bootx_init.c:88: undefined reference to `__stack_chk_fail_local'

[Christophe LEROY]

Le 10/01/2017 à 03:11, Christian Kujau a écrit :
> On Wed, 4 Jan 2017, Christian Kujau wrote:
>> So, would the following be sufficient? It compiles, but I haven't had a
>> chance to boot yet.
>>
>
> So, with -fno-stack-protector my GCC 4.9.2 compiles with
> CC_STACKPROTECTOR_STRONG=y but panics during boot:
>
>
>
> Maybe ppc32 is not supposed to be built with CC_STACKPROTECTOR ?

Indeed, the latest versions of GCC don't use anymore the global variable 
__stack_chk_guard as canary value, but a value stored at -0x7008(r2). 
This is not compatible with the current implementation of  the kernel 
with uses r2 as a pointeur to current task struct.
So until we fix it, I don't think CC_STACKPROTECTOR is usable on PPC 
with modern versions of GCC.

Christophe

>
> Thanks,
> Christian.
>
>>
>> diff --git a/arch/powerpc/platforms/powermac/Makefile b/arch/powerpc/platforms/powermac/Makefile
>> index 1eb7b45..c7dcab9 100644
>> --- a/arch/powerpc/platforms/powermac/Makefile
>> +++ b/arch/powerpc/platforms/powermac/Makefile
>> @@ -1,4 +1,4 @@
>> -CFLAGS_bootx_init.o  		+= -fPIC
>> +CFLAGS_bootx_init.o  		+= -fPIC -fno-stack-protector
>>
>>  ifdef CONFIG_FUNCTION_TRACER
>>  # Do not trace early boot code
>>
>>
>> Thanks,
>> Christian.
>> --
>> BOFH excuse #156:
>>
>> Zombie processes haunting the computer
>>
>