On 2/28/24 03:27, Zhiguang Liu wrote:
> In last patch, we add code support to unregister MMI handler inside
> itself. However, the code doesn't support unregister MMI handler
> insider other MMI handler. While this is not a must-have usage.
> So add check to disallow unregister MMI handler in other MMI handler.
>
> Cc: Liming Gao <gaolim...@byosoft.com.cn>
> Cc: Jiaxin Wu <jiaxin...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
> Cc: Sami Mujawar <sami.muja...@arm.com>
> Cc: Ray Ni <ray...@intel.com>
> Signed-off-by: Zhiguang Liu <zhiguang....@intel.com>
> ---
> StandaloneMmPkg/Core/Mmi.c | 35 ++++++++++++++++++++++++++---------
> 1 file changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/StandaloneMmPkg/Core/Mmi.c b/StandaloneMmPkg/Core/Mmi.c
> index c1a1d76e85..54794c6b3d 100644
> --- a/StandaloneMmPkg/Core/Mmi.c
> +++ b/StandaloneMmPkg/Core/Mmi.c
> @@ -36,8 +36,9 @@ typedef struct {
> MMI_ENTRY *MmiEntry;
> } MMI_HANDLER;
>
> -LIST_ENTRY mRootMmiHandlerList = INITIALIZE_LIST_HEAD_VARIABLE
> (mRootMmiHandlerList);
> -LIST_ENTRY mMmiEntryList = INITIALIZE_LIST_HEAD_VARIABLE
> (mMmiEntryList);
> +LIST_ENTRY mRootMmiHandlerList = INITIALIZE_LIST_HEAD_VARIABLE
> (mRootMmiHandlerList);
> +LIST_ENTRY mMmiEntryList = INITIALIZE_LIST_HEAD_VARIABLE
> (mMmiEntryList);
> +MMI_HANDLER *gCurrentMmiHandler = NULL;
>
> /**
> Finds the MMI entry for the requested handler type.
> @@ -161,13 +162,19 @@ MmiManage (
> // get next node before handler is executed, since LIST_ENTRY that
> // Link points to may be freed if unregister MMI handler.
> //
> - Link = Link->ForwardLink;
> - Status = MmiHandler->Handler (
> - (EFI_HANDLE)MmiHandler,
> - Context,
> - CommBuffer,
> - CommBufferSize
> - );
> + Link = Link->ForwardLink;
> + //
> + // Assign gCurrentMmiHandle before calling the MMI handler and
> + // set to NULL when it returns.
> + //
> + gCurrentMmiHandler = MmiHandler;
> + Status = MmiHandler->Handler (
> + (EFI_HANDLE)MmiHandler,
> + Context,
> + CommBuffer,
> + CommBufferSize
> + );
> + gCurrentMmiHandler = NULL;
>
> switch (Status) {
> case EFI_INTERRUPT_PENDING:
> @@ -314,6 +321,16 @@ MmiHandlerUnRegister (
> return EFI_INVALID_PARAMETER;
> }
>
> + //
> + // Check if unregister MMI handler inside a MMI Handler
> + //
> + if (gCurrentMmiHandler != NULL) {
> + //
> + // Only allow to unregister MMI Handler inside itself.
> + //
> + ASSERT (gCurrentMmiHandler == MmiHandler);
> + }
> +
> MmiEntry = MmiHandler->MmiEntry;
>
> RemoveEntryList (&MmiHandler->Link);
same comment as for patch#2
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