Re: [edk2-devel] [PATCH v2 1/1] ArmPkg: Fix uninitialised variable in ArmMmuStandaloneMmLib

["Sughosh Ganu" <sughosh.ganu@linaro.org>]

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On Thu, 25 Feb 2021 at 22:41, Sami Mujawar <sami.mujawar@arm.com> wrote:

> The following patches added support for StandaloneMM using FF-A:
> 9da5ee116a28 ArmPkg: Allow FF-A calls to set memory region's attributes
> 0e43e02b9bd8 ArmPkg: Allow FF-A calls to get memory region's attributes
>
> However, in the error handling logic for the Get/Set Memory attributes,
> the CLANG compiler reports that a status variable could be used without
> initialisation. This issue is a false positive and is not seen with GCC.
>
> The Get/Set Memory attributes operation is atomic and therefore an
> FFA_INTERRUPT or FFA_SUCCESS response is not expected in response
> to FFA_MSG_SEND_DIRECT_REQ. So the remaining cases that could occur
> are:
>  - the target sends FFA_MSG_SEND_DIRECT_RESP with a success or
>    failure code.
>  or
>  - FFA_MSG_SEND_DIRECT_REQ transmission failure.
>
> Therefore,
>  - reorder the error handling conditions such that it prevents the
>    uninitialised variable issue being flagged by CLANG.
>  - move the repetitive code to a static helper function and add
>    documentation at the appropriate places.
>  - fix error handling in functions that invoke GetMemoryPermissions().
>
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> ---
> The changes can be seen at:
> https://github.com/samimujawar/edk2/tree/1657_stmm_ffa_fix_unused_var_v2


 Tested the changes on the StandaloneMm image on the Qemu platform.

Tested-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Sughosh Ganu <sughosh.ganu@linaro.org>

-sughosh

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