Le 15/03/2022 à 22:11, Josh Poimboeuf a écrit :
> On Mon, Mar 14, 2022 at 08:21:30AM +0100, Christophe Leroy wrote:
>> System.map shows that vmlinux contains several instances of
>> __static_call_return0():
>>
>> c0004fc0 t __static_call_return0
>> c0011518 t __static_call_return0
>> c00d8160 t __static_call_return0
>>
>> arch_static_call_transform() uses the middle one to check whether we are
>> setting a call to __static_call_return0 or not:
>>
>> c0011520 <arch_static_call_transform>:
>> c0011520: 3d 20 c0 01 lis r9,-16383 <== r9 =
>> 0xc001 << 16
>> c0011524: 39 29 15 18 addi r9,r9,5400 <== r9 += 0x1518
>> c0011528: 7c 05 48 00 cmpw r5,r9 <== r9 has
>> value 0xc0011518 here
>>
>> So if static_call_update() is called with one of the other instances of
>> __static_call_return0(), arch_static_call_transform() won't recognise it.
>>
>> In order to work properly, global single instance of __static_call_return0()
>> is required.
>>
>> Fixes: 3f2a8fc4b15d ("static_call/x86: Add __static_call_return0()")
>> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
>
> Acked-by: Josh Poimboeuf <jpoim...@redhat.com>
>
Thanks for this Ack.
By the way I sent version v2 before your Ack for a missing #include
Christophe
