* Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> wrote: > On 05/10/2016 04:29 PM, Dmitry Safonov wrote: > >Add possibility for userspace 32-bit applications to move > >vdso mapping. Previously, when userspace app called > >mremap for vdso, in return path it would land on previous > >address of vdso page, resulting in segmentation violation. > >Now it lands fine and returns to userspace with remapped vdso. > >This will also fix context.vdso pointer for 64-bit, which does not > >affect the user of vdso after mremap by now, but this may change. > > > >As suggested by Andy, return EINVAL for mremap that splits vdso image. > > > >Renamed and moved text_mapping structure declaration inside > >map_vdso, as it used only there and now it complement > >vvar_mapping variable. > > > >There is still problem for remapping vdso in glibc applications: > >linker relocates addresses for syscalls on vdso page, so > >you need to relink with the new addresses. Or 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@xxxxxxxxxxxxx> > >Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> > >--- > >v8: add WARN_ON_ONCE on current->mm != new_vma->vm_mm > >v7: build fix > >v6: moved vdso_image_32 check and fixup code into vdso_fix_landing function > > with ifdefs around > >v5: as Andy suggested, add a check that new_vma->vm_mm and current->mm are > > the same, also check not only in_ia32_syscall() but image == &vdso_image_32 > >v4: drop __maybe_unused & use image from mm->context instead vdso_image_32 > >v3: as Andy suggested, return EINVAL in case of splitting vdso blob on mremap; > > used is_ia32_task instead of ifdefs > >v2: added __maybe_unused for pt_regs in vdso_mremap > > Ping? There's no 0/2 boilerplate explaining the background of the changes - why do you want to mremap() the vDSO? Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>