Re: [Qemu-devel] [PATCH v8 03/27] target-arm: add banked register accessors

[Peter Maydell <peter.maydell@linaro.org>]

On 30 October 2014 21:28, Greg Bellows <greg.bellows@linaro.org> wrote:
> From: Fabian Aggeler <aggelerf@ethz.ch>
>
> If EL3 is in AArch32 state certain cp registers are banked (secure and
> non-secure instance). When reading or writing to coprocessor registers
> the following macros can be used.
>
> - A32_BANKED macros are used for choosing the banked register based on provided
>   input security argument.  This macro is used to choose the bank during
>   translation of MRC/MCR instructions that are dependent on something other
>   than the current secure state.
> - A32_BANKED_CURRENT macros are used for choosing the banked register based on
>   current secure state.  This is NOT to be used for choosing the bank used
>   during translation as it breaks monitor mode.
>
> If EL3 is operating in AArch64 state coprocessor registers are not
> banked anymore. The macros use the non-secure instance (_ns) in this
> case, which is architecturally mapped to the AArch64 EL register.
>
> Signed-off-by: Sergey Fedorov <s.fedorov@samsung.com>
> Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
> Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> ---
>
> v7 -> v8
> - Move use_secure_reg() function to the TBFLAG patch.
>
> v5 -> v6
> - Converted macro USE_SECURE_REG() into inlince function use_secure_reg()
> - Globally replace Aarch# with AArch#
>
> v4 -> v5
> - Cleaned-up macros to try and alleviate misuse.  Made A32_BANKED macros take
>   secure arg indicator rather than relying on USE_SECURE_REG.  Incorporated the
>   A32_BANKED macros into the A32_BANKED_CURRENT.  CURRENT is now the only one
>   that automatically chooses based on current secure state.
> ---
>  target-arm/cpu.h | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index be5d022..5117d4d 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -817,6 +817,33 @@ static inline bool arm_el_is_aa64(CPUARMState *env, int el)
>      return arm_feature(env, ARM_FEATURE_AARCH64);
>  }
>
> +/* Macros for accessing a specified CP register bank */
> +#define A32_BANKED_REG_GET(_env, _regname, _secure)    \
> +    ((_secure) ? (_env)->cp15._regname##_s : (_env)->cp15._regname##_ns)
> +
> +#define A32_BANKED_REG_SET(_env, _regname, _secure, _val)   \
> +    do {                                                \
> +        if (_secure) {                                   \
> +            (_env)->cp15._regname##_s = (_val);            \
> +        } else {                                        \
> +            (_env)->cp15._regname##_ns = (_val);           \
> +        }                                               \
> +    } while (0)

It's just occurred to me that this probably needs to be doing
a deposit32(), because where an AArch32 register is architecturally
mapped to an AArch64 register then only the appropriate 32 bits
of the AArch64 reg get modified by setting the 32 bit value.

> +/* Macros for automatically accessing a specific CP register bank depending on
> + * the current secure state of the system.  These macros are not intended for
> + * supporting instruction translation reads/writes as these are dependent
> + * solely on the SCR.NS bit and not the mode.
> + */
> +#define A32_BANKED_CURRENT_REG_GET(_env, _regname)        \
> +    A32_BANKED_REG_GET((_env), _regname,                \
> +                       ((!arm_el_is_aa64((_env), 3) && arm_is_secure(_env))))
> +
> +#define A32_BANKED_CURRENT_REG_SET(_env, _regname, _val)                       \
> +    A32_BANKED_REG_SET((_env), _regname,                                    \
> +                       ((!arm_el_is_aa64((_env), 3) && arm_is_secure(_env))),  \
> +                       (_val))
> +
>  void arm_cpu_list(FILE *f, fprintf_function cpu_fprintf);
>  unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx);

-- PMM