[PATCH 2/2] powerpc: Fix DABR write in the case of DAWR disabled

[Nicholas Piggin]

flush_thread will call set_breakpoint via set_debug_reg_defaults,
and cause POWER8 and above CPUs without the DAWR feature to try
to write to DAWR.

Cc: Michael Neuling <mi...@neuling.org>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/kernel/process.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 24a591b4dbe9..bfcf5437083c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -718,7 +718,8 @@ static void set_debug_reg_defaults(struct thread_struct 
*thread)
 {
        thread->hw_brk.address = 0;
        thread->hw_brk.type = 0;
-       set_breakpoint(&thread->hw_brk);
+       if (ppc_breakpoint_available())
+               set_breakpoint(&thread->hw_brk);
 }
 #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
 #endif /* CONFIG_PPC_ADV_DEBUG_REGS */
@@ -814,10 +815,14 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
 {
        memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));
 
-       if (cpu_has_feature(CPU_FTR_DAWR))
-               set_dawr(brk);
-       else
+       if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
+               if (cpu_has_feature(CPU_FTR_DAWR))
+                       set_dawr(brk);
+               else
+                       WARN_ON_ONCE(1);
+       } else {
                set_dabr(brk);
+       }
 }
 
 void set_breakpoint(struct arch_hw_breakpoint *brk)
-- 
2.16.3