Hi Alex,
On Wed, 4 Nov 2020 at 20:55, Alex G. mr.nuke.me@gmail.com wrote:
On 11/4/20 1:07 AM, Etienne Carriere wrote:
On Tue, 3 Nov 2020 at 16:53, Alex G. mr.nuke.me@gmail.com wrote:
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);
Here (in mach-stm32mp/fdt.c), maybe to skip runtime probe when built for SPL.
+ if (!CONFIG_IS_ENABLED(SPL_BUILD) && (!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=0x01000000My apologies, I did'nt notice you use the _basic_defconfig. With this defconfig, U-Boot cannot invoke OP-TEE services since OP-TEE is booted only once U-Boot execution is completed (once bootm command jumps to OP-TEE boot entry). So in this config U-Boot cannot find the OP-TEE node.
Maybe ft_system_setup() (mach-stm32mp/fdt.c) should bypass OP-TEE auto probing when CONFIG_BOOTM_OPTEE is enabled.
I'm seeing the following premise: (a) Start out with a "clean" devicetree (b) Add the 'optee' node (generic code) (c) Remove the 'optee' node (stm32mp1 specific)
This seems odd to me for two reasons: 1. The code does more work than it needs to 2. stm32mp behaves differently than other platforms
The way I would approach this is to adjust the heuristic in step (b). This can be found in include/tee/optee.h:
if CONFIG_OPTEE and CONFIG_OF_LIBFDT add optee node else do nothingIf there's no need to do step (b), why do both steps (b) and (c) instead of doing nothing?
Given that there isn't a situation where step (c) makes sense, I propose that we remove stm32_fdt_disable_optee() entirely. The worst case is that the 'optee' node stays up, linux is booted in non-secure mode, and throws an -ENODEV in optee_probe() -- but otherwise the system boots.
I can prepare a patch, pending Patrick's analysis.
Ack.
That would probably require to change stm32mp15_trusted_defconfig to explicitly disable CONFIG_BOOTM_OPTEE, since this config does not allow booting OP-TEE from U-Boot.
Patrick, your opinion?
FYI Alex, stm32mp15_basic_defconfig is not well suited to boot OP-TEE. Consider using stm32mp15_trusted_defconfig instead. The "Trusted" means U-Boot is booted after secure world. SPL could still be used to load/boot OP-TEE but stm32mp15_trusted_defconfig does not provide such support in current U-Boot. TF-A is an alternative to SPL in this case.
I have boot timing constraint of one to a graphical userspace application. The TF-A boot flow blows my boot time budget. I think trusted_defconfig assumes TF-A instead of SPL, so I didn't dig into it.
Ok. I agree it should work.
The fast graphical boot is a use case that I don't think has been addressed for STM32MP. I'm currently implementing:
SPL -> OPTEE -> Linux -> Userspace graphics appThis flow doesn't really require CONFIG_BOOTM_OPTEE. However, I'm still interested in a proper for the sake of consistency across platforms.
mach-stm32mp/fdt.c could be changed to not probe OP-TEE when it is built as SPL. SPL would then still enable optee nodes in kernel DT when found enabled in U-Boot FDT from generic path. stm32mp15 would still leverage SMCCC protocol to identify OP-TEE presence dynamically.
If I understand correctly, U-Boot generic adds OP-TEE nodes in kernel FDT when OP-TEE is found in FDT (upon fe contidions: optee node found and status="okay" in u-boot FDT, no optee node already in kernel FDT) It looks a good behaviour.
stm32mp15 leverage U-Boot can probe OP-TEE to dynamically check whether OP-TEE is really installed and prevent booted kernel failure/trace on OP-TEE absence. It makes stm32mp15 U-Boot DTS files more flexible when the target board runs or not an OP-TEE. Obviously this dynamic test cannot be run from SPL.
br/ etienne
Alex
br, etienne
# CONFIG_SYSRESET_CMD_POWEROFF is not setI 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_rAlex
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