From: Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: arm64: populate hwcaps from ID_AA64ISAR0
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: tech@openbsd.org
Date: Wed, 17 Jul 2024 16:58:50 +0200

> Date: Tue, 16 Jul 2024 22:10:26 +0200
> From: Christian Weisgerber <naddy@mips.inka.de>
> 
> The patch below populates arm64 hwcaps from the ID_AA64ISAR0 register.
> 
> I didn't look at other registers and I don't know if we want to do
> it this way.  There is the question of keeping this in sync with
> the CPU_ID_AA64* sysctl() for filtering out unsupported options.
> 
> It's intended as a provisional change to signal the common AES,
> SHA, CRC32 instruction extensions via elf_aux_info(), so people can
> check how that interacts with ports.

Sorry, but I discussed with jca@ that we (I) would tackle this after
my diff goes in that adds emulation of the ID registers as that
reorganizes how thie cpi_id_aa64xxx registers are sanitized.

We want to set the hwcap flags at that point instead of in
cpu_identify().

> -----------------------------------------------
> commit ebba40aebdc3568b1e6bc72a492f8d8b7fb3e1a3 (local)
> from: Christian Weisgerber <naddy@mips.inka.de>
> date: Tue Jul 16 20:02:15 2024 UTC
>  
>  arm64: provisionally populate hwcaps with ID_AA64ISAR0 register
>  
> diff 9982db7b2eb53fd996e16d3eea6e03b5353a2d91 ebba40aebdc3568b1e6bc72a492f8d8b7fb3e1a3
> commit - 9982db7b2eb53fd996e16d3eea6e03b5353a2d91
> commit + ebba40aebdc3568b1e6bc72a492f8d8b7fb3e1a3
> blob - 69898059074417a146f80b96d4afe6d29bf354ae
> blob + a1b35356ea69053870e6beee361a2738885ba9b6
> --- sys/arch/arm64/arm64/cpu.c
> +++ sys/arch/arm64/arm64/cpu.c
> @@ -692,6 +692,7 @@ cpu_identify(struct cpu_info *ci)
>  		printf("%sRNDR", sep);
>  		sep = ",";
>  		arm64_has_rng = 1;
> +		hwcap2 |= HWCAP2_RNG;
>  	}
>  
>  	if (ID_AA64ISAR0_TLB(id) >= ID_AA64ISAR0_TLB_IOS) {
> @@ -704,38 +705,47 @@ cpu_identify(struct cpu_info *ci)
>  	if (ID_AA64ISAR0_TS(id) >= ID_AA64ISAR0_TS_BASE) {
>  		printf("%sTS", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_FLAGM;
>  	}
> -	if (ID_AA64ISAR0_TS(id) >= ID_AA64ISAR0_TS_AXFLAG)
> +	if (ID_AA64ISAR0_TS(id) >= ID_AA64ISAR0_TS_AXFLAG) {
>  		printf("+AXFLAG");
> +		hwcap2 |= HWCAP2_FLAGM2;
> +	}
>  
>  	if (ID_AA64ISAR0_FHM(id) >= ID_AA64ISAR0_FHM_IMPL) {
>  		printf("%sFHM", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_ASIMDFHM;
>  	}
>  
>  	if (ID_AA64ISAR0_DP(id) >= ID_AA64ISAR0_DP_IMPL) {
>  		printf("%sDP", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_ASIMDDP;
>  	}
>  
>  	if (ID_AA64ISAR0_SM4(id) >= ID_AA64ISAR0_SM4_IMPL) {
>  		printf("%sSM4", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_SM4;
>  	}
>  
>  	if (ID_AA64ISAR0_SM3(id) >= ID_AA64ISAR0_SM3_IMPL) {
>  		printf("%sSM3", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_SM3;
>  	}
>  
>  	if (ID_AA64ISAR0_SHA3(id) >= ID_AA64ISAR0_SHA3_IMPL) {
>  		printf("%sSHA3", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_SHA3;
>  	}
>  
>  	if (ID_AA64ISAR0_RDM(id) >= ID_AA64ISAR0_RDM_IMPL) {
>  		printf("%sRDM", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_ASIMDRDM;
>  	}
>  
>  	if (ID_AA64ISAR0_ATOMIC(id) >= ID_AA64ISAR0_ATOMIC_IMPL) {
> @@ -751,18 +761,23 @@ cpu_identify(struct cpu_info *ci)
>  	if (ID_AA64ISAR0_CRC32(id) >= ID_AA64ISAR0_CRC32_BASE) {
>  		printf("%sCRC32", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_CRC32;
>  	}
>  
>  	if (ID_AA64ISAR0_SHA2(id) >= ID_AA64ISAR0_SHA2_BASE) {
>  		printf("%sSHA2", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_SHA2;
>  	}
> -	if (ID_AA64ISAR0_SHA2(id) >= ID_AA64ISAR0_SHA2_512)
> +	if (ID_AA64ISAR0_SHA2(id) >= ID_AA64ISAR0_SHA2_512) {
>  		printf("+SHA512");
> +		hwcap |= HWCAP_SHA512;
> +	}
>  
>  	if (ID_AA64ISAR0_SHA1(id) >= ID_AA64ISAR0_SHA1_BASE) {
>  		printf("%sSHA1", sep);
>  		sep = ",";
> +		hwcap |= HWCAP_SHA1;
>  	}
>  
>  	if (ID_AA64ISAR0_AES(id) >= ID_AA64ISAR0_AES_BASE) {
> @@ -771,9 +786,12 @@ cpu_identify(struct cpu_info *ci)
>  #ifdef CRYPTO
>  		arm64_has_aes = 1;
>  #endif
> +		hwcap |= HWCAP_AES;
>  	}
> -	if (ID_AA64ISAR0_AES(id) >= ID_AA64ISAR0_AES_PMULL)
> +	if (ID_AA64ISAR0_AES(id) >= ID_AA64ISAR0_AES_PMULL) {
>  		printf("+PMULL");
> +		hwcap |= HWCAP_PMULL;
> +	}
>  
>  	/*
>  	 * ID_AA64ISAR1
> 
> -- 
> Christian "naddy" Weisgerber                          naddy@mips.inka.de
> 
>