On 11/19/19 2:07 PM, Tony Lindgren wrote: > * Andrew F. Davis <afd@xxxxxx> [191119 18:51]: >> On 11/19/19 1:32 PM, Tony Lindgren wrote: >>> It would allow us to completely change over to using >>> arm_smccc_smc() and forget the custom calls. >> >> We would need more than just the r12 quirk to replace all our custom SMC >> handlers, we would need quirks for omap_smc2 which puts process ID in r1 >> and puts #0xff in r6, and omap_smc3 that uses smc #1. All of our legacy >> SMC calls also trash r4-r11, that is very non SMCCC complaint as only >> r4-r7 need be caller saved. I don't see arm_smccc_smc() working with >> legacy ROM no matter how much we hack at it :( > > We would just have omap_smc2() call arm_smccc_smc() and in that > case. And omap_smc2() would still deal with saving and restoring > the registers. > Then why call arm_smccc_smc()? omap_smc2() is already an assembly function, all it needs to do after loading the registers and saving the right ones is issue an "smc #0" instruction, why would we want to instead call into some other function to re-save registers and issue the exact same instruction? > Certainly the wrapper functions calling arm_smccc_smc() can deal > with r12 too if the r12-quirk version and the plain version are > never needed the same time on a booted SoC. > > Are they ever needed the same time on a booted SoC or not? > >> I can make OP-TEE also compatible with the r12 quirk, which is what I >> used to do. That way we didn't need to do any detection. The issue was >> that non-standard SMC calls should not go through the common SMCCC >> handler (unless you are QCOM for some reason..). > > Sounds like for optee nothing must be done for r12 :) > Unless all our calls use the r12 hack, then we would need to fixup OP-TEE to accept that also. Andrew > Regards, > > Tony >
