Data Communication btw Normal and Secure World in IMX53_QSB

[Martin Stein]

Hi Jaemin,

Without going deeper into your specific problem, I'd like to suggest you
to have a look at my working branches [1] that concern with issue [2].
They show a working implementation of shared-mem communication between
secure and non-secure world. The interesting parts in your case are:

* Mapping of the buffer in file [3] in line 422. Note that we create a
pseudo-device struct for that in line 406. This struct isn't related to
any real device and is merely needed because dma_alloc_coherent must
know from which DMA pool to allocate with which parameters.

* Registration of the buffer in file [3] via function genblk_smc_buffer

* Secure to non-secure communication in file [3] in genblk_smc_name.
Secure back-end in file [4] in Vm::smc_blk_name.

* Non-secure to secure communication in file [3] in genode_blk_request
if argument write=true. Secure back-end in file [4] in
Vm::smc_blk_submit the call to blk_buf_to_pkt.

Please be aware that - although it works on hardware - this code is
still in progress and should not be considered as final solution. If you
have further questions, don't hesitate to ask ;)

Cheers,
Martin

[1]
https://github.com/m-stein/genode/tree/1497_usb_armory_demo
https://github.com/m-stein/linux/tree/1497_usb_armory_demo

[2]
https://github.com/genodelabs/genode/issues/1497

[3] <LINUX>/drivers/block/genode_block.c

[4] <GENODE>/repos/os/src/server/tz_vmm/usb_armory/vm.h

On 14.07.2015 11:00, JaeminPark wrote:
> I’m currently developing a simple trustzone device driver running in
> Normal World to communicate with Genode in Secure World.
> I’m using IMX53 QSB,  Genode 15.02 as Secure OS, and customized Linux as
> OS for Normal World.
> 
> In Normal World, my simple device driver calls */smc/* instruction
> inside */module_init()/*.
> The instruction is invoked with the command structure (named by
> “*/struct smc_cmd/*”).
> The physical address of "struct smc_cmd" is passing to Genode via
> */_vm->state()->r1/*.
> There exists two physical addresses inside “struct smc_cmd": one for
> request buffer and the other for response buffer where the response
> buffer is allocated by */kzalloc()/*.
> For the address conversion, I used /*virt_to_phys()*/.
> 
> In Secure World (Genode),  I’m modifying the */tz_vmm /*source code for
> this experiment. 
> I’m succeed in reading the request buffer from Normal World by directly
> accessing the physical address of the request buffer :
> 
> *PINF("req_buf = %s (0x%x)", (char*)((struct
> smc_cmd*)cmd_addr)->req_buf_phys, ((struct
> smc_cmd*)cmd_addr)->req_buf_phys);*
> 
> Ridiculously and Unfortunately, I’m in trouble to write some characters
> in response buffer (whose address is the physical address of Normal World).
> I used */Genode::memcpy()/* to write the characters as follows where
> */cmd_addr/* is the physical address of the command structure passed
> from Normal World :
> 
> *//* acquire data to be written into memory space of normal world *//*
> */        Genode::memcpy(tmp, (const char*) "From Secure World",
> strlen("From Secure World"));/*
> */        tmp[17] = '\0';/*
> */
> /*
> */        /* write a data into resp_buf_phys *//*
> */Genode::memcpy((char*)((struct smc_cmd*)cmd_addr)->resp_buf_phys,
> (const char*) tmp, sizeof(tmp));/*
> */
> /*
> */        /* printout contents of memory for debug *//*
> */        PINF("res_buf = %s (0x%x)", (char*)((struct
> smc_cmd*)cmd_addr)->resp_buf_phys, ((struct
> smc_cmd*)cmd_addr)->resp_buf_phys);/*
> 
> It seems that the writing operation in Secure World is successful since
> the last PINF() shows me the “From Secure World” in console.
> 
> However, when I read the address (converted from the physical address
> using */phys_to_virt()/*) in my device driver, I can only see the empty
> string (initial status).
> 
> My questions are :
> 
>   * Do I need another approach to write the physical memory of Normal
>     World in the side of Genode?
>   * Is there any simple example or any volunteer to share an example for
>     this kind of operation?
>   * Is there any comment to implement this kind of example?
> 
> 
> 
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