The StandaloneMm implementation for Arm sets up the stack in
the early startup code using the data section reserved in the
assembly code.
When TF-A loads the StandaloneMM binary in the DRAM it maps
the entire StandaloneMM memory region as Read Only.
Therefore, the initial startup assembly code updates the mem
permissions of the stack region to Read Write.
However, when the StandaloneMmCore is loaded the function
UpdateMmFoundationPeCoffPermissions() starts applying the
memory permissions based on the PE COFF sections as below:
A. If the section is not executable, it first removes the
executable permission of the section by calling TextUpdate().
TextUpdate() is the StandaloneMM MMU library function
ArmSetMemoryRegionNoExec().
B. It then checks if the section is writable, and if it is
it calls ReadWriteUpdater(), which invokes the StandaloneMM
MMU library function ArmClearMemoryRegionReadOnly() to make
the section writable.
However, this results in the stack being made read-only
between A and B. To understand this please see the following
flow.
1. TF-A sets the entire StandaloneMM region as Read Only.
2. The stack is reserved in the data section by the early
assembly entry point code.
+--------------------+ <--- Start of Data Section
| |
| Data Section |
| |
| +----------------+ | <--- Stack region
| | Stack | |
| +----------------+ |
| |
+--------------------+
3. The StanaloneMM early entry point code updates the
attributes of the stack to Read Write.
4. When UpdateMmFoundationPeCoffPermissions() sets the
permission of the data section to remove the Execute
attribute, it calls ArmSetMemoryRegionNoExec().
5. The ArmSetMemoryRegionNoExec() implementation gets the
attributes of the first granule which is at the start
of the data section, then clears the execute permission
and applies the attribute for the entire data section.
6. Since TF-A has mapped the entire section as read only
the first granule of the data section is read only and
therefore the stack region attributes are changed to
Read Only no execute.
7. Since the stack is read only after point A any updates
to the stack result in an exception.
To resolve this issue with update the library with FF-A v1.2,
get/set memory permission per page unit.
Links: https://developer.arm.com/documentation/den0140/latest/ [0]
Signed-off-by: Levi Yun <yeoreum.yun@arm.com>
Introduce a new helper function SpmMmStatusToEfiStatus() to convert
the SPM_MM status values to EFI_STATUS values.
Signed-off-by: Levi yun <yeoreum.yun@arm.com>
Change naming convention in ArmMmSvc.h with
MM to SPM_MM
This would make it clear to discern ABI protocol used to communicate
with secure partition.
Continuous-integration-options: PatchCheck.ignore-multi-package
Signed-off-by: Levi Yun <yeoreum.yun@arm.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3737
Apply uncrustify changes to .c/.h files in the ArmPkg package
Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Andrew Fish <afish@apple.com>
Changes in ArmPkg to prepare building StandaloneMm firmware for
32bit Arm architectures.
Adds ArmmmuStandaloneMmLib library to the list of the standard
components build for ArmPkg on when ARM architectures.
Changes path of source file AArch64/ArmMmuStandaloneMmLib.c
and compile it for both 32bit and 64bit architectures.
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Levi Yun
Michael Kubacki
Etienne Carriere