Re: [PATCH v2 36/43] powerpc/32: Set current->thread.regs in C interrupt entry

Excerpts from Christophe Leroy's message of March 11, 2021 10:38 pm:

Le 11/03/2021 à 11:38, Christophe Leroy a écrit :

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Le 10/03/2021 à 02:33, Nicholas Piggin a écrit :

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Excerpts from Christophe Leroy's message of March 9, 2021 10:10 pm:

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No need to do that is assembly, do it in C.

Hmm. No issues with the patch as such, but why does ppc32 need this but
not 64? AFAIKS 64 sets this when a thread is created.

Looks like ppc64 was doing the same in function save_remaining_regs() in arch/ppc64/kernel/head.S 
until commit https://github.com/mpe/linux-fullhistory/commit/e5bb080d

But I can't find what happend to it in that commit.

Where is it done now ? Maybe that's also already done for ppc32.

I digged a bit more and found a later bug fix which adds that setting of current->thread.regs at 
task creation: https://github.com/mpe/linux-fullhistory/commit/3eac1897

That was in the ppc64 tree only at that time, and was merged into the common powerpc tree via commit 
https://github.com/mpe/linux-fullhistory/commit/06d67d54

Nice archaeology!

So we have it for both ppc32 and ppc64 and ppc32 doesn't need to do it at exception entry anymore. 
I'll remove it.

Good, that's what I hoped (otherwise ppc64 would have been missing 
something).

Thanks,
Nick