Messages in this thread | | | From | Christophe Leroy <> | Subject | Re: [PATCH] static_call: Don't make __static_call_return0 static | Date | Wed, 16 Mar 2022 07:11:14 +0000 |
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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.leroy@csgroup.eu> > > Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> >
Thanks for this Ack.
By the way I sent version v2 before your Ack for a missing #include
Christophe
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