powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct

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We need r1 to be properly set before activating MMU, so
reading task_struct->stack must be done with MMU off.

This means we need an additional register to play with MSR
bits while r11 now points to the stack. For that, move r10
back to CR (As is already done for hash MMU) and use r10.

We still don't have r1 correct yet when we activate MMU.
It is done in following patch.

Fixes: 028474876f ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a027d447022a006c9c4958ac734128e577a3c5c1.1599486108.git.christophe.leroy@csgroup.eu

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Christophe Leroy 2020-09-07 13:42:09 +00:00 • committed by Michael Ellerman

parent 7fdf966bed

commit c118c7303a

2 changed files with 6 additions and 31 deletions

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6

arch/powerpc/kernel/head_32.S

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31

arch/powerpc/kernel/head_32.h

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