manipulation it's liable to set this off.
I'll amend the above:
| However, until we inherit the DAIF flags, our irq flag tracing is
| stale, and this discrepancy could set off warnings in some
| configurations (e.g. with CONFIG_DEBUG_LOCKDEP).
I also hope that flag checking is performed more generally in future,
since at the moment it's only strictly performed for locking operations.
Thanks,
Mark.
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next prev parent reply other threads:[~2020-01-13 15:44 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-08 18:56 [PATCH 00/17] arm64: entry deasmification and cleanup Mark Rutland
2020-01-08 18:56 ` [PATCH 01/17] arm64: entry: mark all entry code as notrace Mark Rutland
2020-01-09 5:21 ` Anshuman Khandual
2020-01-13 15:44 ` Mark Rutland [this message]
2020-01-08 18:56 ` [PATCH 02/17] arm64: entry: cleanup el0 svc handler naming Mark Rutland
2020-01-09 5:33 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 03/17] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2020-01-09 5:36 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 04/17] arm64: entry: move preempt logic to C Mark Rutland
2020-01-09 6:43 ` Anshuman Khandual
2020-01-09 12:22 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 05/17] arm64: entry: add a call_on_stack helper Mark Rutland
2020-01-09 8:00 ` Anshuman Khandual
2020-01-14 18:24 ` Mark Rutland
2020-01-09 14:30 ` Laura Abbott
2020-01-09 14:46 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 06/17] arm64: entry: convert irq entry to C Mark Rutland
2020-01-08 18:56 ` [PATCH 07/17] arm64: entry: convert error " Mark Rutland
2020-01-09 9:12 ` Anshuman Khandual
2020-01-09 12:49 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 08/17] arm64: entry: Split el0_sync_compat from el0_sync Mark Rutland
2020-01-09 9:50 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 09/17] arm64: entry: organise handler stubs consistently Mark Rutland
2020-01-09 10:01 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 10/17] arm64: entry: consolidate EL1 return paths Mark Rutland
2020-01-10 3:39 ` Anshuman Khandual
2020-01-10 16:02 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 11/17] stackleak: allow C to call stackleak_erase() Mark Rutland
2020-01-10 3:45 ` Anshuman Khandual
2020-01-10 16:07 ` Mark Rutland
2020-01-27 23:00 ` Kees Cook
2020-01-08 18:56 ` [PATCH 12/17] arm64: debug-monitors: refactor MDSCR manipulation Mark Rutland
2020-01-10 4:35 ` Anshuman Khandual
2020-01-10 16:09 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 13/17] arm64: entry: move common el0 entry/return work to C Mark Rutland
2020-01-09 15:19 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 14/17] arm64: entry: move NO_SYSCALL setup " Mark Rutland
2020-01-10 5:37 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 15/17] arm64: entry: move ARM64_ERRATUM_845719 workaround " Mark Rutland
2020-01-08 18:56 ` [PATCH 16/17] arm64: entry: move ARM64_ERRATUM_1418040 " Mark Rutland
2020-01-08 18:56 ` [PATCH 17/17] arm64: entry: cleanup sp_el0 manipulation Mark Rutland
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