Re: [PATCH] kdb: use correct pointer when 'btc' calls 'btt'

[Christophe LEROY]

Le 26/09/2018 Ã 13:11, Daniel Thompson a ÃcritÂ:
> 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@xxxxxx>
> > > Cc: <stable@xxxxxxxxxxxxxxx> # 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@xxxxxxxxxx>


Ok, thanks for the review, but do I have to do anything really ?

The Fixes: and now your Reviewed-by: appear automatically in patchwork 
(https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=65715), 
so I believe they'll be automatically included when Jason or someone 
else takes the patch, no ?

Christophe

> 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.
> >
> > > ---
> > > Â kernel/debug/kdb/kdb_bt.c | 4 ++--
> > > Â 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)
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ kdb_printf("no process for cpu %ld\n", cpu);
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return 0;
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ }
> > > -ÂÂÂÂÂÂÂÂÂÂÂ sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
> > > +ÂÂÂÂÂÂÂÂÂÂÂ sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ kdb_parse(buf);
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ return 0;
> > > ÂÂÂÂÂÂÂÂÂ }
> > > ÂÂÂÂÂÂÂÂÂ kdb_printf("btc: cpu status: ");
> > > ÂÂÂÂÂÂÂÂÂ kdb_parse("cpu\n");
> > > ÂÂÂÂÂÂÂÂÂ for_each_online_cpu(cpu) {
> > > -ÂÂÂÂÂÂÂÂÂÂÂ sprintf(buf, "btt 0x%p\n", KDB_TSK(cpu));
> > > +ÂÂÂÂÂÂÂÂÂÂÂ sprintf(buf, "btt 0x%px\n", KDB_TSK(cpu));
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ kdb_parse(buf);
> > > ÂÂÂÂÂÂÂÂÂÂÂÂÂ touch_nmi_watchdog();
> > > ÂÂÂÂÂÂÂÂÂ }
> > > --
> > > 2.13.3