linux-kernel - Re: [PATCH v3 5/6] powerpc/fsl_booke/64: clear the original kernel if randomized

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Date:   Wed, 26 Feb 2020 10:44:09 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     Christophe Leroy <christophe.leroy@....fr>, <mpe@...erman.id.au>,
        <linuxppc-dev@...ts.ozlabs.org>, <diana.craciun@....com>,
        <benh@...nel.crashing.org>, <paulus@...ba.org>,
        <npiggin@...il.com>, <keescook@...omium.org>,
        <kernel-hardening@...ts.openwall.com>, <oss@...error.net>
CC:     <linux-kernel@...r.kernel.org>, <zhaohongjiang@...wei.com>
Subject: Re: [PATCH v3 5/6] powerpc/fsl_booke/64: clear the original kernel if
 randomized



在 2020/2/20 21:49, Christophe Leroy 写道:
> 
> 
> Le 06/02/2020 à 03:58, Jason Yan a écrit :
>> The original kernel still exists in the memory, clear it now.
> 
> No such problem with PPC32 ? Or is that common ?
> 

PPC32 did this in relocate_init() in fsl_booke.c because PPC32 will not 
reach kaslr_early_init for the second pass after relocation.

Thanks,
Jason

> Christophe
> 
>>
>> Signed-off-by: Jason Yan <yanaijie@...wei.com>
>> Cc: Scott Wood <oss@...error.net>
>> Cc: Diana Craciun <diana.craciun@....com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Christophe Leroy <christophe.leroy@....fr>
>> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> Cc: Paul Mackerras <paulus@...ba.org>
>> Cc: Nicholas Piggin <npiggin@...il.com>
>> Cc: Kees Cook <keescook@...omium.org>
>> ---
>>   arch/powerpc/mm/nohash/kaslr_booke.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c 
>> b/arch/powerpc/mm/nohash/kaslr_booke.c
>> index c6f5c1db1394..ed1277059368 100644
>> --- a/arch/powerpc/mm/nohash/kaslr_booke.c
>> +++ b/arch/powerpc/mm/nohash/kaslr_booke.c
>> @@ -378,8 +378,10 @@ notrace void __init kaslr_early_init(void 
>> *dt_ptr, phys_addr_t size)
>>       unsigned int *__kaslr_offset = (unsigned int *)(KERNELBASE + 0x58);
>>       unsigned int *__run_at_load = (unsigned int *)(KERNELBASE + 0x5c);
>> -    if (*__run_at_load == 1)
>> +    if (*__run_at_load == 1) {
>> +        kaslr_late_init();
>>           return;
>> +    }
>>       /* Setup flat device-tree pointer */
>>       initial_boot_params = dt_ptr;
>>
> 
> .