On 16/09/2018 20:06, Daniel Thompson wrote:
On Fri, Sep 14, 2018 at 12:35:44PM +0000, Christophe Leroy wrote:
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@c-s.fr Cc: stable@vger.kernel.org # 4.15+
Would a Fixes: be better here? Fixes: ad67b74d2469d9b82 ("printk: hash addresses printed with %p")
Christophe, When you add the Fixes: could you also add my
Reviewed-by: Daniel Thompson daniel.thompson@linaro.org
Thanks.
No blame attached to Tobin, but the fixes makes it super clear what changed and why this breaks kdb (which was not explicitly called out the patch description).
Daniel.
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;
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