powerpc: Rework set_dabr so it can take a DABRX value as well

Rework set_dabr to take a DABRX value as well.

Both the pseries and PS3 hypervisors do some checks on the DABRX
values that are passed in the hcall.  This patch stops bogus values
from being passed to hypervisor.  Also, in the case where we are
clearing the breakpoint, where DABR and DABRX are zero, we modify the
DABRX value to make it valid so that the hcall won't fail.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index c10fc28b909..79d8e56470d 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -960,6 +960,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
                 thread->ptrace_bps[0] = bp;
                 ptrace_put_breakpoints(task);
                 thread->dabr = data;
+                thread->dabrx = DABRX_ALL;
                 return 0;
         }
 
@@ -983,6 +984,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 
         /* Move contents to the DABR register */
         task->thread.dabr = data;
+        task->thread.dabrx = DABRX_ALL;
 #else /* CONFIG_PPC_ADV_DEBUG_REGS */
         /* As described above, it was assumed 3 bits were passed with the data
          *  address, but we will assume only the mode bits will be passed
@@ -1397,6 +1399,7 @@ static long ppc_set_hwdebug(struct task_struct *child,
                 dabr |= DABR_DATA_WRITE;
 
         child->thread.dabr = dabr;
+        child->thread.dabrx = DABRX_ALL;
 
         return 1;
 #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */