From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
the arch/x86 maintainers <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Andy Lutomirski <luto@amacapital.net>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC, PATCHv1 15/28] x86: detect 5-level paging support
Date: Tue, 13 Dec 2016 14:44:06 -0800 [thread overview]
Message-ID: <b393a48a-6e8b-6427-373c-2825641fea99@zytor.com> (raw)
In-Reply-To: <20161208202013.uutsny6avn5gimwq@pd.tnic>
On 12/08/16 12:20, Borislav Petkov wrote:
> On Thu, Dec 08, 2016 at 12:08:53PM -0800, Linus Torvalds wrote:
>> Especially since that's some of the ugliest inline asm ever due to the
>> nasty BX handling.
>
> Yeah, about that: why doesn't gcc handle that for us like it would
> handle a clobbered register? I mean, it *should* know that BX is live
> when building with -fPIC... The .ifnc thing looks really silly.
>
When compiling with -fPIC gcc treats ebx as a "fixed register". A fixed
register can't be spilled, and so a clobber of a fixed register is a
fatal error.
Like it or not, it's how it works.
-hpa
next prev parent reply other threads:[~2016-12-13 22:46 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 16:21 [RFC, PATCHv1 00/28] 5-level paging Kirill A. Shutemov
2016-12-08 16:21 ` [QEMU, PATCH] x86: implement la57 paging mode Kirill A. Shutemov
2016-12-08 16:48 ` [Qemu-devel] " no-reply
2016-12-08 16:21 ` [RFC, PATCHv1 01/28] asm-generic: introduce 5level-fixup.h Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 02/28] asm-generic: introduce __ARCH_USE_5LEVEL_HACK Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 03/28] arch, mm: convert all architectures to use 5level-fixup.h Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 04/28] asm-generic: introduce <asm-generic/pgtable-nop4d.h> Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 05/28] mm: convert generic code to 5-level paging Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 06/28] x86: basic changes into headers for " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 07/28] x86: trivial portion of 5-level paging conversion Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 08/28] x86/gup: add 5-level paging support Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 09/28] x86/ident_map: " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 10/28] x86/mm: add support of p4d_t in vmalloc_fault() Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 11/28] x86/power: support p4d_t in hibernate code Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 12/28] x86/kexec: support p4d_t Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 13/28] x86: convert the rest of the code to " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 14/28] mm: introduce __p4d_alloc() Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 15/28] x86: detect 5-level paging support Kirill A. Shutemov
2016-12-08 20:05 ` Borislav Petkov
2016-12-08 20:08 ` Linus Torvalds
2016-12-08 20:20 ` Borislav Petkov
2016-12-13 22:44 ` H. Peter Anvin [this message]
2016-12-13 23:07 ` Boris Petkov
2016-12-15 14:39 ` Borislav Petkov
2016-12-15 17:52 ` hpa
2016-12-15 19:09 ` Borislav Petkov
2016-12-15 19:20 ` Andi Kleen
2016-12-15 20:52 ` hpa
2016-12-15 20:57 ` hpa
2016-12-09 15:32 ` Kirill A. Shutemov
2016-12-09 16:33 ` Borislav Petkov
2016-12-13 22:50 ` H. Peter Anvin
2016-12-08 16:21 ` [RFC, PATCHv1 16/28] x86/asm: remove __VIRTUAL_MASK_SHIFT==47 assert Kirill A. Shutemov
2016-12-08 18:39 ` Andy Lutomirski
2016-12-08 19:22 ` Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for 5-level paging Kirill A. Shutemov
2016-12-08 18:56 ` Randy Dunlap
2016-12-08 19:24 ` Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 18/28] x86/paravirt: make paravirt code support " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 19/28] x86/mm: basic defines/helpers for CONFIG_X86_5LEVEL Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 20/28] x86/dump_pagetables: support 5-level paging Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 21/28] x86/mm: extend kasan to " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 22/28] x86/espfix: " Kirill A. Shutemov
2016-12-08 18:40 ` Andy Lutomirski
2016-12-12 14:22 ` Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 23/28] x86/mm: add support of additional page table level during early boot Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 24/28] x86/mm: add sync_global_pgds() for configuration with 5-level paging Kirill A. Shutemov
2016-12-08 18:42 ` Andy Lutomirski
2016-12-08 19:33 ` Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 25/28] x86/mm: make kernel_physical_mapping_init() support " Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 26/28] x86/mm: add support for 5-level paging for KASLR Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 27/28] x86: enable la57 support Kirill A. Shutemov
2016-12-08 16:21 ` [RFC, PATCHv1 28/28] TESTING-ONLY: bump TASK_SIZE_MAX Kirill A. Shutemov
2016-12-08 18:16 ` [RFC, PATCHv1 00/28] 5-level paging Linus Torvalds
2016-12-08 18:26 ` hpa
2016-12-08 19:20 ` Kirill A. Shutemov
2016-12-09 5:01 ` Ingo Molnar
2016-12-09 10:24 ` Arnd Bergmann
2016-12-09 10:51 ` Catalin Marinas
2016-12-09 10:37 ` Kirill A. Shutemov
2016-12-09 16:40 ` Andi Kleen
2016-12-09 17:21 ` Kirill A. Shutemov
2016-12-09 16:49 ` Dave Hansen
2016-12-13 21:06 ` Dave Hansen
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