From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42KwH50mBGzF3F5 for ; Wed, 26 Sep 2018 21:11:12 +1000 (AEST) Received: by mail-wm1-x343.google.com with SMTP id b19-v6so1829120wme.3 for ; Wed, 26 Sep 2018 04:11:12 -0700 (PDT) Subject: Re: Re: [PATCH] kdb: use correct pointer when 'btc' calls 'btt' To: Christophe Leroy Cc: Jason Wessel , Michael Ellerman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kgdb-bugreport@lists.sourceforge.net, stable@vger.kernel.org, me@tobin.cc References: <20180916190610.vzqxwps7zqy2zc6o@holly.lan> From: Daniel Thompson Message-ID: <5f0e0241-b7ab-b5fa-de0e-01abdbc85770@linaro.org> Date: Wed, 26 Sep 2018 12:11:06 +0100 MIME-Version: 1.0 In-Reply-To: <20180916190610.vzqxwps7zqy2zc6o@holly.lan> Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 >> Cc: # 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 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; >> } >> 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 >>