[PATCH v0 3/3] aarch64: add STEP2 feature and its associated registers

[Richard Earnshaw (lists)]

On 28/06/2024 17:05, Matthieu Longo wrote:
> 
> AArch64 defines new registers for the feature step2 (Enhanced Software Step
> Extension). step2 is an Armv9.5-A feature.
> 
> This patch also adds relevant tests. Regression tested on aarch64-none-elf,
> and no regression found.
> ---
>  .../aarch64/sysreg/armv9_5-a-sysregs-archv9_4-unsupported.l | 6 ++++++
>  gas/testsuite/gas/aarch64/sysreg/armv9_5-a-sysregs.d        | 3 +++
>  gas/testsuite/gas/aarch64/sysreg/armv9_5-a-sysregs.s        | 4 ++++
>  include/opcode/aarch64.h                                    | 3 +++
>  opcodes/aarch64-sys-regs.def                                | 2 ++
>  5 files changed, 18 insertions(+)
> 

+  SYSREG ("id_aa64dfr2_el1",	CPENC (3,0,0,5,2),	F_REG_READ|F_ARCHEXT,	AARCH64_FEATURE (STEP2))

Technically this register previously existed, but was unnamed (it read as zero).  I believe the convention here is to just unconditionally enable it (it shouldn't be gated by the STEP2 feature), similar to the other id_... registers.

R.