Re: [PATCH] arm64: traps: Add a macro to simplify the condition codes check

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 20/03/26 1:58 PM, Jinjie Ruan wrote:
> Add DEFINE_COND_CHECK macro to define the simple __check_* functions
> to simplify the condition codes check.
> 
> No functional changes.
> 
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/traps.c | 59 ++++++++++-----------------------------
>  1 file changed, 15 insertions(+), 44 deletions(-)
> 
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 914282016069..6216fe9e8e42 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -49,45 +49,21 @@
>  #include <asm/system_misc.h>
>  #include <asm/sysreg.h>
>  
> -static bool __kprobes __check_eq(unsigned long pstate)
> -{
> -	return (pstate & PSR_Z_BIT) != 0;
> -}
> -
> -static bool __kprobes __check_ne(unsigned long pstate)
> -{
> -	return (pstate & PSR_Z_BIT) == 0;
> -}
> -
> -static bool __kprobes __check_cs(unsigned long pstate)
> -{
> -	return (pstate & PSR_C_BIT) != 0;
> -}
> -
> -static bool __kprobes __check_cc(unsigned long pstate)
> -{
> -	return (pstate & PSR_C_BIT) == 0;
> -}
> -
> -static bool __kprobes __check_mi(unsigned long pstate)
> -{
> -	return (pstate & PSR_N_BIT) != 0;
> -}
> -
> -static bool __kprobes __check_pl(unsigned long pstate)
> -{
> -	return (pstate & PSR_N_BIT) == 0;
> -}
> -
> -static bool __kprobes __check_vs(unsigned long pstate)
> -{
> -	return (pstate & PSR_V_BIT) != 0;
> -}
> -
> -static bool __kprobes __check_vc(unsigned long pstate)
> -{
> -	return (pstate & PSR_V_BIT) == 0;
> -}
> +#define DEFINE_COND_CHECK(name, flag, expected)			\
> +static bool __kprobes __check_##name(unsigned long pstate)	\
> +{								\
> +	return ((pstate & (flag)) != 0) == (expected);		\
> +}
> +
> +DEFINE_COND_CHECK(eq, PSR_Z_BIT, true)
> +DEFINE_COND_CHECK(ne, PSR_Z_BIT, false)
> +DEFINE_COND_CHECK(cs, PSR_C_BIT, true)
> +DEFINE_COND_CHECK(cc, PSR_C_BIT, false)
> +DEFINE_COND_CHECK(mi, PSR_N_BIT, true)
> +DEFINE_COND_CHECK(pl, PSR_N_BIT, false)
> +DEFINE_COND_CHECK(vs, PSR_V_BIT, true)
> +DEFINE_COND_CHECK(vc, PSR_V_BIT, false)
> +DEFINE_COND_CHECK(al, 0, false)		/* Always true */

	(((pstate & 0 == 0) != 0) == false) ---> return true 

Although this looks OK but wondering if __check_al() should
be left unchanged for simplicity. OR could all its call sites
be changed assuming an unconditional 'true' return thus later
__check_al() can be dropped.

>  
>  static bool __kprobes __check_hi(unsigned long pstate)
>  {
> @@ -131,11 +107,6 @@ static bool __kprobes __check_le(unsigned long pstate)
>  	return (temp & PSR_N_BIT) != 0;
>  }
>  
> -static bool __kprobes __check_al(unsigned long pstate)
> -{
> -	return true;
> -}
> -
>  /*
>   * Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that
>   * it behaves identically to 0b1110 ("al").