powerpc: Don't write to DABR on >= Power8 if DAWR is disabled

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flush_thread() calls __set_breakpoint() via set_debug_reg_defaults()
without checking ppc_breakpoint_available(). On Power8 or later CPUs
which have the DAWR feature disabled that will cause a write to the
DABR which is incorrect as those CPUs don't have a DABR.

Fix it two ways, by checking ppc_breakpoint_available() in
set_debug_reg_defaults(), and also by reworking __set_breakpoint() to
only write to DABR on Power7 or earlier.

Fixes: 9654153158 ("powerpc: Disable DAWR in the base POWER9 CPU features")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Rework the logic in __set_breakpoint()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Nicholas Piggin 2018-04-01 15:50:36 +10:00 • committed by Michael Ellerman

parent e303c08787

commit 252988cbf0

1 changed files with 8 additions and 2 deletions

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arch/powerpc/kernel/process.c

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