linux-kernel - Re: [PATCH v3 45/75] x86/dumpstack/64: Handle #VC exception stacks

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Date:   Fri, 22 May 2020 15:06:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 45/75] x86/dumpstack/64: Handle #VC exception stacks

On Tue, Apr 28, 2020 at 05:16:55PM +0200, Joerg Roedel wrote:
> diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
> index 14db05086bbf..2f3534ef4b5f 100644
> --- a/arch/x86/include/asm/stacktrace.h
> +++ b/arch/x86/include/asm/stacktrace.h
> @@ -21,6 +21,10 @@ enum stack_type {
>  	STACK_TYPE_ENTRY,
>  	STACK_TYPE_EXCEPTION,
>  	STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1,
> +#ifdef CONFIG_X86_64

CONFIG_AMD_MEM_ENCRYPT

> +	STACK_TYPE_VC,
> +	STACK_TYPE_VC_LAST = STACK_TYPE_VC + N_VC_STACKS - 1,
> +#endif
>  };
>  
>  struct stack_info {
> diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
> index 87b97897a881..2468963c1424 100644
> --- a/arch/x86/kernel/dumpstack_64.c
> +++ b/arch/x86/kernel/dumpstack_64.c
> @@ -18,6 +18,7 @@
>  
>  #include <asm/cpu_entry_area.h>
>  #include <asm/stacktrace.h>
> +#include <asm/sev-es.h>
>  
>  static const char * const exception_stack_names[] = {
>  		[ ESTACK_DF	]	= "#DF",
> @@ -47,6 +48,9 @@ const char *stack_type_name(enum stack_type type)
>  	if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
>  		return exception_stack_names[type - STACK_TYPE_EXCEPTION];
>  
> +	if (type >= STACK_TYPE_VC && type <= STACK_TYPE_VC_LAST)

That test can be inside vc_stack_name() so that it gets optimized away
for !CONFIG_AMD_MEM_ENCRYPT and there's no need for ifdeffery.

-- 
Regards/Gruss,
    Boris.

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