[PATCH] powerpc: Inline setup_kup()

[Christophe Leroy]

Le 15/12/2020 à 02:42, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy at csgroup.eu> writes:
>> Le 14/12/2020 à 13:30, Michael Ellerman a écrit :
>>> setup_kup() is used by both 64-bit and 32-bit code. However on 64-bit
>>> it must not be __init, because it's used for CPU hotplug, whereas on
>>> 32-bit it should be __init because it calls setup_kuap/kuep() which
>>> are __init.
>>>
>>> We worked around that problem in the past by marking it __ref, see
>>> commit 67d53f30e23e ("powerpc/mm: fix section mismatch for
>>> setup_kup()").
>>>
>>> Marking it __ref basically just omits it from section mismatch
>>> checking, which can lead to bugs, and in fact it did, see commit
>>> 44b4c4450f8d ("powerpc/64s: Mark the kuap/kuep functions non __init")
>>>
>>> We can avoid all these problems by just making it static inline.
>>> Because all it does is call other functions, making it inline actually
>>> shrinks the 32-bit vmlinux by ~76 bytes.
>>>
>>> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
>>> ---
>>>    arch/powerpc/include/asm/kup.h | 8 ++++++--
>>>    arch/powerpc/mm/init-common.c  | 6 ------
>>>    2 files changed, 6 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
>>> index 5a9820c54da9..46b12c6dc728 100644
>>> --- a/arch/powerpc/include/asm/kup.h
>>> +++ b/arch/powerpc/include/asm/kup.h
>>> @@ -49,8 +49,6 @@ extern bool disable_kuap;
>>>    
>>>    #include <linux/pgtable.h>
>>>    
>>> -void setup_kup(void);
>>> -
>>>    #ifdef CONFIG_PPC_KUEP
>>>    void setup_kuep(bool disabled);
>>>    #else
>>> @@ -85,6 +83,12 @@ static inline void restore_user_access(unsigned long flags) { }
>>>    #endif /* CONFIG_PPC_BOOK3S_64 */
>>>    #endif /* CONFIG_PPC_KUAP */
>>>    
>>> +static inline void setup_kup(void)
>>
>> Should it be __always_inline ?
> 
> Yes I guess so, will fix. Thanks for reviewing.
> 

While we are talking about __always_inline, do you plan to take the following patch this cycle ?

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/a1d31f84ddb0926813b17fcd5cc7f3fa7b4deac2.1602759123.git.christophe.leroy@csgroup.eu/

Christophe