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

[Jason Yan]

在 2020/3/5 5:53, Scott Wood 写道:
> On Thu, 2020-02-06 at 10:58 +0800, Jason Yan wrote:
>> The original kernel still exists in the memory, clear it now.
>>
>> Signed-off-by: Jason Yan <yanaijie at huawei.com>
>> Cc: Scott Wood <oss at buserror.net>
>> Cc: Diana Craciun <diana.craciun at nxp.com>
>> Cc: Michael Ellerman <mpe at ellerman.id.au>
>> Cc: Christophe Leroy <christophe.leroy at c-s.fr>
>> Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
>> Cc: Paul Mackerras <paulus at samba.org>
>> Cc: Nicholas Piggin <npiggin at gmail.com>
>> Cc: Kees Cook <keescook at chromium.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;
>> +	}
> 
> What if you're here because kexec set __run_at_load (or
> CONFIG_RELOCATABLE_TEST is enabled), not because kaslr happened?
> 

Nothing will happen because kaslr_late_init() only clears memory when
kernstart_virt_addr is not KERNELBASE. When __run_at_load is set then
KASLR will not take effect.

> -Scott
> 
> 
> 
> .
>