Messages in this thread | | | Date | Wed, 2 Dec 2020 11:39:43 +0100 | From | Thomas Bogendoerfer <> | Subject | Re: [PATCH] MIPS: KASLR: Fix sync_icache() trapped in loop when synci_step is zero |
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On Wed, Dec 02, 2020 at 11:00:05AM +0800, Jinyang He wrote: > Reading synci_step by using rdhwr instruction may return zero if no cache > need be synchronized. On the one hand, to make sure all load operation and > store operation finished we do __sync() for every platform. On the other > hand, some platform need operate synci one time although step is zero.
Should this be someting like: Avoid endless loop, if no synci is needed ?
> diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c > index 57bdd276..47aeb33 100644 > --- a/arch/mips/kernel/relocate.c > +++ b/arch/mips/kernel/relocate.c > @@ -64,7 +64,7 @@ static void __init sync_icache(void *kbase, unsigned long kernel_length) > : "r" (kbase)); > > kbase += step; > - } while (kbase < kend); > + } while (step && kbase < kend);
why not do a
if (step == 0) return;
before entering the loop ? According to MIPS32PRA no synci is needed, if stepi value is zero.
Thomas.
PS: Does anybody know a reason, why this code doesn't use an old fashioned dache/icache flushing, which might be slower but would work also on legecy cores ?
-- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
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