linux-kernel - Re: [PATCH Part2 RFC v4 08/40] x86/traps: Define RMP violation #PF error code

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <YPCGVKESqZFWwdyB@google.com>
Date:   Thu, 15 Jul 2021 19:02:44 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>, tony.luck@...el.com,
        npmccallum@...hat.com, brijesh.ksingh@...il.com
Subject: Re: [PATCH Part2 RFC v4 08/40] x86/traps: Define RMP violation #PF
 error code

On Wed, Jul 07, 2021, Brijesh Singh wrote:
> Bit 31 in the page fault-error bit will be set when processor encounters
> an RMP violation.
> 
> While at it, use the BIT() macro.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/include/asm/trap_pf.h | 18 +++++++++++-------
>  arch/x86/mm/fault.c            |  1 +
>  2 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/include/asm/trap_pf.h b/arch/x86/include/asm/trap_pf.h
> index 10b1de500ab1..29f678701753 100644
> --- a/arch/x86/include/asm/trap_pf.h
> +++ b/arch/x86/include/asm/trap_pf.h
> @@ -2,6 +2,8 @@
>  #ifndef _ASM_X86_TRAP_PF_H
>  #define _ASM_X86_TRAP_PF_H
>  
> +#include <vdso/bits.h>  /* BIT() macro */

What are people's thoughts on using linux/bits.h instead of vdso.bits.h, even
though the vDSO version is technically sufficient?  Seeing the "vdso" reference
definitely made me blink slowly a few times.

> +
>  /*
>   * Page fault error code bits:
>   *
> @@ -12,15 +14,17 @@
>   *   bit 4 ==				1: fault was an instruction fetch
>   *   bit 5 ==				1: protection keys block access
>   *   bit 15 ==				1: SGX MMU page-fault
> + *   bit 31 ==				1: fault was an RMP violation
>   */
>  enum x86_pf_error_code {
> -	X86_PF_PROT	=		1 << 0,
> -	X86_PF_WRITE	=		1 << 1,
> -	X86_PF_USER	=		1 << 2,
> -	X86_PF_RSVD	=		1 << 3,
> -	X86_PF_INSTR	=		1 << 4,
> -	X86_PF_PK	=		1 << 5,
> -	X86_PF_SGX	=		1 << 15,
> +	X86_PF_PROT	=		BIT(0),
> +	X86_PF_WRITE	=		BIT(1),
> +	X86_PF_USER	=		BIT(2),
> +	X86_PF_RSVD	=		BIT(3),
> +	X86_PF_INSTR	=		BIT(4),
> +	X86_PF_PK	=		BIT(5),
> +	X86_PF_SGX	=		BIT(15),
> +	X86_PF_RMP	=		BIT(31),
>  };
>  
>  #endif /* _ASM_X86_TRAP_PF_H */
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 1c548ad00752..2715240c757e 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -545,6 +545,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long ad
>  		 !(error_code & X86_PF_PROT) ? "not-present page" :
>  		 (error_code & X86_PF_RSVD)  ? "reserved bit violation" :
>  		 (error_code & X86_PF_PK)    ? "protection keys violation" :
> +		 (error_code & X86_PF_RMP)   ? "rmp violation" :
>  					       "permissions violation");
>  
>  	if (!(error_code & X86_PF_USER) && user_mode(regs)) {
> -- 
> 2.17.1
>