powerpc/watchpoint/xmon: Don't allow breakpoint overwriting

Xmon allows overwriting breakpoints because it's supported by only
one DAWR. But with multiple DAWRs, overwriting becomes ambiguous
or unnecessary complicated. So let's not allow it.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-16-ravi.bangoria@linux.ibm.com

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 30b3e3d99c0d0cefeed6a82fb92592757112a175..094bf4715f2c2adfc496a145c2b9490f2636309f 100644 (file)
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1399,6 +1399,10 @@ bpt_cmds(void)
                        printf("Hardware data breakpoint not supported on this cpu\n");
                        break;
                }
+               if (dabr.enabled) {
+                       printf("Couldn't find free breakpoint register\n");
+                       break;
+               }
                mode = 7;
                cmd = inchar();
                if (cmd == 'r')