From: Marc Zyngier <maz@kernel.org>
To: wangrongwei <rongwei.wang@linux.alibaba.com>
Cc: vkoul@kernel.org, gshan@redhat.com, Anson.Huang@nxp.com,
geert+renesas@glider.be, catalin.marinas@arm.com,
masahiroy@kernel.org, linux-kernel@vger.kernel.org,
krzk@kernel.org, bjorn.andersson@linaro.org, michael@walle.cc,
olof@lixom.net, shawnguo@kernel.org, vincenzo.frascino@arm.com,
Will Deacon <will@kernel.org>,
ardb@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] arm64:msr: Add MSR driver
Date: Tue, 01 Dec 2020 15:37:26 +0000 [thread overview]
Message-ID: <7e9ae04f3394a85aa3b8fe8947a44009@kernel.org> (raw)
In-Reply-To: <6FA68A07-F718-46F5-81B4-586A5ED3E479@linux.alibaba.com>
On 2020-12-01 14:25, wangrongwei wrote:
>> 2020年12月1日 下午4:12，Marc Zyngier <maz@kernel.org> 写道：
>>
>> On 2020-12-01 03:09, wangrongwei wrote:
>>> Hi
>>> We have validate this driver in vm and physical machine, and works
>>> fine.
>>
>> But what does "work fine" mean? None of these system registers are
>> supposed
>> to be accessible from userspace, so please explain *what* you are
>> trying to
>> do with this, other that introducing security holes and general system
>> instability?
> I think I know what you mean. Do you want me to describe how we
> achieved it?
> In x86, the different registers can be accessed directly using the
> rdmsr and wrmsr instructions, but in ARM, since these two instructions
> are missing, so we modify the code segment during runtime, similar to
> the principle of static_key.
[...]
These are implementation details, none of which answer my question:
What makes you think this is a good idea? I cannot see any legitimate
reason for userspace to ever access privileged system registers, and
the fact that x86 has such feature isn't a good justification.
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2020-12-01 15:47 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 17:48 [PATCH 0/3] arm64:msr: Add MSR driver Rongwei Wang
2020-11-30 17:48 ` [PATCH 1/3] arm64:insn: Export symbols for MSR ARM driver Rongwei Wang
2020-11-30 17:48 ` [PATCH 2/3] arm64:msr: Introduce " Rongwei Wang
2020-11-30 17:48 ` [PATCH 3/3] arm64:msr: Enable " Rongwei Wang
2020-11-30 17:57 ` [PATCH 0/3] arm64:msr: Add MSR driver Will Deacon
2020-12-01 2:55 ` wangrongwei
2020-12-01 5:44 ` wangrongwei
2020-11-30 18:05 ` Marc Zyngier
2020-11-30 18:20 ` Randy Dunlap
2020-12-01 3:09 ` wangrongwei
2020-12-01 8:12 ` Marc Zyngier
2020-12-01 14:25 ` wangrongwei
2020-12-01 15:37 ` Marc Zyngier [this message]
2020-12-03 5:45 ` Rongwei Wang
2020-12-03 8:35 ` Marc Zyngier
2020-12-03 11:25 ` Rongwei Wang
2020-12-03 11:45 ` Marc Zyngier
2020-12-03 12:22 ` Rongwei Wang
2020-12-03 11:50 ` Mark Rutland
2020-11-30 19:03 ` Borislav Petkov
2020-12-01 3:44 ` wangrongwei
2020-12-01 11:26 ` Borislav Petkov
2020-12-01 14:33 ` wangrongwei
2020-12-01 14:54 ` Borislav Petkov
2020-12-01 15:17 ` Rongwei Wang
2020-12-01 15:25 ` Borislav Petkov
2020-12-03 2:09 ` Rongwei Wang
2020-12-01 15:26 ` Ard Biesheuvel
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