From 514db915e7b33e7eaf8e40192b93380f79b319b5 Mon Sep 17 00:00:00 2001
From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Date: Thu, 14 May 2020 16:47:40 +0530
Subject: [PATCH] powerpc/watchpoint/xmon: Don't allow breakpoint overwriting

References: jsc#SLE-12936
Patch-mainline: v5.8-rc1
Git-commit: 514db915e7b33e7eaf8e40192b93380f79b319b5

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
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/xmon/xmon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 30b3e3d99c0d..094bf4715f2c 100644
--- 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')
-- 
2.28.0