From: Dave Hansen <dave.hansen@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Vignesh Balasubramanian <vigbalas@amd.com>,
linux-kernel@vger.kernel.org, linux-toolchains@vger.kernel.org,
mpe@ellerman.id.au, npiggin@gmail.com,
christophe.leroy@csgroup.eu, aneesh.kumar@kernel.org,
naveen.n.rao@linux.ibm.com, ebiederm@xmission.com,
keescook@chromium.org, x86@kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org,
bpetkov@amd.com, jinisusan.george@amd.com, matz@suse.de,
binutils@sourceware.org, jhb@freebsd.org,
felix.willgerodt@intel.com
Subject: Re: [PATCH 1/1] x86/elf: Add a new .note section containing Xfeatures information to x86 core files
Date: Thu, 14 Mar 2024 09:19:15 -0700 [thread overview]
Message-ID: <6ce6aa20-25d2-4784-823f-2a18f592e002@intel.com> (raw)
In-Reply-To: <20240314160824.GDZfMg-J1VOyjxIMiV@fat_crate.local>
On 3/14/24 09:08, Borislav Petkov wrote:
> On Thu, Mar 14, 2024 at 08:37:09AM -0700, Dave Hansen wrote:
>> This is pretty close to just a raw dump of the XSAVE CPUID leaves.
>> Rather than come up with an XSAVE-specific ABI that depends on CPUID
>> *ANYWAY* (because it dumps the "flags" register aka. ECX), maybe we
>> should just bite the bullet and dump out (some of) the raw CPUID space.
>
> Funny you should say that. This was what they had done originally but if
> you dump CPUID and you want to add another component in the future which
> is *not* described by CPUID, your scheme breaks.
Are you envisioning an *XSAVE* state component that's not described by
CPUID?
Or some _other_ (non-XSAVE) component in a core dump that isn't
described by CPUID?
> So the idea is to have a self-describing buffers layout, independent
> from any x86-ism. You can extend this in a straight-forward way then
> later.
That argument breaks down a bit on the flags though:
xc.xfeat_flags = xstate_flags[i];
Because it comes _directly_ from CPUID with zero filtering:
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
...
xstate_flags[i] = ecx;
So this layout is quite dependent on what's in x86's CPUID.
next prev parent reply other threads:[~2024-03-14 16:19 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-14 11:23 [PATCH 0/1] Add XSAVE layout description to Core files for debuggers to support varying XSAVE layouts Vignesh Balasubramanian
2024-03-14 11:23 ` [PATCH 1/1] x86/elf: Add a new .note section containing Xfeatures information to x86 core files Vignesh Balasubramanian
2024-03-14 15:37 ` Dave Hansen
2024-03-14 16:08 ` Borislav Petkov
2024-03-14 16:19 ` Dave Hansen [this message]
2024-03-14 16:29 ` Borislav Petkov
2024-03-14 16:39 ` Dave Hansen
2024-03-26 9:59 ` Balasubrmanian, Vignesh
2024-03-15 23:51 ` Thomas Gleixner
2024-03-16 10:29 ` Borislav Petkov
2024-03-14 16:45 ` John Baldwin
2024-03-14 17:10 ` Dave Hansen
2024-03-14 17:36 ` John Baldwin
2024-03-14 17:05 ` John Baldwin
2024-03-14 16:13 ` Kees Cook
2024-03-26 10:06 ` Balasubrmanian, Vignesh
2024-03-14 22:13 ` Michael Ellerman
2024-03-26 10:09 ` Balasubrmanian, Vignesh
2024-03-15 9:59 ` kernel test robot
2024-03-15 12:59 ` kernel test robot
2024-03-14 16:25 ` [PATCH 0/1] Add XSAVE layout description to Core files for debuggers to support varying XSAVE layouts Willgerodt, Felix
2024-03-14 16:33 ` Borislav Petkov
2024-03-15 8:43 ` Willgerodt, Felix
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