On 10/30/20 3:28 AM, Etienne Carriere wrote:
On Thu, 29 Oct 2020 at 15:33, Alex G. mr.nuke.me@gmail.com wrote:
On 9/30/20 6:03 PM, Alex G. wrote:
Hi
I'm trying to wrap my head around the purpose of the following lines in ft_system_setup():
if (!CONFIG_IS_ENABLED(OPTEE) || !tee_find_device(NULL, NULL, NULL, NULL)) stm32_fdt_disable_optee(blob);Hi! Me again! Do we have a (good) reason for this, or should I submit a patch to remove this problematic code?
Alex
My interpretation is "if optee is not running, delete the FDT node". The problem is that tee_find_device() invokes device_probe(). This in turn does an SMC call. This call results in an abort and reboot if optee is not running in the first place.
So I don't think that tee_find_device() can be used as a check for "Is optee running?". Exhibit B: Outside of mach-stm32mp, tee_find_device() is used to obtain of a _working_ TEE node, not to ask if "is optee running?".
My problem is that trying to start linux with CONFIG_OPTEE=y will cause the bootm command to crash (log in appendix A):
load mmc 0:7 $fdt_addr_r boot/stm32mp157c-dk2.dtb load mmc 0:7 0xc8000000 boot/utee setenv bootm_boot_mode sec bootm 0xc8000000 - $fdt_addr_rWhat is the intent of calling tee_find_device() in an FDT fixup function?
The scheme is the generic U-Boot implementation do copy OP-TEE related nodes when found in its FDT to the FDT provided to Linux. (called from common/image-fdt.c)
However stm32mp1 can be used with or without OP-TEE installed. To get a generic stm32mp1/U-Boot image that support both configurations (with and w/o OP-TEE installed), U-Boot FDT and config for this plaform do enable OP-TEE but, at u-boot runtime, if we find OP-TEE's not present, we remove the FTD node so that Linux does get it and expect OP-TEE is present.
Do you have any ideas how to make it not crash (short of commenting out the problem lines) ?
The crash seems due to that there is no secure monitor by the time you have this sequence called. Secure monitor is the code that handles the SMC. If none installed, SMCs ends nowhere and likely badly crash the systel. If OP-TEE is not running but there is a secure monitor loaded, it should not crash.
It seems to me that U-Boot does set up a secure monitor for PSCI minimal support, so the U-Boot PSCI stack should nicely handle the SMC to report that there is no OP-TEE installed. Enabling CONFIG_ARMV7_PSCI should fix the issue I think.
Hi Etienne. I understand the reasoning behind this, and I agree that things shouldn't break in theory. However,I just double-checked this with master (7a8ac9df5d). I think we have a bug on our hands:
stm32mp15_basic_defconfig, with the following changes:
CONFIG_TEE=y CONFIG_OPTEE=y CONFIG_OPTEE_TZDRAM_SIZE=0x01000000 # CONFIG_SYSRESET_CMD_POWEROFF is not set
I double-checked that CONFIG_ARMV7_PSCI is indeed set. The following sequence will cause a bad mode abort:
> load mmc 0:7 $loadaddr boot/uImage > load mmc 0:7 $fdt_addr_r boot/stm32mp157c-dk2.dtb > setenv bootargs console=ttySTM0 root=/dev/mmcblk0p7 > bootm $loadaddr - $fdt_addr_r
Alex
Regards, Etienne
Alex
Appendix A: u-boot log after bootm command
## Booting kernel from Legacy Image at c8000000 ... Image Name: Created: 2020-09-28 20:58:56 UTC Image Type: ARM Trusted Execution Environment Kernel Image (uncompressed) Data Size: 349276 Bytes = 341.1 KiB Load Address: fdffffe4 Entry Point: fe000000 Verifying Checksum ... OK Loading Kernel Image ## Flattened Device Tree blob at c4000000 Booting using the fdt blob at 0xc4000000 Loading Device Tree to cffef000, end cffff5e2 ... OK
<BOARD RESETS WITHOUT USER INPUT> U-Boot SPL 2020.10-rc4 (Sep 20 2020 - 23:46:47 +0000) Model: STMicroelectronics STM32MP157C-DK2 Discovery Board