On Tue, Apr 02, 2019 at 11:01:04AM +0100, Vincenzo Frascino wrote:
> On 01/04/2019 15:27, Catalin Marinas wrote:
> > On Mon, Apr 01, 2019 at 12:20:22PM +0100, Vincenzo Frascino wrote:
> >> +static int aarch32_sigreturn_setup(struct mm_struct *mm)
> >> +{
> >> + unsigned long addr;
> >> void *ret;
> >>
> >> - if (down_write_killable(&mm->mmap_sem))
> >> - return -EINTR;
> >> - current->mm->context.vdso = (void *)addr;
> >> + addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
> >> + if (IS_ERR_VALUE(addr)) {
> >> + ret = ERR_PTR(addr);
> >> + goto out;
> >> + }
> >>
> >> - /* Map vectors page at the high address. */
> >> ret = _install_special_mapping(mm, addr, PAGE_SIZE,
> >> - VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
> >> - &spec);
> >> + VM_READ | VM_EXEC | VM_MAYREAD |
> >> + VM_MAYWRITE | VM_MAYEXEC,
> >> + &aarch32_vdso_spec[1]);
> >
> > Any reason for setting VM_MAYWRITE here?
>
> VM_MAYWRITE is required to allow gdb to Copy-on-Write and set breakpoints.
Thanks. Please add a comment to the code so I don't ask again ;).
--
Catalin
