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| author | Dmitry Safonov <dsafonov@virtuozzo.com> | 2016-06-28 14:35:38 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-07-08 15:17:51 +0300 |
| commit | b059a453b1cf1c8453c2b2ed373d3147d6264ebd (patch) | |
| tree | d06330fe10b872e9df51589e986ac43aabf8d762 /include/linux | |
| parent | 39380b80d72723282f0ea1d1bbf2294eae45013e (diff) | |
| download | linux-b059a453b1cf1c8453c2b2ed373d3147d6264ebd.tar.xz | |
x86/vdso: Add mremap hook to vm_special_mapping
Add possibility for 32-bit user-space applications to move
the vDSO mapping.
Previously, when a user-space app called mremap() for the vDSO
address, in the syscall return path it would land on the previous
address of the vDSOpage, resulting in segmentation violation.
Now it lands fine and returns to userspace with a remapped vDSO.
This will also fix the context.vdso pointer for 64-bit, which does
not affect the user of vDSO after mremap() currently, but this
may change in the future.
As suggested by Andy, return -EINVAL for mremap() that would
split the vDSO image: that operation cannot possibly result in
a working system so reject it.
Renamed and moved the text_mapping structure declaration inside
map_vdso(), as it used only there and now it complements the
vvar_mapping variable.
There is still a problem for remapping the vDSO in glibc
applications: the linker relocates addresses for syscalls
on the vDSO page, so you need to relink with the new
addresses.
Without that the next syscall through glibc may fail:
Program received signal SIGSEGV, Segmentation fault.
#0 0xf7fd9b80 in __kernel_vsyscall ()
#1 0xf7ec8238 in _exit () from /usr/lib32/libc.so.6
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: 0x7f454c46@gmail.com
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160628113539.13606-2-dsafonov@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mm_types.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index ca3e517980a0..917f2b6a0cde 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -594,6 +594,9 @@ struct vm_special_mapping { int (*fault)(const struct vm_special_mapping *sm, struct vm_area_struct *vma, struct vm_fault *vmf); + + int (*mremap)(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma); }; enum tlb_flush_reason { |