Re: [PATCH 03/23] target/arm: Remove CP_ACCESS_TRAP_UNCATEGORIZED_{EL2, EL3}

[Richard Henderson <richard.henderson@linaro.org>]

On 1/27/23 07:54, Peter Maydell wrote:
> We added the CPAccessResult values CP_ACCESS_TRAP_UNCATEGORIZED_EL2
> and CP_ACCESS_TRAP_UNCATEGORIZED_EL3 purely in order to use them in
> the ats_access() function, but doing so was incorrect (a bug fixed in
> a previous commit).  There aren't any cases where we want an access
> function to be able to request a trap to EL2 or EL3 with a zero
> syndrome value, so remove these enum values.
> 
> As well as cleaning up dead code, the motivation here is that
> we'd like to implement fine-grained-trap handling in
> helper_access_check_cp_reg(). Although the fine-grained traps
> to EL2 are always lower priority than trap-to-same-EL and
> higher priority than trap-to-EL3, they are in the middle of
> various other kinds of trap-to-EL2. Knowing that a trap-to-EL2
> must always for us have the same syndrome (ie that an access
> function will return CP_ACCESS_TRAP_EL2 and there is no other
> kind of trap-to-EL2 enum value) means we don't have to try
> to choose which of the two syndrome values to report if the
> access would trap to EL2 both for the fine-grained-trap and
> because the access function requires it.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
> This isn't just "not used in QEMU"; the architecture doesn't have
> any cases where you need to do this, except for the FPCR/FPSR
> with HCR_TGE case, which we handle in raise_exception() by
> squashing the EC_ADVSIMDFPACCESSTRAP to uncategorized.
> ---
>   target/arm/cpregs.h    | 4 ++--
>   target/arm/op_helper.c | 2 ++
>   2 files changed, 4 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~