linux-kernel - [PATCH] kdb: use correct pointer when 'btc' calls 'btt'

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Message-Id: <ff05bd36b338f4f914780176e9eba8138e1b254b.1536927765.git.christophe.leroy@c-s.fr>
Date:   Fri, 14 Sep 2018 12:35:44 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Jason Wessel <jason.wessel@...driver.com>,
        Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        kgdb-bugreport@...ts.sourceforge.net, stable@...r.kernel.org
Subject: [PATCH] kdb: use correct pointer when 'btc' calls 'btt'

On a powerpc 8xx, 'btc' fails as follows:

Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry
kdb> btc
btc: cpu status: Currently on cpu 0
Available cpus: 0
kdb_getarea: Bad address 0x0

when booting the kernel with 'debug_boot_weak_hash', it fails as well

Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry
kdb> btc
btc: cpu status: Currently on cpu 0
Available cpus: 0
kdb_getarea: Bad address 0xba99ad80

On other platforms, Oopses have been observed too, see
https://github.com/linuxppc/linux/issues/139

This is due to btc calling 'btt' with %p pointer as an argument.

This patch replaces %p by %px to get the real pointer value as
expected by 'btt'

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Cc: <stable@...r.kernel.org> # 4.15+
---
 kernel/debug/kdb/kdb_bt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 6ad4a9fcbd6f..7921ae4fca8d 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -179,14 +179,14 @@ kdb_bt(int argc, const char **argv)
 				kdb_printf("no process for cpu %ld\n", cpu);
 				return 0;
 			}
-			sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
+			sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
 			kdb_parse(buf);
 			return 0;
 		}
 		kdb_printf("btc: cpu status: ");
 		kdb_parse("cpu\n");
 		for_each_online_cpu(cpu) {
-			sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
+			sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
 			kdb_parse(buf);
 			touch_nmi_watchdog();
 		}
-- 
2.13.3