From: Quentin Schulz <[email protected]> It is currently possible to build an image with an OP-TEE OS (via the TEE environment variable) without OPTEE_LIB. U-Boot will happily load the TEE OS and the next OS (e.g. the Linux kernel).
This is an issue because on FDT-enabled devices, OP-TEE OS adds nodes to the reserved-memory FDT node for the memory regions it just reserved for itself. This updated is then passed to U-Boot proper which should know better not to use memory from there. The actual issue is that without OPTEE_LIB and OF_LIBFDT enabled, U-Boot proper will not copy those nodes over to the next OS's FDT before starting it. This results in the next OS's (e.g. Linux kernel) to not be aware of reserved memory, incurring random crashes or device reboots when it tries to access secure reserved memory area. Signed-off-by: Quentin Schulz <[email protected]> --- I've just lost a day trying to figure out why my board suddenly boot loops when running a specific program in Linux userspace after updating U-Boot. I actually inadvertently had the TEE environment variable set for a device which doesn't actually need to run any TEE OS (so had OPTEE_LIB disabled). This device is Rockchip PX30-based and the image is built with binman like all Rockchip-based devices. The issue is that I built a U-Boot FIT with an OP-TEE OS that reserves some memory regions for itself (via the TEE environment variable) but U-Boot proper "forgot" to propagate those to the Linux kernel's FDT (because of the missing OPTEE_LIB). Unfortunately, binman doesn't seem to have access to Kconfig symbols (grep CONFIG_ doesn't return anything meaningful and binman is either configured through FDT nodes or via CLI arguments, c.f. cmd_binman in the root Makefile) so I cannot try to be smart and guide the user to the correct Kconfig option to select if TEE is set. I could add a property based on the presence of OPTEE_LIB in rockchip-u-boot.dtsi for example and have a custom message based on that, the issue is that I assume all FDT-based platforms do actually need to do this dance, and not only Rockchip. Another option could be to add a CLI argument to binman through which we would pass the state of OPTEE_LIB and error out the build in that case, but that feels like opening the door to dirty hacks (though this patch is admittedly another dirty hack :) ). Another option is to propagate the TEE environment variable to the preprocessor of the FDT (via dtc_cpp_flags) and then I can do #if defined(TEE) && !IS_ENABLED(CONFIG_OPTEE_LIB) #error "CONFIG_OPTEE_LIB must be enabled!" #endif but we have the same issue as above, it is then Rockchip specific and also feels bad. Another option is to remove the @tee-SEQ node from the binman FIT description when OPTEE_LIB isn't set but then I would lose the nice message when no TEE is provided: Image 'simple-bin' is missing optional external blobs but is still functional: tee-os and even worse, build without any TEE OS even though I could provide one with the TEE environment variable. Finally, another option could be to move this hack under arch/arm/mach-rockchip/Kconfig to make it Rockchip specific or add a depends on ARCH_ROCKCHIP OP-TEE OS on Aarch32 Rockchip boards doesn't actually need any of that if SPL_OPTEE_IMAGE is set because arch/arm/mach-rockchip/sdram.c then marks some hardcoded memory regions in RAM as holes in DRAM, which has the same effect as reserved memory regions I guess. I assume other platforms may use something different, so it may be casting too wide of a net. Does anyone have something more delicate than this sledgehammer of a solution? --- lib/optee/Kconfig | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/lib/optee/Kconfig b/lib/optee/Kconfig index e6834d4d3e1fe700d15ae57984ccc2716955ba2d..34b9d8afe675c5aa2aa2122e6716eda1697e3898 100644 --- a/lib/optee/Kconfig +++ b/lib/optee/Kconfig @@ -4,6 +4,25 @@ config OPTEE_LIB help Selecting this option will enable the shared OPTEE library code. +config HAS_TEE_IN_BUILD_ENV + def_bool $(success, test -n "$(TEE)") + select OPTEE_LIB if OF_CONTROL + select OF_LIBFDT if OF_CONTROL + help + It is typical whenever OP-TEE OS is loaded before U-Boot proper that + it modifies the FDT passed to U-Boot proper to add reserved-memory + nodes for the RAM it just reserved for itself. + + U-Boot must copy those reserved-nodes in the FDT for the next OS to + boot. + + Failing to do so will incur random crashes or device reboots once the + next OS is running. + + This makes sure that whenever TEE is present in the environment, + meaning a TEE OS will be part of the boot flow, the copy made by the + OP-TEE lib will happen. + config OPTEE_IMAGE bool "Support OPTEE images" help --- base-commit: f28891d444631c91a6e090927486a2169b51b20f change-id: 20250919-tee-env-needs-optee-lib-32e0a3cec838 Best regards, -- Quentin Schulz <[email protected]>
