Thanks David.

Compiler optimization seems to be a valid case, but it is interesting to note that although we can have W only pages, we cannot do it because of compiler optimizations.

I changed mapping to map output param to RW,  more test cases pass this time :)

However, If I map input param to R only, few test cases still fail.

I do not think multiple parameters can share the same page.

The shared buffer allocated by linux tee-driver is always page aligned: https://github.com/linaro-swg/linux/blob/optee/drivers/tee/tee_shm_pool.c#L126

and linux kernel api will always allocate a different shared buffer for each of the parameter:

https://github.com/OP-TEE/optee_client/blob/master/libteec/src/tee_client_api.c#L144

Also, I checked the failing test cases (ex: 1011) , I do not see anything wrong.

On TEE side, I expected to see an abort and put a break point in abort handler, but it is never hit.

---

From: David Brown <david.brown@linaro.org>
Sent: Monday, June 20, 2016 7:13:05 AM
To: machiry aravind; tee-dev@lists.linaro.org
Subject: Re: [Tee-dev] OPTEE OS : Param type not respected in mapping

 

I'm curious what happens if you try using RW for output as well. The compiler will sometimes need to read data in order to write to it.

I guess the other concern I'd have, without looking at it too much, is there a case where multiple parameters share the same page?

David

On Mon, Jun 20, 2016 at 12:12 AM machiry aravind <machiry_msidc@hotmail.com> wrote:

Hi all,

In optee-os, memory of all params is mapped RW, irrespective of paramType (viz, INPUT, OUTPUT or INOUT).

References:

https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/mm/tee_mmu.c#L394 and

https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/mm/tee_mmu.c#L62

Do we know why is this so?

I tried to change this to map R only for input, W for output and RW for inout.

However few tests (ex: 4001 - 4007) in xtest suite fails.

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