From: Mark Rutland <mark.rutland@arm.com>
To: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, arnd@arndb.de,
mathieu.desnoyers@efficios.com, peterz@infradead.org,
paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com,
catalin.marinas@arm.com, peter.maydell@linaro.org
Subject: Re: [PATCH 1/3] arm64: rseq: Implement backend rseq calls and select HAVE_RSEQ
Date: Tue, 26 Jun 2018 11:31:14 +0100 [thread overview]
Message-ID: <20180626103114.ddu62cccupjdo2ia@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <1529949285-11013-2-git-send-email-will.deacon@arm.com>
On Mon, Jun 25, 2018 at 06:54:43PM +0100, Will Deacon wrote:
> /*
> * Please add new compat syscalls above this comment and update
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 28ad8799406f..1eda9e1a1f4a 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -904,6 +904,7 @@ ENDPROC(el0_error)
> ret_fast_syscall:
> disable_daif
> str x0, [sp, #S_X0] // returned x0
> +#ifndef CONFIG_DEBUG_RSEQ
> ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing
> and x2, x1, #_TIF_SYSCALL_WORK
> cbnz x2, ret_fast_syscall_trace
> @@ -911,6 +912,7 @@ ret_fast_syscall:
> cbnz x2, work_pending
> enable_step_tsk x1, x2
> kernel_exit 0
> +#endif
> ret_fast_syscall_trace:
> enable_daif
> b __sys_trace_return_skipped // we already saved x0
I *think* this is ok, since we re-check the TIF bits in
syscall_trace_exit().
This does mean that we'd now always call audit_syscall_exit(),
regardless of TIF_AUDIT, but there are already cases when we call that
with TIF_AUDIT clear, so I think if that's a problem it's a latent bug.
Likewise for audit_syscall_entry().
It seems we're in the same boat as other architectures there,
regardless.
FWIW, for the entry bits:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
next prev parent reply other threads:[~2018-06-26 10:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-25 17:54 [PATCH 0/3] Support rseq on arm64 Will Deacon
2018-06-25 17:54 ` [PATCH 1/3] arm64: rseq: Implement backend rseq calls and select HAVE_RSEQ Will Deacon
2018-06-26 10:31 ` Mark Rutland [this message]
2018-06-25 17:54 ` [PATCH 2/3] asm-generic: unistd.h: Wire up sys_rseq Will Deacon
2018-06-25 17:54 ` [PATCH 3/3] rseq/selftests: Add support for arm64 Will Deacon
2018-06-25 18:10 ` Mathieu Desnoyers
2018-06-26 15:14 ` Will Deacon
2018-06-26 16:11 ` Mathieu Desnoyers
2018-06-28 16:47 ` Will Deacon
2018-06-28 20:50 ` Mathieu Desnoyers
2018-07-02 16:49 ` Will Deacon
2018-07-02 17:47 ` Mathieu Desnoyers
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