linux-kernel - [PATCH v2 15/16] powerpc/watchpoint/xmon: Don't allow breakpoint overwriting

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Message-Id: <20200401061309.92442-16-ravi.bangoria@linux.ibm.com>
Date:   Wed,  1 Apr 2020 11:43:08 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au, mikey@...ling.org
Cc:     apopple@...ux.ibm.com, paulus@...ba.org, npiggin@...il.com,
        christophe.leroy@....fr, naveen.n.rao@...ux.vnet.ibm.com,
        peterz@...radead.org, jolsa@...nel.org, oleg@...hat.com,
        fweisbec@...il.com, mingo@...nel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        ravi.bangoria@...ux.ibm.com
Subject: [PATCH v2 15/16] 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@...ux.ibm.com>
---
 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 508d353e7f06..a1e36501af25 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1382,6 +1382,10 @@ 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')
-- 
2.21.1