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Subject: Re: [PATCH stable 4.4] powerpc/lib: fix book3s/32 boot failure due to
 code patching
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, erhard_f@mailbox.org,
        Michael Neuling <mikey@neuling.org>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
References: <71dbc8bdad5da9f6cb0446535fb2a29c68fccf80.1557926850.git.christophe.leroy@c-s.fr>
 <20190515141604.GB8999@kroah.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <f9ca9827-6394-0904-2559-9da18171fb32@c-s.fr>
Date:   Wed, 15 May 2019 17:13:29 +0200
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Le 15/05/2019 à 16:16, Greg KH a écrit :
> On Wed, May 15, 2019 at 01:30:42PM +0000, Christophe Leroy wrote:
>> [Backport of upstream commit b45ba4a51cde29b2939365ef0c07ad34c8321789]
>>
>> On powerpc32, patch_instruction() is called by apply_feature_fixups()
>> which is called from early_init()
>>
>> There is the following note in front of early_init():
>>   * Note that the kernel may be running at an address which is different
>>   * from the address that it was linked at, so we must use RELOC/PTRRELOC
>>   * to access static data (including strings).  -- paulus
>>
>> Therefore init_mem_is_free must be accessed with PTRRELOC()
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203597
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>
>> ---
>> Can't apply the upstream commit as such due to several other unrelated stuff
>> like for instance STRICT_KERNEL_RWX which are missing.
>> So instead, using same approach as for commit 252eb55816a6f69ef9464cad303cdb3326cdc61d
>>
>> Removed the Fixes: tag as I don't know yet the commit Id of the fixed commit on 4.4 branch.
>> ---
>>   arch/powerpc/lib/code-patching.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Now added, thanks.
> 

Thanks,

However you took the commit log from the upstream commit, which doesn't 
corresponds exactly to the change being done here and described in the 
backport patch

Christophe