Hi Gabe,
It seems to me too that the problem is with the null request pointer.
Actually, The request pointer is generated in the cache_unit.cc file in the
inorder model files and the request pointer is passed on to the TLB
functions (translateAtomic and translateData) for translation.. But as I
wrote in my previous email too, the conditional assert statement that I am
putting there to check if memory was allocated or not for the request, is
not being satisfied, which is confusing me. There are no intermediate
function calls also. How else do I check if memory was allocated for this
request properly or not? Any suggestions how I can track it further?
/inorder/resources/cache_unit.cc :: setupMemRequest function {
if (inst->dataMemReq == NULL) {
inst->dataMemReq = new Request(cpu->asid[tid], aligned_addr,
acc_size, flags,
inst->instAddr(), cpu->readCpuId(),
tid);
* if(inst->dataMemReq == NULL)
assert(0);*
cache_req->memReq = inst->dataMemReq; <= This is the request
pointer, pointing to 0x0.
Thanks,
Reena
On Sun, May 15, 2011 at 4:19 PM, Gabe Black <[email protected]> wrote:
> Yeah, I'm pretty sure a request pointer being 0 is your problem. You can
> see in the stack trace that getVaddr is being called which gets some data
> out of the flags member. Since the request is at 0, the flags are at 0x18,
> and when that tries to check whether one of the flags is set by reading it's
> data, it does an illegal access. It looks like doTLBAccess is calling
> translateAtomic with a NULL request pointer which it got from somewhere.
>
Program received signal SIGSEGV, Segmentation fault.
0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18, flags=4
'\004')
at build/ALPHA_SE/base/flags.hh:
63
63 bool isSet(Type flags) const { return (_flags & flags); }
(gdb) bt
#0 0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18,
flags=4 '\004') at build/ALPHA_SE/base/flags.hh:63
#1 0x00000000004626d5 in Request::getVaddr (this=0x0)
at build/ALPHA_SE/mem/request.hh:368
#2 0x000000000090c067 in AlphaISA::TLB::translateData (this=0x1710400,
*req=0x0*, tc=0x1923a90, write=false) at
build/ALPHA_SE/arch/alpha/tlb.cc:452
#3 0x000000000090d1b5 in AlphaISA::TLB::translateAtomic (this=0x1710400,
*req=0x0*, tc=0x1923a90, mode=BaseTLB::Read)
at build/ALPHA_SE/arch/alpha/tlb.cc:587
*#4 0x000000000073a88c in CacheUnit::doTLBAccess (this=0x17268c0, inst=...,
cache_req=0x1bfe390, acc_size=8, flags=0, tlb_mode=BaseTLB::Read)
at build/ALPHA_SE/cpu/inorder/**resources/cache_unit.cc:431*
#5 0x000000000073d07b in CacheUnit::read (this=0x17268c0, inst=...,
addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
at build/ALPHA_SE/cpu/inorder/resources/cache_unit.cc:548
#6 0x00000000007d38f7 in InOrderCPU::read (this=0x172a160, inst=...,
addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
at build/ALPHA_SE/cpu/inorder/cpu.cc:1787
#7 0x00000000006d1b11 in InOrderDynInst::readBytes (this=0x26c3250,
addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
at build/ALPHA_SE/cpu/inorder/inorder_dyn_inst.cc:517
#8 0x00000000006d3795 in RefCountingPtr<FaultBase>
InOrderDynInst::read<unsigned long>(unsigned long, unsigned long&, unsigned
int) ()
>
> Gabe
>
>
> On 05/15/11 11:16, reena panda wrote:
>
> Hi Nilay,
> Thanks for your reply. I have made some changes to the code, but not to
> this part. I will remove my modifications and see if I am still running into
> the issue.
>
> The gdb trace also hints that req = 0x0 in translateData and
> translateAtomic functions. Can that be the problem? I am doubtful because if
> I put a check in setupMemRequest function in inorder/resources/cache_unit.cc
> file, it does not confirm the issue, i.e., if I include a check there, the
> assert condition does not hit before the program gets a seg fault. So, I am
> not sure if I am running into memory issues here.
