From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Santosh Sivaraj <santosh@fossix.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Mahesh Salgaonkar <mahesh@linux.ibm.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>,
Reza Arbab <arbab@linux.ibm.com>
Subject: Re: [v2 12/12] powerpc/64s: Save r13 in machine_check_common_early
Date: Tue, 02 Jul 2019 16:19:04 +1000 [thread overview]
Message-ID: <1562048251.j2f6zct1ph.astroid@bobo.none> (raw)
In-Reply-To: <20190702051932.511-13-santosh@fossix.org>
Santosh Sivaraj's on July 2, 2019 3:19 pm:
> 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]
>
> To fix, ensure that r13 is properly restored after an MCE.
>
> This commit is needed for testing this series, this is a possible simulator
> bug.
This introduces a bug, of course -- MCE occurring when r13 != PACA
will corrupt r13.
> ---
> 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 311f1392a2ec..932d8d05892c 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -265,6 +265,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
> EXC_REAL_END(machine_check, 0x200, 0x100)
> EXC_VIRT_NONE(0x4200, 0x100)
> TRAMP_REAL_BEGIN(machine_check_common_early)
> + SET_SCRATCH0(r13) /* save r13 */
> EXCEPTION_PROLOG_1(PACA_EXMC, NOTEST, 0x200)
> /*
> * Register contents:
> --
> 2.20.1
>
>
prev parent reply other threads:[~2019-07-02 6:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 5:19 [v2 00/12] powerpc: implement machine check safe memcpy Santosh Sivaraj
2019-07-02 5:19 ` [v2 01/12] powerpc/mce: Make machine_check_ue_event() static Santosh Sivaraj
2019-07-02 5:19 ` [v2 02/12] powerpc/mce: Bug fixes for MCE handling in kernel space Santosh Sivaraj
2019-07-02 5:19 ` [v2 03/12] powerpc/mce: Add MCE notification chain Santosh Sivaraj
2019-07-02 14:55 ` Reza Arbab
2019-07-02 5:19 ` [v2 04/12] powerpc/mce: Move machine_check_ue_event() call Santosh Sivaraj
2019-07-02 5:19 ` [v2 05/12] powerpc/mce: Allow notifier callback to handle MCE Santosh Sivaraj
2019-07-02 5:19 ` [v2 06/12] powerpc/mce: Add fixup address to UE events Santosh Sivaraj
2019-07-02 5:19 ` [v2 07/12] powerpc/memcpy: Add memcpy_mcsafe for pmem Santosh Sivaraj
2019-07-02 5:19 ` [v2 08/12] powerpc/mce: Handle memcpy_mcsafe() Santosh Sivaraj
2019-07-02 5:19 ` [v2 09/12] powerpc/mce: Enable MCE notifiers in external modules Santosh Sivaraj
2019-07-02 6:17 ` Nicholas Piggin
2019-07-02 9:33 ` Mahesh Jagannath Salgaonkar
2019-07-03 17:20 ` Reza Arbab
2019-07-04 2:36 ` Nicholas Piggin
2019-07-05 2:50 ` Reza Arbab
2019-07-05 5:29 ` Nicholas Piggin
2019-07-08 15:23 ` Reza Arbab
2019-07-02 5:19 ` [v2 10/12] powerpc/memcpy_mcsafe: return remaining bytes Santosh Sivaraj
2019-07-02 5:19 ` [v2 11/12] powerpc: add machine check safe copy_to_user Santosh Sivaraj
2019-07-02 5:19 ` [v2 12/12] powerpc/64s: Save r13 in machine_check_common_early Santosh Sivaraj
2019-07-02 6:19 ` Nicholas Piggin [this message]
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