On Fri, Oct 7, 2011 at 3:45 AM, rohan puri <[email protected]> wrote:
> > > On Fri, Oct 7, 2011 at 3:51 PM, rohan puri <[email protected]> wrote: > >> >> >> On Fri, Oct 7, 2011 at 3:29 PM, rohan puri <[email protected]>wrote: >> >>> >>> >>> On Fri, Oct 7, 2011 at 12:41 PM, Vaibhav Jain <[email protected]>wrote: >>> >>>> On Thu, Oct 6, 2011 at 9:42 PM, rohan puri <[email protected]>wrote: >>>> >>>>> >>>>> >>>>> On Fri, Oct 7, 2011 at 4:13 AM, Vaibhav Jain <[email protected]>wrote: >>>>> >>>>>> >>>>>> >>>>>> On Thu, Oct 6, 2011 at 11:28 AM, Mulyadi Santosa < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> Hi... >>>>>>> >>>>>>> On Thu, Oct 6, 2011 at 02:34, Vaibhav Jain <[email protected]> >>>>>>> wrote: >>>>>>> > Hi, >>>>>>> > >>>>>>> > I am trying to run a program that scans memory from a given >>>>>>> physical address >>>>>>> > using /dev/mem. >>>>>>> > It uses mmap to map physical address from /dev/mem. So to start >>>>>>> with I used >>>>>>> > /proc/iomem to look up the >>>>>>> > physical memory mapping and found the address 00010000 to be the >>>>>>> starting >>>>>>> > address for System ram. But whenever I >>>>>>> > provide this address to the program it throws an error of >>>>>>> "Operation not >>>>>>> > permitted". >>>>>>> >>>>>>> Probably this could also due to mmap NULL dereferencing protection >>>>>>> (at >>>>>>> least that's how I name it :) ) >>>>>>> >>>>>>> By default, the lowest 65536 byte (10000 in hex) is protected from >>>>>>> mapping etc. It practically render such null dererefencing useless. >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> regards, >>>>>>> >>>>>>> Mulyadi Santosa >>>>>>> Freelance Linux trainer and consultant >>>>>>> >>>>>>> blog: the-hydra.blogspot.com >>>>>>> training: mulyaditraining.blogspot.com >>>>>>> >>>>>> >>>>>> Hi, >>>>>> >>>>>> I tried the same with other addresses (greater than 0x10000 ) also but >>>>>> it is throwing the same error. >>>>>> Is there a way to get over this ? >>>>>> >>>>>> Thanks >>>>>> Vaibhav Jain >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Kernelnewbies mailing list >>>>>> [email protected] >>>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >>>>>> >>>>>> Hi Vaibhav, >>>>> >>>>> This is how it can be done. Refer link >>>>> http://www.theknotter.net/system-memory-dumps-on-linux/ >>>>> >>>>> I have attached the modified code which disables the socket creation >>>>> part and dumps the output in a file. >>>>> >>>>> Regards, >>>>> Rohan Puri >>>>> >>>> >>>> >>>> Thanks Rohan for the code but I already have a code that reads memory >>>> using /dev/mem and mmap. >>>> Only difference is I have to manually change the starting address in >>>> program. The problem is whenver I give >>>> any System RAM address the mmap call fails with 'Operation not >>>> permitted'. I googled a little and found that normally >>>> this operation is not allowed and the kernel has to be compiled with >>>> CONFIG_STRICT_DEVMEM disabled to read any memory >>>> location in this way. I also found out about the boot option >>>> 'strict-devmem =0'. I tried both these options but none of them seems to >>>> working. >>>> So I am trying to figure out if there is some other setting that I need >>>> to change. >>>> I am doing this on Fedora 15 - 2.6.38 kernel. >>>> >>>> Thanks >>>> Vaibhav Jain >>>> >>>> >>> Hi Vaibhav, >>> >>> My iomem file : - >>> >>> 00000000-0000ffff : reserved >>> *00010000-0009f3ff : System RAM* >>> 0009f400-0009ffff : reserved >>> 000c0000-000c7fff : Video ROM >>> 000cc000-000ccfff : Adapter ROM >>> 000cd000-000cffff : pnp 00:0c >>> 000e0000-000effff : pnp 00:0c >>> 000f0000-000fffff : reserved >>> 000f0000-000fffff : System ROM >>> *00100000-cf6dffff : System RAM* >>> 01000000-015dadf2 : Kernel code >>> 015dadf3-01ab907f : Kernel data >>> 01bb1000-01d04fff : Kernel bss >>> >>> Now the program which i sent you, with that I am able to read the 1st >>> part of System RAM successfully. I am getting the operation not permitted >>> error from mmap for second part of System RAM. Can you verify the same on >>> your system. I mean are you able to read the 1st part (if your System RAM is >>> divided) or not ? >>> >>> Regards, >>> Rohan Puri >>> >> >> Another way to get the memory map is install crash module on your system >> and access the memory by accessing the new device /dev/crash instead of >> /dev/mem >> >> Regards, >> Rohan Puri >> > > Even I tried after disabling the option CONFIG_STRICT_DEVMEM, but still > cannot access the 2nd part of System RAM. Also my linux is for x86_64 arch, > hence maybe I am able to access the 1st part of System RAM though that is > above 1 MB. > > Regards, > Rohan Puri > On my system 'cat /proc/iomem' gives the following 00000000-0000ffff : reserved *00010000-0008efff : System RAM* 0008f000-0009ffff : reserved 000a0000-000bffff : PCI Bus 0000:00 000a0000-000bffff : Video RAM area 000c0000-000c7fff : Video ROM 000cd000-000d2dff : Adapter ROM 000d3000-000d53ff : Adapter ROM 000d5800-000d67ff : Adapter ROM 000d6800-000d77ff : Adapter ROM 000e0000-000fffff : reserved 000f0000-000fffff : System ROM *00100000-1f3fffff : System RAM* 00400000-007f0a8f : Kernel code 007f0a90-00a83d3f : Kernel data 00b18000-00bfbfff : Kernel bss 1f400000-1fffffff : RAM buffer 7970b000-797a4fff : ACPI Non-volatile I am unable to access either of System RAM addresses. Both of them give Operation not permitted. Thanks Vaibhav Jain
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