esr_el1

#!/usr/bin/env ruby

# D12.2.36  ESR_EL1, Exception Syndrome Register (EL1)
# page D12-2770

class Accessor
    def initialize(size, value)
        @bits = value.to_s(2).rjust(size, "0").chars.reverse.join
    end

    def [](range)
        return @bits[range].to_i if range.is_a? Integer
        raise "inclusive ranges only" if range.exclude_end?
        raise "use high..low like the ARM docs" if range.begin < range.end
        @bits[range.end..range.begin].chars.reverse.join.to_i 2
    end
end

def ins_data_common(fsc_name, bits)
    fsc = bits[5..0]
    if (set = bits[12..11]) != 0
        puts "SET non-zero"
        puts "unimpl"
        exit 1
    end
    if fsc == 0b010000
        fnv = bits[10]
        if fnv == 0
            puts "FnV: 0b0 -- FAR is valid"
        else
            puts "FnV: 0b1 -- FAR is not valid"
        end
    end
    if (s1ptw = bits[7]) != 0
        puts "S1PTW: 0b1 -- fault on the stage 2 translation of an access for a stage 1 translation table walk"
    end
    puts "#{fsc_name}: 0b#{fsc.to_s(2).rjust(6, "0")}"
    case fsc
    when 0b000000; puts "Address size fault, level 0 of translation or translation table base register."
    when 0b000001; puts "Address size fault, level 1."
    when 0b000010; puts "Address size fault, level 2."
    when 0b000011; puts "Address size fault, level 3."
    when 0b000100; puts "Translation fault, level 0."
    when 0b000101; puts "Translation fault, level 1."
    when 0b000110; puts "Translation fault, level 2."
    when 0b000111; puts "Translation fault, level 3."
    when 0b001001; puts "Access flag fault, level 1."
    when 0b001010; puts "Access flag fault, level 2."
    when 0b001011; puts "Access flag fault, level 3."
    when 0b001101; puts "Permission fault, level 1."
    when 0b001110; puts "Permission fault, level 2."
    when 0b001111; puts "Permission fault, level 3."
    when 0b010000; puts "Synchronous External abort, not on translation table walk."
    when 0b010001; puts "Synchronous Tag Check fail"
    when 0b010100; puts "Synchronous External abort, on translation table walk, level 0."
    when 0b010101; puts "Synchronous External abort, on translation table walk, level 1."
    when 0b010110; puts "Synchronous External abort, on translation table walk, level 2."
    when 0b010111; puts "Synchronous External abort, on translation table walk, level 3."
    when 0b011000; puts "Synchronous parity or ECC error on memory access, not on translation table walk."
    when 0b011100; puts "Synchronous parity or ECC error on memory access on translation table walk, level 0."
    when 0b011101; puts "Synchronous parity or ECC error on memory access on translation table walk, level 1."
    when 0b011110; puts "Synchronous parity or ECC error on memory access on translation table walk, level 2."
    when 0b011111; puts "Synchronous parity or ECC error on memory access on translation table walk, level 3."
    when 0b100001; puts "Alignment fault."
    when 0b110000; puts "TLB conflict abort."
    when 0b110001; puts "Unsupported atomic hardware update fault, if the implementation includes ARMv8.1-TTHM. Otherwise reserved."
    when 0b110100; puts "IMPLEMENTATION DEFINED fault (Lockdown)."
    when 0b110101; puts "IMPLEMENTATION DEFINED fault (Unsupported Exclusive or Atomic access)."
    when 0b111101; puts "Section Domain Fault, used only for faults reported in the PAR_EL1."
    when 0b111110; puts "Page Domain Fault, used only for faults reported in the PAR_EL1."
    end
end

def ins_abort(bits)
    # D12-2790
    ins_data_common("IFSC", bits)
end

def fp_trap_abort(bits)
    cv = bits[24]
    cond = bits[23..20]
    if cv == 1
        puts "COND field valid"
        case cond
        when 0b1110
            puts "taken from AArch64"
        else
            printf "? %04b\n", cond
        end
    else
        puts "COND field invalid"
    end
end

def data_abort(bits)
    # D12-2792
    dfsc = bits[5..0]
    if (isv = bits[24]) == 1
        puts "Instruction syndrome valid"
        puts "unimpl"
        exit 1
    end
    if (vncr = bits[13]) == 1
        puts "VNCR: 0b1 -- fault generated by use of VNCR_EL2, by MRS or MSR at EL1"
    end
    if (cm = bits[8]) != 0
        puts "CM: 0b1 -- data abort generated by cache maintenance/address translation instruction"
    end
    if dfsc != 0b110101 and dfsc != 0b110001
        wnr = bits[6]
        if wnr == 0
            puts "WnR: 0b0 -- abort caused by instruction reading from a memory location"
        else
            puts "WnR: 0b1 -- abort caused by instruction writing to a memory location"
        end
    end
    ins_data_common("DFSC", bits)
end

if ARGV.length == 0
  arg = Integer(`pbpaste`)
  puts "ESR_EL1: 0x#{arg.to_s(16).rjust(16, "0")}"
else
  arg = Integer(ARGV[0])
end

bits = Accessor.new(64, arg)
ec = bits[31..26]
il = bits[25]
iss = bits[24..0]
printf "EC: 0b%06b\n", ec
printf "IL: 0b%b\n", il
printf "ISS: 0b%025b\n", iss
case ec
when 0b000111
    puts "Access to SVE, Advanced SIMD, or floating-point functionality trapped by CPACR_EL1.FPEN, CPTR_EL2.FPEN, CPTR_EL2.TFP, or CPTR_EL3.TFP control."
    fp_trap_abort(bits)
when 0b100001
    puts "Instruction Abort taken without a change in Exception level"
    ins_abort(bits)
when 0b100101
    puts "Data Abort taken without a change in Exception level"
    data_abort(bits)
else
    printf "unimpl EC\n"
    exit 1
end