linux-kernel - Re: [PATCH stable 4.9] powerpc/lib: fix book3s/32 boot failure due to code patching

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Date:   Wed, 15 May 2019 14:35:36 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, erhard_f@...lbox.org,
        Michael Neuling <mikey@...ling.org>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH stable 4.9] powerpc/lib: fix book3s/32 boot failure due to
 code patching



Le 15/05/2019 à 10:29, Greg KH a écrit :
> On Wed, May 15, 2019 at 06:40:47AM +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()
>>
>> Fixes: 1c38a84d4586 ("powerpc: Avoid code patching freed init sections")
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203597
>> Signed-off-by: Christophe Leroy <christophe.leroy@....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
> 
> Now queued up, thanks.
> 

Should go to 4.4 as well since the commit it fixes is now queued for 4.4 
([PATCH 4.4 056/266] powerpc: Avoid code patching freed init sections)

Christophe