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Groups > linux.kernel > #1585065
| From | Michael Pratt <mpratt@google.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR |
| Date | 2017-02-21 07:20 +0100 |
| Message-ID | <tdbXQ-78b-21@gated-at.bofh.it> (permalink) |
| References | (2 earlier) <tbX0T-q0-47@gated-at.bofh.it> <tbXkd-wK-7@gated-at.bofh.it> <tbXWV-11n-13@gated-at.bofh.it> <tbZP3-2hr-13@gated-at.bofh.it> <tdbXQ-78b-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Sigh... apologies for the HTML. Trying again...
On Mon, Feb 20, 2017 at 9:21 PM, Michael Pratt <linux@pratt.im> wrote:
> On Fri, Feb 17, 2017 at 3:02 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>> On Fri, Feb 17, 2017 at 1:01 PM, Linus Torvalds
>> <torvalds@linux-foundation.org> wrote:
>>> On Fri, Feb 17, 2017 at 12:12 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>>>
>>>> At the very least, I'd want to see
>>>> MAP_FIXED_BUT_DONT_BLOODY_UNMAP_ANYTHING. I *hate* the current
>>>> interface.
>>>
>>> That's unrelated, but I guess w could add a MAP_NOUNMAP flag, and then
>>> you can use MAP_FIXED | MAP_NOUNMAP or something.
>>>
>>> But that has nothing to do with the 47-vs-56 bit issue.
>>>
>>>> How about MAP_LIMIT where the address passed in is interpreted as an
>>>> upper bound instead of a fixed address?
>>>
>>> Again, that's a unrelated semantic issue. Right now - if you don't
>>> pass in MAP_FIXED at all, the "addr" argument is used as a starting
>>> value for deciding where to find an unmapped area. But there is no way
>>> to specify the end. That would basically be what the process control
>>> thing would be (not per-system-call, but per-thread ).
>>>
>>
>> What I'm trying to say is: if we're going to do the route of 48-bit
>> limit unless a specific mmap call requests otherwise, can we at least
>> have an interface that doesn't suck?
I've got a set of patches that I've meant to send out as an RFC for a
while that tries to address userspace control of address space layout
and covers many of these ideas.
There is a new syscall and set of prctls for controlling the "mmap
layout" (i.e., get_unmapped_area search range) that look something
like this:
struct mmap_layout {
unsigned long start;
unsigned long end;
/*
* These are equivalent to mmap_legacy_base and mmap_base,
* but are not really needed in this proposal.
*/
unsigned long low_base;
unsigned long high_base;
unsigned long flags;
};
/* For flags */
#define MMAP_TOPDOWN 1
struct layout_mmap_args {
unsigned long addr;
unsigned long len;
unsigned long prot;
unsigned long flags;
unsigned long fd;
unsigned long off;
struct mmap_layout layout;
};
void *layout_mmap(struct layout_mmap_args *args);
int prctl(PR_GET_MMAP_LAYOUT, struct mmap_layout *layout);
int prctl(PR_SET_MMAP_LAYOUT, struct mmap_layout *layout);
The prctls control the default range that mmap and friends will
allocate. For 56-bit user address space, it could default to
[mmap_min_addr, 1<<47), as Linus suggests. Applications that want the
full address space can increase it to cover the entire range.
The layout_mmap syscall allows one-off mappings that fall outside the
default layout, and nicely solves the "MAP_FIXED but don't unmap
anything problem" by passing an explicit range to check without
actually setting MAP_FIXED.
This idea is quite similar to the MAX_VADDR + default
get_unmapped_area behavior ides, just more generalized to give
userspace more control over the ultimate behavior of
get_unmapped_area.
PS. Apologies if my email client screwed up this message. I didn't
have this thread in my client and have tried to import it from another
account.
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[PATCHv3 00/33] 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 30/33] x86/mm: make kernel_physical_mapping_init() support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 14/33] x86/kexec: support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 25/33] x86/dump_pagetables: support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 12/33] x86/mm: add support of p4d_t in vmalloc_fault() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 10/33] x86/gup: add 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 27/33] x86/espfix: support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 05/33] asm-generic: introduce <asm-generic/pgtable-nop4d.h> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 15/33] x86/efi: handle p4d in EFI pagetables "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
Re: [PATCHv3 15/33] x86/efi: handle p4d in EFI pagetables Matt Fleming <matt@codeblueprint.co.uk> - 2017-02-28 13:40 +0100
[PATCHv3 32/33] x86: enable 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 26/33] x86/kasan: extend to support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
[PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:20 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:00 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Dmitry Safonov <0x7f454c46@gmail.com> - 2017-02-21 13:00 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-21 13:50 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-17 18:30 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 18:30 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 21:10 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-17 21:30 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 22:10 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Andy Lutomirski <luto@amacapital.net> - 2017-02-18 00:10 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR hpa@zytor.com - 2017-02-18 00:20 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Michael Pratt <mpratt@google.com> - 2017-02-21 07:20 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Catalin Marinas <catalin.marinas@arm.com> - 2017-02-21 11:40 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-21 11:50 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Catalin Marinas <catalin.marinas@arm.com> - 2017-02-21 12:00 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-17 22:10 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Linus Torvalds <torvalds@linux-foundation.org> - 2017-02-17 22:20 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR hpa@zytor.com - 2017-02-17 23:00 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-18 10:30 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-20 14:20 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR Dave Hansen <dave.hansen@intel.com> - 2017-02-21 21:50 +0100
Re: [PATCHv3 33/33] mm, x86: introduce PR_SET_MAX_VADDR and PR_GET_MAX_VADDR "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-02-22 14:10 +0100
[PATCHv3 23/33] x86/paravirt: make paravirt code support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 13/33] x86/power: support p4d_t in hibernate code "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 28/33] x86/mm: add support of additional page table level during early boot "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 21/33] x86/asm: remove __VIRTUAL_MASK_SHIFT==47 assert "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 04/33] arch, mm: convert all architectures to use 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 01/33] x86/cpufeature: Add 5-level paging detection "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 08/33] x86: basic changes into headers for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 03/33] asm-generic: introduce __ARCH_USE_5LEVEL_HACK "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 07/33] mm: introduce __p4d_alloc() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 16/33] x86/mm/pat: handle additional page table "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 19/33] x86: convert the rest of the code to support p4d_t "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 11/33] x86/ident_map: add 5-level paging support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
[PATCHv3 18/33] x86/xen: convert __xen_pgd_walk() and xen_cleanmfnmap() to support p4d "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-02-17 15:30 +0100
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