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powerpc/64: Interrupts save PPR on stack rather than thread_struct

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PPR is the odd register out when it comes to interrupt handling, it is
saved in current->thread.ppr while all others are saved on the stack.

The difficulty with this is that accessing thread.ppr can cause a SLB
fault, but the SLB fault handler implementation in C change had
assumed the normal exception entry handlers would not cause an SLB
fault.

Fix this by allocating room in the interrupt stack to save PPR.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2018-10-13 00:15:16 +11:00
committed by Michael Ellerman
parent 3eeacd9f4e
commit 4c2de74cc8
7 changed files with 19 additions and 23 deletions
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2
arch/powerpc/kernel/process.c
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@@ -1710,7 +1710,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
p->thread.dscr = mfspr(SPRN_DSCR);
}
if (cpu_has_feature(CPU_FTR_HAS_PPR))
p->thread.ppr = INIT_PPR;
childregs->ppr = DEFAULT_PPR;
p->thread.tidr = 0;
#endif