From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Ingo Molnar <mingo@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Borislav Petkov <bp@suse.de>, Andi Kleen <ak@linux.intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv4 3/4] x86/boot/compressed/64: Introduce place_trampoline()
Date: Fri, 8 Dec 2017 14:07:22 +0300 [thread overview]
Message-ID: <20171208110722.gl2cxdq2vlg6olih@node.shutemov.name> (raw)
In-Reply-To: <20171207063048.w46rrq2euzhtym3j@gmail.com>
On Thu, Dec 07, 2017 at 07:30:48AM +0100, Ingo Molnar wrote:
> > We also need a small stack in the trampoline to re-enable long mode via
> > long return. But stack and code can share the page just fine.
>
> BTW., I'm not sure this is necessarily a good idea: it means writable+executable
> memory, which we generally try to avoid. How complicated would it be to have them
> separate?
It's trivial: you only need to bump TRAMPOLINE_32BIT_SIZE.
But it doesn't make much sense. We're running from indentity mapping: all
memory is r/w without NX bit set (and IA32_EFER.NXE is 0).
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2017-12-08 11:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-05 13:59 [PATCHv4 0/4] x86: 5-level related changes into decompression code Kirill A. Shutemov
2017-12-05 13:59 ` [PATCHv4 1/4] x86/boot/compressed/64: Fix build with GCC < 5 Kirill A. Shutemov
2017-12-07 6:16 ` Ingo Molnar
2017-12-05 13:59 ` [PATCHv4 2/4] x86/boot/compressed/64: Rename pagetable.c to kaslr_64.c Kirill A. Shutemov
2017-12-07 6:17 ` Ingo Molnar
2017-12-05 13:59 ` [PATCHv4 3/4] x86/boot/compressed/64: Introduce place_trampoline() Kirill A. Shutemov
2017-12-07 6:30 ` Ingo Molnar
2017-12-07 8:17 ` Matthew Wilcox
2017-12-07 8:24 ` Ingo Molnar
2017-12-08 11:07 ` Kirill A. Shutemov [this message]
2017-12-08 11:28 ` Ingo Molnar
2017-12-05 13:59 ` [PATCHv4 4/4] x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G Kirill A. Shutemov
2017-12-07 7:03 ` Ingo Molnar
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