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Date:   Mon, 21 Dec 2020 10:31:30 -0600
From:   Segher Boessenkool <segher@kernel.crashing.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Xiaoming Ni <nixiaoming@huawei.com>, linux-kernel@vger.kernel.org,
        benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org,
        linuxppc-dev@lists.ozlabs.org, yanaijie@huawei.com,
        npiggin@gmail.com, ravi.bangoria@linux.ibm.com, mikey@neuling.org,
        aneesh.kumar@linux.ibm.com, haren@linux.ibm.com, wangle6@huawei.com
Subject: Re: [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs()
Message-ID: <20201221163130.GZ2672@gate.crashing.org>
References: <20201221032758.12143-1-nixiaoming@huawei.com> <2279fc96-1f10-0c3f-64d9-734f18758620@csgroup.eu>
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On Mon, Dec 21, 2020 at 04:17:21PM +0100, Christophe Leroy wrote:
> Le 21/12/2020 ? 04:27, Xiaoming Ni a ?crit?:
> >Since the commit 2b0e86cc5de6 ("powerpc/fsl_booke/32: implement KASLR
> >infrastructure"), the powerpc system is ready to support KASLR.
> >To reduces the risk of invalidating address randomization, don't print the
> >EIP/LR hex values in dump_stack() and show_regs().

> I think your change is not enough to hide EIP address, see below a dump 
> with you patch, you get "Faulting instruction address: 0xc03a0c14"

As far as I can see the patch does nothing to the GPR printout.  Often
GPRs contain code addresses.  As one example, the LR is moved via a GPR
(often GPR0, but not always) for storing on the stack.

So this needs more work.


Segher