Re: [PATCH] idle/x86: remove the call to boot_init_stack_canary() from cpu_startup_entry()

[Christophe LEROY <christophe.leroy@c-s.fr>]

Le 19/10/2018 à 12:01, Juergen Gross a écrit :
> On 19/10/2018 11:29, Christophe Leroy wrote:
>> commit d7880812b359 ("idle: Add the stack canary init to
>> cpu_startup_entry()") added the call to boot_init_stack_canary()
>> in cpu_startup_entry() in an #ifdef CONFIG_X86 statement, with
>> the intention to remove that #ifdef later.
>>
>> While implementing stack protector for powerpc, it has been
>> observed that calling boot_init_stack_canary() is also needed
>> for powerpc which uses per task (TLS) stack canary like the X86.
>>
>> However, calling boot_init_stack_canary() would break arches
>> using global stack canary (ARM, SH, MIPS and XTENSA).
>>
>> Instead of adding modifying the #ifdef in a
>> implemented the call to boot_init_stack_canary() in the function
>> calling cpu_startup_entry()
> 
> I can't parse this sentence.

Oops, git commit took the #if for a comment and droped it. Fixed in v2.

> 
>>
>> On x86, we have two functions calling cpu_startup_entry():
>> - start_secondary()
>> - cpu_bringup_and_idle()
>>
>> start_secondary() already calls boot_init_stack_canary().
>>
>> This patch adds the call to boot_init_stack_canary() in
>> cpu_bringup_and_idle() and removes it from cpu_startup_entry()
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> 
> With the commit message made understandable you can add my
> 
> Reviewed-by: Juergen Gross <jgross@suse.com>
> 

Thanks
Christophe