Re: [PATCH] scsi: fc: force inlining of wwn conversion functions

From: Quinn Tran
Date: Fri Apr 22 2016 - 19:17:20 EST

Next message: Jeff Kirsher: "Re: linux-next: build failure after merge of the net-next tree"
Previous message: Alexandre Belloni: "Re: [PATCH 1/2] ARM: PIE infrastructure"
In reply to: Josh Poimboeuf: "[PATCH] scsi: fc: force inlining of wwn conversion functions"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Current kernel (4.6.0-rc4+) + GCC 5.3.0 definitely truncated qla2x00_get_host_fabric_name() routine. Just like Josh indicated, weâre dropping down to the next routine.

root@mars:/sys/class/fc_host/host3 2016-04-22 16:07:30
> cat fabric_name
Killed
ââ
static void
qla2x00_get_host_fabric_name(struct Scsi_Host *shost)
{
32d0: e8 00 00 00 00 callq 32d5 <qla2x00_get_host_fabric_name+0x5>
32d5: 55 push %rbp
32d6: 48 89 e5 mov %rsp,%rbp
32d9: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)

00000000000032e0 <qla2x00_get_starget_node_name>:
qla2x00_get_starget_node_name():
/root/qt/linux.git/drivers/scsi/qla2xxx/qla_attr.c:1756
fc_host_port_type(shost) = port_type;
}

----

Apr 22 16:07:50 mars kernel: BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
Apr 22 16:07:50 mars kernel: IP: [<ffffffff813f72d7>] scsi_is_host_device+0x7/0x20
Apr 22 16:07:50 mars kernel: PGD 7fe1c8067 PUD 7f5c72067 PMD 0
Apr 22 16:07:50 mars kernel: Oops: 0000 [#1] SMP
Apr 22 16:07:50 mars kernel: Modules linked in: qla2xxx scsi_transport_fc ebtable_nat ebtables ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4
...
dm_mirror(E) dm_region_hash(E) dm_log(E) dm_mod(E) [last unloaded: qla2xxx]
Apr 22 16:07:50 mars kernel: CPU: 8 PID: 10452 Comm: cat Tainted: G E 4.6.0-rc4+ #2
Apr 22 16:07:50 mars kernel: Hardware name: HP ProLiant DL380 G7, BIOS P67 05/05/2011
Apr 22 16:07:50 mars kernel: task: ffff8807fcd1a880 ti: ffff8807ff128000 task.ti: ffff8807ff128000
Apr 22 16:07:50 mars kernel: RIP: 0010:[<ffffffff813f72d7>] [<ffffffff813f72d7>] scsi_is_host_device+0x7/0x20
Apr 22 16:07:50 mars kernel: RSP: 0018:ffff8807ff12bcf0 EFLAGS: 00010246
Apr 22 16:07:50 mars kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff880ffe8ade88
Apr 22 16:07:50 mars kernel: RDX: ffff8807f5db9000 RSI: ffff880ffed43340 RDI: 0000000000000000
Apr 22 16:07:50 mars kernel: RBP: ffff8807ff12bd08 R08: ffff88101f45ac38 R09: ffff8807fccef280
Apr 22 16:07:50 mars kernel: R10: 0000000000000000 R11: 0000000000000000 R12: ffff88101b7e6000
Apr 22 16:07:50 mars kernel: R13: ffff8807fdaf1f00 R14: ffff8800dad379c0 R15: 0000000000000001
Apr 22 16:07:50 mars kernel: FS: 00007fd569512700(0000) GS:ffff88081fc80000(0000) knlGS:0000000000000000
Apr 22 16:07:50 mars kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Apr 22 16:07:50 mars kernel: CR2: 0000000000000058 CR3: 00000007f23f4000 CR4: 00000000000006e0
Apr 22 16:07:50 mars kernel: Stack:
Apr 22 16:07:50 mars kernel: ffffffffa0759db5 ffff88101b7e6000 ffff8807f5db9000 ffff8807ff12bd10
Apr 22 16:07:50 mars kernel: ffff8807ff12bd30 ffffffffa065b1bb ffff880ffed43340 ffffffff8166d950
Apr 22 16:07:50 mars kernel: ffff8807ff12bd50 ffffffff813c9e30 ffffffff815ccfb2 ffff8800dad379c0
Apr 22 16:07:50 mars kernel: Call Trace:
Apr 22 16:07:50 mars kernel: [<ffffffffa0759db5>] ? qla2x00_get_starget_node_name+0x25/0x90 [qla2xxx]
Apr 22 16:07:50 mars kernel: [<ffffffffa065b1bb>] ? show_fc_host_fabric_name+0x4b/0x80 [scsi_transport_fc]
Apr 22 16:07:50 mars kernel: [<ffffffff813c9e30>] ? dev_attr_show+0x20/0x50

