From: Andy Lutomirski <luto@amacapital.net>
To: Dmitry Safonov <dsafonov@virtuozzo.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
X86 ML <x86@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCHv2 4/5] x86/mm: for MAP_32BIT check in_compat_syscall() instead TIF_ADDR32
Date: Tue, 17 Jan 2017 12:30:47 -0800 [thread overview]
Message-ID: <CALCETrWXCr_nYMb41JSgVSAmMYkkkkDfWtLfQhh7S5Enz8YJCA@mail.gmail.com> (raw)
In-Reply-To: <20170116123310.22697-5-dsafonov@virtuozzo.com>
On Mon, Jan 16, 2017 at 4:33 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:
> At this momet, logic in arch_get_unmapped_area{,_topdown} for mmaps with
> MAP_32BIT flag checks TIF_ADDR32 which means:
> o if 32-bit ELF changes mode to 64-bit on x86_64 and then tries to
> mmap() with MAP_32BIT it'll result in addr over 4Gb (as default is
> top-down allocation)
> o if 64-bit ELF changes mode to 32-bit and tries mmap() with MAP_32BIT,
> it'll allocate only memory in 1GB space: [0x40000000, 0x80000000).
>
> Fix it by handeling MAP_32BIT in 64-bit syscalls only.
> As a little bonus it'll make thread flag a little less used.
Seems like an improvement. Also, jeez, the mmap code is complicated.
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next prev parent reply other threads:[~2017-01-17 20:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 12:33 [PATCHv2 0/5] Fix compatible mmap() return pointer over 4Gb Dmitry Safonov
2017-01-16 12:33 ` [PATCHv2 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions Dmitry Safonov
2017-01-16 12:33 ` [PATCHv2 2/5] x86/mm: introduce mmap_{,legacy}_base Dmitry Safonov
2017-01-16 14:28 ` kbuild test robot
2017-01-17 20:27 ` Andy Lutomirski
2017-01-18 11:26 ` Dmitry Safonov
2017-01-16 12:33 ` [PATCHv2 3/5] x86/mm: fix native mmap() in compat bins and vice-versa Dmitry Safonov
2017-01-16 13:31 ` kbuild test robot
2017-01-16 14:59 ` kbuild test robot
2017-01-17 20:29 ` Andy Lutomirski
2017-01-18 11:33 ` Dmitry Safonov
2017-01-16 12:33 ` [PATCHv2 4/5] x86/mm: for MAP_32BIT check in_compat_syscall() instead TIF_ADDR32 Dmitry Safonov
2017-01-17 20:30 ` Andy Lutomirski [this message]
2017-01-18 11:39 ` Dmitry Safonov
2017-01-16 12:33 ` [PATCHv2 5/5] selftests/x86: add test to check compat mmap() return addr Dmitry Safonov
2017-01-17 20:31 ` [PATCHv2 0/5] Fix compatible mmap() return pointer over 4Gb Andy Lutomirski
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