From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
Steven Rostedt <srostedt@redhat.com>,
Scott Wood <scottwood@freescale.com>,
Eran Liberty <liberty@extricom.com>,
Alan Modra <amodra@au1.ibm.com>,
Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3)
Date: Wed, 20 Aug 2008 17:18:25 +1000 [thread overview]
Message-ID: <1219216705.21386.46.camel@pasglop> (raw)
In-Reply-To: <1219119431.8062.35.camel@pasglop>
Found the problem (or at least -a- problem), it's a gcc bug.
Well, first I must say the code generated by -pg is just plain
horrible :-)
Appart from that, look at the exit of, for example, __d_lookup, as
generated by gcc when ftrace is enabled:
c00c0498: 38 60 00 00 li r3,0
c00c049c: 81 61 00 00 lwz r11,0(r1)
c00c04a0: 80 0b 00 04 lwz r0,4(r11)
c00c04a4: 7d 61 5b 78 mr r1,r11
c00c04a8: bb 0b ff e0 lmw r24,-32(r11)
c00c04ac: 7c 08 03 a6 mtlr r0
c00c04b0: 4e 80 00 20 blr
As you can see, it restores r1 -before- it pops r24..r31 off
the stack ! I let you imagine what happens if an interrupt happens
just in between those two instructions (mr and lmw). We don't do
redzones on our ABI, so basically, the registers end up corrupted
by the interrupt.
Cheers,
Ben.
next prev parent reply other threads:[~2008-08-20 7:24 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-18 14:18 2.6.24-rc4: pci_remove_bus_device() => pci_scan_child_bus() => pci_bus_add_devices bug? Eran Liberty
2008-07-20 10:31 ` [PATCH 2.6.24-rc4] PCI: refuse to re-add a device to a bus upon pci_scan_child_bus() Eran Liberty
2008-07-20 16:48 ` Eran Liberty
2008-07-21 19:18 ` [PATCH 2.6.26] " Eran Liberty
2008-07-21 19:49 ` Matthew Wilcox
2008-07-22 8:21 ` eran liberty
2008-07-22 11:49 ` Matthew Wilcox
2008-07-22 13:08 ` Eran Liberty
2008-07-22 13:14 ` Eran Liberty
2008-07-22 14:13 ` Matthew Wilcox
2008-07-22 15:25 ` Eran Liberty
2008-07-22 16:52 ` Matthew Wilcox
2008-07-22 17:41 ` Eran Liberty
2008-07-22 18:11 ` Matthew Wilcox
2008-07-23 18:31 ` Eran Liberty
2008-07-27 11:01 ` Eran Liberty
2008-07-27 15:08 ` Matthew Wilcox
2008-08-18 8:08 ` ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) Eran Liberty
2008-08-18 15:07 ` Steven Rostedt
2008-08-18 15:47 ` Mathieu Desnoyers
2008-08-18 16:12 ` Steven Rostedt
2008-08-18 17:04 ` Mathieu Desnoyers
2008-08-18 17:21 ` Scott Wood
2008-08-18 18:27 ` Steven Rostedt
2008-08-18 18:29 ` Scott Wood
2008-08-19 1:53 ` Benjamin Herrenschmidt
2008-08-19 2:28 ` Steven Rostedt
2008-08-19 2:39 ` Benjamin Herrenschmidt
2008-08-19 2:41 ` Steven Rostedt
2008-08-19 2:47 ` Mathieu Desnoyers
2008-08-19 3:32 ` Steven Rostedt
2008-08-19 3:36 ` Mathieu Desnoyers
2008-08-19 4:00 ` Steven Rostedt
2008-08-19 16:47 ` Steven Rostedt
2008-08-19 17:34 ` Mathieu Desnoyers
2008-08-19 21:08 ` Steven Rostedt
2008-08-20 9:40 ` Nick Piggin
2008-08-19 21:47 ` Benjamin Herrenschmidt
2008-08-19 23:58 ` Jeremy Fitzhardinge
2008-08-20 1:17 ` Benjamin Herrenschmidt
2008-08-19 2:56 ` Benjamin Herrenschmidt
2008-08-19 3:12 ` Steven Rostedt
2008-08-19 4:17 ` Benjamin Herrenschmidt
2008-08-20 7:18 ` Benjamin Herrenschmidt [this message]
2008-08-20 13:14 ` Steven Rostedt
2008-08-20 13:19 ` Steven Rostedt
2008-08-20 13:36 ` Eran Liberty
2008-08-20 13:43 ` Steven Rostedt
2008-08-20 14:02 ` Eran Liberty
2008-08-20 14:55 ` Jon Smirl
2008-08-20 15:23 ` Steven Rostedt
2008-08-20 18:23 ` Eran Liberty
2008-08-20 18:33 ` Steven Rostedt
2008-08-20 15:27 ` Steven Rostedt
2008-08-20 21:37 ` Benjamin Herrenschmidt
2008-08-20 14:16 ` Josh Boyer
2008-08-20 14:22 ` Steven Rostedt
2008-08-20 14:50 ` Josh Boyer
2008-09-15 16:30 ` [PATCH 2.6.26] SERIAL DRIVER: Handle Multiple consecutive sysrq from the serial Eran Liberty
2008-09-17 23:46 ` Andrew Morton
2008-09-18 6:58 ` Eran Liberty
2008-08-20 21:36 ` ftrace introduces instability into kernel 2.6.27(-rc2,-rc3) Benjamin Herrenschmidt
2008-08-20 21:44 ` Steven Rostedt
2008-08-18 18:47 ` Steven Rostedt
2008-08-18 18:56 ` Scott Wood
2008-08-18 19:28 ` Steven Rostedt
2008-08-18 18:25 ` Eran Liberty
2008-08-18 18:41 ` Mathieu Desnoyers
2008-08-19 1:54 ` Benjamin Herrenschmidt
2008-08-19 9:56 ` Eran Liberty
2008-08-19 13:02 ` Mathieu Desnoyers
2008-08-19 21:46 ` Benjamin Herrenschmidt
2008-08-18 18:50 ` Steven Rostedt
2008-08-19 12:09 ` Eran Liberty
2008-08-19 13:05 ` Mathieu Desnoyers
2008-08-19 14:21 ` Eran Liberty
2008-08-19 14:42 ` Mathieu Desnoyers
2008-08-19 20:15 ` Steven Rostedt
2008-08-20 11:18 ` Eran Liberty
2008-08-20 13:12 ` Steven Rostedt
2008-08-19 1:51 ` Benjamin Herrenschmidt
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