Regards,
Quinn Tran

-----Original Message-----
From: <linux-scsi-owner@xxxxxxxxxxxxxxx> on behalf of Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Date: Tuesday, April 19, 2016 at 6:56 AM
To: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>, "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: linux-scsi <linux-scsi@xxxxxxxxxxxxxxx>, linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>, Denys Vlasenko <dvlasenk@xxxxxxxxxx>, Thomas Graf <tgraf@xxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, David Rientjes <rientjes@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, "jamborm@xxxxxxxxxxx" <jamborm@xxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>, Dept-Eng QLA2xxx Upstream <qla2xxx-upstream@xxxxxxxxxx>
Subject: [PATCH] scsi: fc: force inlining of wwn conversion functions

>objtool reports [1] the following warning:
>
> drivers/scsi/qla2xxx/qla_attr.o: warning: objtool: qla2x00_get_host_fabric_name() falls through to next function qla2x00_get_starget_port_name()
>
>This warning is due to a gcc bug [2] which causes corrupt code:
>
> 0000000000002f53 <qla2x00_get_host_fabric_name>:
> 2f53: 55 push %rbp
> 2f54: 48 89 e5 mov %rsp,%rbp
>
> 0000000000002f57 <qla2x00_get_fc_host_stats>:
> 2f57: 55 push %rbp
> 2f58: b9 e8 00 00 00 mov $0xe8,%ecx
> 2f5d: 48 89 e5 mov %rsp,%rbp
> ...
>
>Note that qla2x00_get_host_fabric_name() is inexplicably truncated after
>setting up the frame pointer. It falls through to the next function,
>which is very bad.
>
>It occurs with the combination of the following two recent commits:
>
> bc27fb68aaad ("include/uapi/linux/byteorder, swab: force inlining of some byteswap operations")
> ef3fb2422ffe ("scsi: fc: use get/put_unaligned64 for wwn access")
>
>The call chain which appears to trigger the problem is:
>
> qla2x00_get_host_fabric_name()
> wwn_to_u64()
> get_unaligned_be64()
> be64_to_cpup()
> __be64_to_cpup()
>
>The bug requires very specific conditions to trigger. According to Martin
>Jambor (from the gcc bugzilla):
>
> "This bug can occur when an inlineable function containing a call to
> __builtin_constant_p, which checks a parameter or a value it
> references and a (possibly indirect) caller of the function actually
> passes a constant, but stores it using a type of a different size."
>
>There's no reliable way to avoid (or even detect) the bug. Until it
>gets fixed in released versions of gcc, the least intrusive workaround
>for this particular issue is to force the wwn conversion functions to be
>inlined.
>
>[1] https://lists.01.org/pipermail/kbuild-all/2016-April/019579.html
>[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646
>
>Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
>Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
>---
> include/scsi/scsi_transport_fc.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
>index bf66ea6..1919cd4 100644
>--- a/include/scsi/scsi_transport_fc.h
>+++ b/include/scsi/scsi_transport_fc.h
>@@ -796,12 +796,12 @@ fc_remote_port_chkready(struct fc_rport *rport)
> return result;
> }
>
>-static inline u64 wwn_to_u64(u8 *wwn)
>+static __always_inline u64 wwn_to_u64(u8 *wwn)
> {
> return get_unaligned_be64(wwn);
> }
>
>-static inline void u64_to_wwn(u64 inm, u8 *wwn)
>+static __always_inline void u64_to_wwn(u64 inm, u8 *wwn)
> {
> put_unaligned_be64(inm, wwn);
> }
>--
>2.4.11
>
>--
>To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
>the body of a message to majordomo@xxxxxxxxxxxxxxx
>More majordomo info at http://vger.kernel.org/majordomo-info.html

Next message: Jeff Kirsher: "Re: linux-next: build failure after merge of the net-next tree"
Previous message: Alexandre Belloni: "Re: [PATCH 1/2] ARM: PIE infrastructure"
In reply to: Josh Poimboeuf: "[PATCH] scsi: fc: force inlining of wwn conversion functions"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]