linux-kernel - Re: [PATCH 0/1] Add XSAVE layout description to Core files for debuggers to support varying XSAVE layouts

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Message-ID: <20240314163345.GBZfMm6Ve5QMY_xPjl@fat_crate.local>
Date: Thu, 14 Mar 2024 17:33:45 +0100
From: Borislav Petkov <bp@...en8.de>
To: "Willgerodt, Felix" <felix.willgerodt@...el.com>
Cc: Vignesh Balasubramanian <vigbalas@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-toolchains@...r.kernel.org" <linux-toolchains@...r.kernel.org>,
	"mpe@...erman.id.au" <mpe@...erman.id.au>,
	"npiggin@...il.com" <npiggin@...il.com>,
	"christophe.leroy@...roup.eu" <christophe.leroy@...roup.eu>,
	"aneesh.kumar@...nel.org" <aneesh.kumar@...nel.org>,
	"naveen.n.rao@...ux.ibm.com" <naveen.n.rao@...ux.ibm.com>,
	"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
	"keescook@...omium.org" <keescook@...omium.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"jinisusan.george@....com" <jinisusan.george@....com>,
	"matz@...e.de" <matz@...e.de>,
	"binutils@...rceware.org" <binutils@...rceware.org>,
	"jhb@...eBSD.org" <jhb@...ebsd.org>
Subject: Re: [PATCH 0/1] Add XSAVE layout description to Core files for
 debuggers to support varying XSAVE layouts

On Thu, Mar 14, 2024 at 04:25:44PM +0000, Willgerodt, Felix wrote:
> I am wondering if it wouldn't be easier for everyone if corefiles would just
> contain space for all possible XSAVE components?

You mean we should shuffle out from the kernel 8K of AMX state even if
nothing uses it or the machine doesn't even support it?

That's silly.

Please have a look at this:

+struct xfeat_component {
+       u32 xfeat_type;
+       u32 xfeat_sz;
+       u32 xfeat_off;
+       u32 xfeat_flags;
+} __packed;

What is wrong with having a blob of such xfeat_component things
describing the XSTATE buffer and parsing it in gdb?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette