From: Jan Kiszka <[email protected]> Page protection changes issued via mprotect, e.g. to enable executable stacks, cause spurious minor faults as they remove the write permission from the modified range again. Avoid this by faking shared pages so that vm_get_page_prot returns the desired page permissions.
Signed-off-by: Jan Kiszka <[email protected]> --- mm/mprotect.c | 12 +++++++++++- 1 files changed, 11 insertions(+), 1 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 5a688a2..3f234b3 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -147,6 +147,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, { struct mm_struct *mm = vma->vm_mm; unsigned long oldflags = vma->vm_flags; + unsigned long protflags; long nrpages = (end - start) >> PAGE_SHIFT; unsigned long charged = 0; pgoff_t pgoff; @@ -205,8 +206,17 @@ success: * held in write mode. */ vma->vm_flags = newflags; + protflags = newflags; +#ifdef CONFIG_IPIPE + /* + * Enforce non-COW vm_page_prot by faking VM_SHARED on locked regions. + */ + if (test_bit(MMF_VM_PINNED, &mm->flags) && + ((vma->vm_flags | mm->def_flags) & VM_LOCKED)) + protflags |= VM_SHARED; +#endif vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, - vm_get_page_prot(newflags)); + vm_get_page_prot(protflags)); if (vma_wants_writenotify(vma)) { vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); -- 1.7.1 _______________________________________________ Adeos-main mailing list [email protected] https://mail.gna.org/listinfo/adeos-main