>
> if (inst->dataMemReq == NULL) {
> inst->dataMemReq = new Request(cpu->asid[tid], aligned_addr,
> acc_size, flags,
> inst->instAddr(),
> cpu->readCpuId(),
> tid);
> * if(inst->dataMemReq == NULL)
> assert(0);*
>
> cache_req->memReq = inst->dataMemReq;
>
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18, flags=4
> '\004')
> at build/ALPHA_SE/base/flags.hh:
> 63
> 63 bool isSet(Type flags) const { return (_flags & flags); }
> (gdb) bt
> #0 0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18,
> flags=4 '\004') at build/ALPHA_SE/base/flags.hh:63
> #1 0x00000000004626d5 in Request::getVaddr (this=0x0)
> at build/ALPHA_SE/mem/request.hh:368
> #2 0x000000000090c067 in AlphaISA::TLB::translateData (this=0x1710400,
> *req=0x0*, tc=0x1923a90, write=false) at
> build/ALPHA_SE/arch/alpha/tlb.cc:452
> #3 0x000000000090d1b5 in AlphaISA::TLB::translateAtomic (this=0x1710400,
> *req=0x0*, tc=0x1923a90, mode=BaseTLB::Read)
> at build/ALPHA_SE/arch/alpha/tlb.cc:587
> #4 0x000000000073a88c in CacheUnit::doTLBAccess (this=0x17268c0, inst=...,
>
> cache_req=0x1bfe390, acc_size=8, flags=0, tlb_mode=BaseTLB::Read)
> at build/ALPHA_SE/cpu/inorder/resources/cache_unit.cc:431
> #5 0x000000000073d07b in CacheUnit::read (this=0x17268c0, inst=...,
> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
> at build/ALPHA_SE/cpu/inorder/resources/cache_unit.cc:548
> #6 0x00000000007d38f7 in InOrderCPU::read (this=0x172a160, inst=...,
> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
> at build/ALPHA_SE/cpu/inorder/cpu.cc:1787
> #7 0x00000000006d1b11 in InOrderDynInst::readBytes (this=0x26c3250,
> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
> at build/ALPHA_SE/cpu/inorder/inorder_dyn_inst.cc:517
> #8 0x00000000006d3795 in RefCountingPtr<FaultBase>
> InOrderDynInst::read<unsigned long>(unsigned long, unsigned long&, unsigned
> int) ()
>
> Thanks,
> Reena
>
> On Sun, May 15, 2011 at 12:08 AM, reena panda <[email protected]>wrote:
>
>> Just an addition. The benchmark runs fine till 50 million instructions,
>> this segmentation fault happens when I try to run the benchmark for more
>> number of instructions(by using maxinsts option). Can anybody give some
>> help?
>>
>> Thanks,
>> Reena
>>
>>
>> On Sat, May 14, 2011 at 11:41 PM, reena panda <[email protected]>wrote:
>>
>>> Hi,
>>> I am running m5 in ALPHA SE mode for inorder CPU model. I am getting a
>>> segmentation fault in the data translation section in tlb.cc file, when I am
>>> running for the SPEC2k6 mcf benchmark. I have not made any modifications to
>>> this part of the code. So, could anybody help me figure out the cause of the
>>> issue?
>>>
>>> Following is the gdb trace of the fault:- It shows that the fault is
>>> occuring when a translation is attempted in translatedata function in
>>> arch/tlb.cc file. The flag value returning from the isSet function is set at
>>> "4" => the Vaddr is valid (as per the mem/request.hh file). What might be
>>> causing this issue?
>>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>> 0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18, *flags=4
>>> '\004')*
>>> at build/ALPHA_SE/base/flags.hh:63
>>> 63 bool isSet(Type flags) const { return (_flags & flags); }
>>> (gdb) bt
>>> #0 0x0000000000431f87 in Flags<unsigned char>::isSet (this=0x18,
>>> flags=4 '\004') at build/ALPHA_SE/base/flags.hh:63
>>> #1 0x00000000004626d5 in Request::getVaddr (this=0x0)
>>> at build/ALPHA_SE/mem/request.hh:368
>>> #2 0x000000000090c067 in AlphaISA::TLB::translateData (this=0x1710400,
>>> req=0x0, tc=0x1923a90, write=false) at
>>> build/ALPHA_SE/arch/alpha/tlb.cc:452
>>> #3 0x000000000090d1b5 in AlphaISA::TLB::translateAtomic (this=0x1710400,
>>>
>>> req=0x0, tc=0x1923a90, mode=BaseTLB::Read)
>>> at build/ALPHA_SE/arch/alpha/tlb.cc:587
>>> #4 0x000000000073a88c in CacheUnit::doTLBAccess (this=0x17268c0,
>>> inst=...,
>>> cache_req=0x1bfe390, acc_size=8, flags=0, tlb_mode=BaseTLB::Read)
>>> at build/ALPHA_SE/cpu/inorder/resources/cache_unit.cc:431
>>> #5 0x000000000073d07b in CacheUnit::read (this=0x17268c0, inst=...,
>>> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
>>> at build/ALPHA_SE/cpu/inorder/resources/cache_unit.cc:548
>>> #6 0x00000000007d38f7 in InOrderCPU::read (this=0x172a160, inst=...,
>>> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
>>> at build/ALPHA_SE/cpu/inorder/cpu.cc:1787
>>> #7 0x00000000006d1b11 in InOrderDynInst::readBytes (this=0x26c3250,
>>> addr=4831386496, data=0x7fffffff9a80 "", size=8, flags=0)
>>> at build/ALPHA_SE/cpu/inorder/inorder_dyn_inst.cc:517
>>> #8 0x00000000006d3795 in RefCountingPtr<FaultBase>
>>> InOrderDynInst::read<unsigned long>(unsigned long, unsigned long&, unsigned
>>> int) ()
>>>
>>> Thanks,
>>> Reena
>>>
>>>
>>
>
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