From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>, X86 ML <x86@kernel.org>,
Borislav Petkov <bpetkov@suse.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Brian Gerst <brgerst@gmail.com>
Subject: Re: [RFC 6/7] x86/asm: Remap the TSS into the cpu entry area
Date: Mon, 13 Nov 2017 18:28:42 -0800 [thread overview]
Message-ID: <CA+55aFy1oxA-vMyvh7Z+vt3paj-XHkYbc8qU2vSFxOiATmrMjA@mail.gmail.com> (raw)
In-Reply-To: <CALCETrWDYxZPFT=N6N3Ukci_xEU3OHS+0tajihuf+03j=0paoQ@mail.gmail.com>
On Mon, Nov 13, 2017 at 6:25 PM, Andy Lutomirski <luto@kernel.org> wrote:
> On Mon, Nov 13, 2017 at 11:36 AM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> I forget what the actual size is, but aligning the hardware TSS struct
>> to 128 bytes might be sufficient. It's not that big.
>
> 104 bytes, so it's probably already fine. For anything except an
> actual task switch, only the first 12 or so bytes matter.
Note that historically, about half of the Intel errata (that don't get
fixed) are about TSS in oddball situations, mainly page crossers.
I may be exaggerating just a tiny bit, but it's definitely a "don't do it".
Linus
next prev parent reply other threads:[~2017-11-14 2:28 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-11 4:05 [RFC 0/7] Prep code for better stack switching Andy Lutomirski
2017-11-11 4:05 ` [RFC 1/7] x86/asm/64: Allocate and enable the SYSENTER stack Andy Lutomirski
2017-11-13 19:07 ` Dave Hansen
2017-11-14 2:17 ` Andy Lutomirski
2017-11-14 7:15 ` Ingo Molnar
2017-11-11 4:05 ` [RFC 2/7] x86/gdt: Put per-cpu GDT remaps in ascending order Andy Lutomirski
2017-11-11 4:05 ` [RFC 3/7] x86/fixmap: Generalize the GDT fixmap mechanism Andy Lutomirski
2017-11-11 4:05 ` [RFC 4/7] x86/asm: Fix assumptions that the HW TSS is at the beginning of cpu_tss Andy Lutomirski
2017-11-13 17:01 ` Dave Hansen
2017-11-26 13:48 ` [PATCH v2] x86/entry: " Ingo Molnar
2017-11-26 15:41 ` Andy Lutomirski
2017-11-26 15:58 ` Ingo Molnar
2017-11-26 16:00 ` Ingo Molnar
2017-11-26 16:05 ` Andy Lutomirski
2017-11-26 16:43 ` Ingo Molnar
2017-11-11 4:05 ` [RFC 5/7] x86/asm: Rearrange struct cpu_tss to enlarge SYSENTER_stack and fix alignment Andy Lutomirski
2017-11-11 4:11 ` Andy Lutomirski
2017-11-13 19:19 ` Dave Hansen
2017-11-11 4:05 ` [RFC 6/7] x86/asm: Remap the TSS into the cpu entry area Andy Lutomirski
2017-11-13 19:22 ` Dave Hansen
2017-11-13 19:36 ` Linus Torvalds
2017-11-14 2:25 ` Andy Lutomirski
2017-11-14 2:28 ` Linus Torvalds [this message]
2017-11-14 2:30 ` Andy Lutomirski
2017-11-14 2:27 ` Andy Lutomirski
2017-11-11 4:05 ` [RFC 7/7] x86/unwind/64: Add support for the SYSENTER stack Andy Lutomirski
2017-11-13 22:46 ` Josh Poimboeuf
2017-11-14 2:13 ` Andy Lutomirski
2017-11-11 10:58 ` [RFC 0/7] Prep code for better stack switching Borislav Petkov
2017-11-12 2:59 ` Andy Lutomirski
2017-11-12 4:25 ` Andy Lutomirski
2017-11-13 4:37 ` Andy Lutomirski
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