Messages in this thread | | | From | Michael Ellerman <> | Subject | Re: [PATCH] powerpc/32: indirect function call use bctrl rather than blrl in ret_from_kernel_thread | Date | Fri, 20 Aug 2021 22:15:11 +1000 |
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Christophe Leroy <christophe.leroy@csgroup.eu> writes: > Copied from commit 89bbe4c798bc ("powerpc/64: indirect function call > use bctrl rather than blrl in ret_from_kernel_thread") > > blrl is not recommended to use as an indirect function call, as it may > corrupt the link stack predictor.
Do we know if any 32-bit CPUs have a link stack predictor or similar?
cheers
> This is not a performance critical path but this should be fixed for > consistency. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > arch/powerpc/kernel/entry_32.S | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S > index 0273a1349006..61fdd53cdd9a 100644 > --- a/arch/powerpc/kernel/entry_32.S > +++ b/arch/powerpc/kernel/entry_32.S > @@ -161,10 +161,10 @@ ret_from_fork: > ret_from_kernel_thread: > REST_NVGPRS(r1) > bl schedule_tail > - mtlr r14 > + mtctr r14 > mr r3,r15 > PPC440EP_ERR42 > - blrl > + bctrl > li r3,0 > b ret_from_syscall > > -- > 2.25.0
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