On 02/25/13 12:02, Russell King - ARM Linux wrote: > > This can of worms is getting bigger. We have more problems with our > handling of the different VFP versions, specifically the handling of > the EX=0 DEX=0 case. > > VFP common subarch 3 defines the EX=0, DEX=0 encoding to mean one of > the following conditions have been met: > > 1. an unallocated VFP instruction was encountered. > > In other words, the VFP was the target of the co-processor instruction, > but the instruction is not a known VFP instruction encoding. This > should raise an undefined instruction exception. > > 2. an allocated VFP instruction was encountered, but not handled in > hardware. > > In other words, the instruction is a valid VFP instruction, but the > hardware has opted not to implement this instruction and wants > software to emulate it instead. > > (Note: this can also be raised as EX=0, DEX=1 - implementation > defined!) > [snip] > > So, if EX or DEX is set, _or_ IXE is set, we pass control to VFP_bounce. > This is problematical. > > (a) condition (2) above isn't correctly handled for common subarch v3 - it > is always treated as an undefined instruction, and will result in a > SIGILL being delivered. > [snip] > > Now, (a) is just bad behaviour - as we haven't had any reports of this > yet, I suspect that no one has implemented VFP hardware with this > behaviour yet. I believe we ran into this a while ago and fixed it for our chips. We never sent the patch upstream. Sorry. https://www.codeaurora.org/gitweb/quic/la/?p=kernel/msm.git;a=commitdiff;h=00a13be874f230159a6b7f8cc9d0ff23bc1b7d05 I'm looking into what our bits correspond to. Hopefully get back to you in 20 something hours. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
