On 02/04/2019 11:06, Catalin Marinas wrote:
> 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 ;).
>
No problem, my bad for not adding it in the first place ;).
--
Regards,
Vincenzo
