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From: Andy Lutomirski <luto@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <h.peter.anvin@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Bae, Chang Seok" <chang.seok.bae@intel.com>,
	"Metzger, Markus T" <markus.t.metzger@intel.com>
Subject: Re: [PATCH v3 7/7] x86/ldt,ptrace: provide regset access to the LDT
Date: Fri, 22 Jun 2018 08:30:43 -0700	[thread overview]
Message-ID: <CALCETrUdNZ9xUBi7116uU5dvufH9TcBTzcq5MvLoG7M7rcqLOg@mail.gmail.com> (raw)
In-Reply-To: <8991CF11-DDE0-4E93-B913-82968DCFB661@zytor.com>

On Fri, Jun 22, 2018 at 8:06 AM <hpa@zytor.com> wrote:
>
> On June 22, 2018 7:49:13 AM PDT, Andy Lutomirski <luto@kernel.org> wrote:
> >On Thu, Jun 21, 2018 at 2:18 PM H. Peter Anvin, Intel
> ><h.peter.anvin@intel.com> wrote:
> >>
> >> From: "H. Peter Anvin" <hpa@linux.intel.com>
> >>
> >> Provide ptrace/regset access to the LDT, if one exists.  This
> >> interface provides both read and write access. The write code is
> >> unified with modify_ldt(); the read code doesn't have enough
> >> similarity so it has been kept made separate.
> >
> >For this and for the GDT, you've chosen to use struct user_desc as
> >your format instead of using a native hardware descriptor format.  Any
> >particular reason why?  If nothing else, it will bloat core files a
> >bit more than needed.
>
> I did because REGSET_TLS was implemented that way, and that is simply a subset of the GDT (which made the same code trivially applicable to both.) modify_ldt() does it *both* ways for extra fun (one for reading, and one for writing.)
>
> ->active is defined as "beyond this point the regset contains only the default value", which seemed appropriate in this case.

I saw that definition too.  But I'm still very unclear as to what, if
anything, the code actually does :)

--Andy

  reply	other threads:[~2018-06-22 15:31 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-21 21:17 [PATCH v3 0/7] x86/ptrace: regset access to the GDT and LDT H. Peter Anvin, Intel
2018-06-21 21:17 ` [PATCH v3 1/7] x86/ldt: refresh %fs and %gs in refresh_ldt_segments() H. Peter Anvin, Intel
2018-06-22 14:24   ` Andy Lutomirski
2018-06-22 18:29     ` H. Peter Anvin
2018-06-22 18:47       ` Andy Lutomirski
2018-06-27 18:19         ` Andy Lutomirski
2018-06-27 18:22           ` hpa
2018-06-27 18:33             ` hpa
2018-06-28 20:33             ` Andy Lutomirski
2018-06-28 20:39               ` hpa
2018-06-21 21:17 ` [PATCH v3 2/7] x86/ldt: use a common value for read_default_ldt() H. Peter Anvin, Intel
2018-06-21 21:17 ` [PATCH v3 3/7] x86: move fill_user_desc() from tls.c to desc.h and add validity check H. Peter Anvin, Intel
2018-06-21 21:17 ` [PATCH v3 4/7] x86/tls: create an explicit config symbol for the TLS area in the GDT H. Peter Anvin, Intel
2018-06-21 21:17 ` [PATCH v3 5/7] x86/segment: add #define for the last user-visible GDT slot H. Peter Anvin, Intel
2018-06-21 21:17 ` [PATCH v3 6/7] x86/tls,ptrace: provide regset access to the GDT H. Peter Anvin, Intel
2018-06-22 14:43   ` Andy Lutomirski
2018-06-21 21:17 ` [PATCH v3 7/7] x86/ldt,ptrace: provide regset access to the LDT H. Peter Anvin, Intel
2018-06-22 14:49   ` Andy Lutomirski
2018-06-22 15:05     ` hpa
2018-06-22 15:30       ` Andy Lutomirski [this message]
2018-06-22  1:58 ` [PATCH v3 0/7] x86/ptrace: regset access to the GDT and LDT Ingo Molnar
2018-06-22  2:25   ` hpa

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