From: "Aneesh Kumar K.V" <aneesh.kumar@linux•vnet.ibm.com>
To: Anshuman Khandual <khandual@linux•vnet.ibm.com>,
Mahesh J Salgaonkar <mahesh@linux•vnet.ibm.com>
Cc: linuxppc-dev <linuxppc-dev@ozlabs•org>,
Paul Mackerras <paulus@samba•org>,
Anton Blanchard <anton@samba•org>
Subject: Re: [PATCH] powerpc: Fix the corrupt r3 error during MCE handling.
Date: Mon, 15 Jul 2013 11:36:16 +0530 [thread overview]
Message-ID: <87k3ksjr1j.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <51DE4887.6050206@linux.vnet.ibm.com>
Anshuman Khandual <khandual@linux•vnet.ibm.com> writes:
> On 07/10/2013 06:32 PM, Mahesh J Salgaonkar wrote:
>> From: Mahesh Salgaonkar <mahesh@linux•vnet.ibm.com>
>>
>> During Machine Check interrupt on pseries platform, R3 generally points to
>> memory region inside RTAS (FWNMI) area. We see r3 corruption because when RTAS
>> delivers the machine check exception it passes the address inside FWNMI area
>> with the top most bit set. This patch fixes this issue by masking top two bit
>> in machine check exception handler.
>>
>> Signed-off-by: Mahesh Salgaonkar <mahesh@linux•vnet.ibm.com>
>> ---
>> arch/powerpc/platforms/pseries/ras.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
>> index 7b3cbde..721c058 100644
>> --- a/arch/powerpc/platforms/pseries/ras.c
>> +++ b/arch/powerpc/platforms/pseries/ras.c
>> @@ -287,6 +287,9 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
>> unsigned long *savep;
>> struct rtas_error_log *h, *errhdr = NULL;
>>
>> + /* Mask top two bits */
>> + regs->gpr[3] &= ~(0x3UL << 62);
>
> We need to replace this "62" with a shift macro specifying the significance
> of these top two address bits in the real mode.
huh??
(gdb) p/t 0x3ull << 62
$4 = 1100000000000000000000000000000000000000000000000000000000000000
Why you need an extra comment to explain 62. But yes, we can possibly
write that this is an RTAS bug
-aneesh
next prev parent reply other threads:[~2013-07-15 6:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-10 13:02 [PATCH] powerpc: Fix the corrupt r3 error during MCE handling Mahesh J Salgaonkar
2013-07-10 14:11 ` Aneesh Kumar K.V
2013-07-11 4:34 ` Mahesh Jagannath Salgaonkar
2013-07-11 4:42 ` Benjamin Herrenschmidt
2013-07-11 5:54 ` Anshuman Khandual
2013-07-15 6:06 ` Aneesh Kumar K.V [this message]
2013-07-15 6:18 ` Anshuman Khandual
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