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CA72 can't access ICC_IAR1_EL1 at EL1

Kael Hong

I can access ICC_IAR1_EL1 at EL3 using SP_EL0, however, after I switch EL3 to EL1 non-secure, I can't read IIC_IAR1_EL1 anymore, which doesn't make sense. 

Can anybody help here? much appreciated.  

__func__011000 EC=MSR, MRS, or System instruction, that isn't reported using EC 0x00/0x01/0x07Unhandled exception 0x18(24) from CA72_0 to CA72_0
EXC number:0x00000018
EXC class: 0x00000018
FaultReg: 0x00000000
StatusPrg: 0x80000005
PC: 0x00000000 0xA0007F78
FaultReg: 0xD538CC00
StatusPrg: 0x00303019
Exception class is MSR_MRS
These report exceptions from MSR, MRS, or System instructions
Instruction syndrome MSR/MRS:
Op0: 0x00000000
Op2: 0x00000000
Op1: 0x00000000
CRn: 0x00000000
Rt : 0x00000000
CRm: 0x00000018
dir: 0x00000001

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  • 0 Arm Employee Badge in reply to Kael Hong

    Hmm, interesting.

    A few questions then:

    • Are you setting up ICC_SRE_EL2.SRE before ICC_SRE_EL1(NS)?
    • Do you have ISBs between changing SCR_EL3.NS and accessing the different ICC_SRE_EL1s?
    • To which EL is the exception being taken? (I was assuming EL1!)
      • If it's being taken to EL2, you also need to check how ICH_HCR_EL2.TALL1 is configured.
    • The Op0/Op1/Op2/CRn/CRm values reported don't match ICC_IAR1_EL1.  Have you sanity checked that's the instruction actually being executed?
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  • 0 Arm Employee Badge in reply to Kael Hong

    Hmm, interesting.

    A few questions then:

    • Are you setting up ICC_SRE_EL2.SRE before ICC_SRE_EL1(NS)?
    • Do you have ISBs between changing SCR_EL3.NS and accessing the different ICC_SRE_EL1s?
    • To which EL is the exception being taken? (I was assuming EL1!)
      • If it's being taken to EL2, you also need to check how ICH_HCR_EL2.TALL1 is configured.
    • The Op0/Op1/Op2/CRn/CRm values reported don't match ICC_IAR1_EL1.  Have you sanity checked that's the instruction actually being executed?
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