linux-kernel - Re: [PATCH] RISC-V: Enable Zicbom in usermode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241025-puritan-sank-b8a828ef5872@spud>
Date: Fri, 25 Oct 2024 11:16:44 +0100
From: Conor Dooley <conor@...nel.org>
To: Yunhui Cui <cuiyunhui@...edance.com>
Cc: punit.agrawal@...edance.com, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu, cleger@...osinc.com,
	charlie@...osinc.com, evan@...osinc.com, samuel.holland@...ive.com,
	andybnac@...il.com, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RISC-V: Enable Zicbom in usermode

On Fri, Oct 25, 2024 at 05:15:27PM +0800, Yunhui Cui wrote:
> Like Zicboz, by enabling the corresponding bits of senvcfg,
> the instructions cbo.clean, cbo.flush, and cbo.inval can be
> executed normally in user mode.
> 
> Signed-off-by: Yunhui Cui <cuiyunhui@...edance.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 1992ea64786e..bc850518ab41 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -924,7 +924,7 @@ unsigned long riscv_get_elf_hwcap(void)
>  void __init riscv_user_isa_enable(void)
>  {
>  	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICBOZ))
> -		current->thread.envcfg |= ENVCFG_CBZE;
> +		current->thread.envcfg |= ENVCFG_CBIE | ENVCFG_CBCFE | ENVCFG_CBZE;

I believe we previously decided that userspace should not be allowed to
use zicbom, but that not withstanding - this is wrong. It should be
checking for Zicbom, not Zicboz.

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)