From: Kevin Hilman <khilman@linaro.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <Will.Deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel\@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linaro-kernel\@lists.linaro.org"
<linaro-kernel@lists.linaro.org>,
"khilman\@linaro.org" <khilman@linaro.org>
Subject: Re: [PATCH 1/3] arm64: adjust el0_sync so that a function can be called
Date: Mon, 05 May 2014 15:44:30 -0700 [thread overview]
Message-ID: <7hsionc0c1.fsf@paris.lan> (raw)
In-Reply-To: <20140429094211.GC17007@arm.com> (Catalin Marinas's message of "Tue, 29 Apr 2014 10:42:11 +0100")
[+ Mark R. since we looked at this together a little at ELC]
Catalin Marinas <catalin.marinas@arm.com> writes:
> On Sun, Apr 27, 2014 at 08:44:12PM +0100, Larry Bassel wrote:
>> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
>> index 39ac630..eda7755 100644
>> --- a/arch/arm64/kernel/entry.S
>> +++ b/arch/arm64/kernel/entry.S
> [...]
>> @@ -421,28 +421,30 @@ el0_da:
>> /*
>> * Data abort handling
>> */
>> - mrs x0, far_el1
>> - bic x0, x0, #(0xff << 56)
>> disable_step x1
>> isb
>> enable_dbg
>> // enable interrupts before calling the main handler
>> enable_irq
>> + mrs x0, far_el1
>> + bic x0, x0, #(0xff << 56)
>> mov x1, x25
>> mov x2, sp
>> b do_mem_abort
>
> Reading the far_el1 after enable_dbg and enable_irq is racy, we can no
> longer guarantee its value in the original data abort context.
Catalin, can you confirm x26 would be a safe place to stash far_el1 and
then restore it after ct_user_exit. Something like this (which seems to
work for me):
el0_da:
/* * Data abort handling */
mrs x26, far_el1
disable_step x1
isb
enable_dbg
// enable interrupts before calling the main handler
enable_irq
ct_user_exit
mov x0, x26
bic x0, x0, #(0xff << 56)
mov x1, x25
mov x2, sp
adr lr, ret_from_exception
b do_mem_abort
Kevin
next prev parent reply other threads:[~2014-05-05 22:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-27 19:44 [PATCH 0/3] context tracker support for arm64 Larry Bassel
2014-04-27 19:44 ` [PATCH 1/3] arm64: adjust el0_sync so that a function can be called Larry Bassel
2014-04-29 9:42 ` Catalin Marinas
2014-05-05 22:44 ` Kevin Hilman [this message]
2014-04-27 19:44 ` [PATCH 2/3] arm64: add support for context tracking Larry Bassel
2014-04-27 19:44 ` [PATCH 3/3] arm64: enable " Larry Bassel
2014-04-29 9:43 ` Catalin Marinas
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