On 04/10/2014 03:54 PM, Benjamin Herrenschmidt wrote:
On Thu, 2014-04-10 at 02:51 -0400, Mike Qiu wrote:
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc000000000041d78
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c000000000041d78] .sys_pciconfig_iobase+0x68/0x1f0
LR [c000000000041e0c] .sys_pciconfig_iobase+0xfc/0x1f0
Call Trace:
[c0000003b4787db0] [c000000000041e0c] .sys_pciconfig_iobase+0xfc/0x1f0
(unreliable)
[c0000003b4787e30] [c000000000009ed8] syscall_exit+0x0/0x98
This bug was introduced by commit 3bc955987fb377f3c95bc29deb498e96819b8451
The root cause was the 'bus' has been set to null while try to access
bus->next.
Good catch. Out of curiosity, what is using that syscall nowadays ? It's
been long buggy in all sort of ways and is pretty much deprecated...
I just boot my Power7 machine with newest mainline kernel, it happens
and block the system.
I really do not know which software use this syscall, need to do some
research on it.
Thanks
Mike
Cheers,
Ben.
Signed-off-by: Mike Qiu <qiud...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/pci_64.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 2a47790..7b6c1ae 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -209,6 +209,7 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
{
struct pci_controller* hose;
struct pci_bus *bus = NULL;
+ struct pci_bus *tmp_bus = NULL;
struct device_node *hose_node;
/* Argh ! Please forgive me for that hack, but that's the
@@ -229,10 +230,12 @@ long sys_pciconfig_iobase(long which, unsigned long
in_bus,
* used on pre-domains setup. We return the first match
*/
- list_for_each_entry(bus, &pci_root_buses, node) {
- if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
+ list_for_each_entry(tmp_bus, &pci_root_buses, node) {
+ if (in_bus >= tmp_bus->number &&
+ in_bus <= tmp_bus->busn_res.end) {
+ bus = tmp_bus;
break;
- bus = NULL;
+ }
}
if (bus == NULL || bus->dev.of_node == NULL)
return -ENODEV;
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