From: Santosh Sivaraj <santosh@fossix.org>
To: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Mahesh Salgaonkar <mahesh@linux.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>,
Reza Arbab <arbab@linux.ibm.com>
Subject: [v4 6/6] powerpc/64s: save r13 in MCE handler (simulator workaroud)
Date: Sat, 6 Jul 2019 15:16:47 +0530 [thread overview]
Message-ID: <20190706094647.15427-7-santosh@fossix.org> (raw)
In-Reply-To: <20190706094647.15427-1-santosh@fossix.org>
From: Reza Arbab <arbab@linux.ibm.com>
Testing my memcpy_mcsafe() work in progress with an injected UE, I get
an error like this immediately after the function returns:
BUG: Unable to handle kernel data access at 0x7fff84dec8f8
Faulting instruction address: 0xc0080000009c00b0
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in: mce(O+) vmx_crypto crc32c_vpmsum
CPU: 0 PID: 1375 Comm: modprobe Tainted: G O 5.1.0-rc6 #267
NIP: c0080000009c00b0 LR: c0080000009c00a8 CTR: c000000000095f90
REGS: c0000000ee197790 TRAP: 0300 Tainted: G O (5.1.0-rc6)
MSR: 900000000280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 88002826 XER: 00040000
CFAR: c000000000095f8c DAR: 00007fff84dec8f8 DSISR: 40000000 IRQMASK: 0
GPR00: 000000006c6c6568 c0000000ee197a20 c0080000009c8400 fffffffffffffff2
GPR04: c0080000009c02e0 0000000000000006 0000000000000000 c000000003c834c8
GPR08: 0080000000000000 776a6681b7fb5100 0000000000000000 c0080000009c01c8
GPR12: c000000000095f90 00007fff84debc00 000000004d071440 0000000000000000
GPR16: 0000000100000601 c0080000009e0000 c000000000c98dd8 c000000000c98d98
GPR20: c000000003bba970 c0080000009c04d0 c0080000009c0618 c0000000001e5820
GPR24: 0000000000000000 0000000000000100 0000000000000001 c000000003bba958
GPR28: c0080000009c02e8 c0080000009c0318 c0080000009c02e0 0000000000000000
NIP [c0080000009c00b0] cause_ue+0xa8/0xe8 [mce]
LR [c0080000009c00a8] cause_ue+0xa0/0xe8 [mce]
After debugging we see that the first instruction at vector 200 is skipped by
the simulator, due to which r13 is not saved. Adding a nop at 0x200 fixes the
issue.
(This commit is needed for testing this series. This should not be taken
into the tree)
---
arch/powerpc/kernel/exceptions-64s.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 73ba246ca11d..8e43abb2a744 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -255,6 +255,7 @@ EXC_REAL_BEGIN(machine_check, 0x200, 0x100)
* some code path might still want to branch into the original
* vector
*/
+ nop
SET_SCRATCH0(r13) /* save r13 */
EXCEPTION_PROLOG_0(PACA_EXMC)
BEGIN_FTR_SECTION
--
2.20.1
prev parent reply other threads:[~2019-07-06 9:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-06 9:46 [v4 0/6] powerpc: implement machine check safe memcpy Santosh Sivaraj
2019-07-06 9:46 ` [v4 1/6] powerpc/mce: Make machine_check_ue_event() static Santosh Sivaraj
2019-07-06 9:46 ` [v4 2/6] powerpc/mce: Bug fixes for MCE handling in kernel space Santosh Sivaraj
2019-07-06 9:46 ` [v4 3/6] powerpc/memcpy: Add memcpy_mcsafe for pmem Santosh Sivaraj
2019-07-06 9:46 ` [v4 4/6] powerpc/mce: Handle UE event for memcpy_mcsafe Santosh Sivaraj
2019-07-06 9:46 ` [v4 5/6] powerpc: add machine check safe copy_to_user Santosh Sivaraj
2019-07-06 10:17 ` Christophe Leroy
2019-07-06 9:46 ` Santosh Sivaraj [this message]
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