On 7/25/23 12:23 PM, Muhammad Usama Anjum wrote: > On 7/24/23 9:10 PM, Michał Mirosław wrote: > [...]>>>> @@ -2219,22 +2225,24 @@ static int pagemap_scan_get_args(struct > pm_scan_arg >>>>> *arg, >>>>> arg->category_anyof_mask | arg->return_mask) & ~PM_SCAN_CATEGORIES) >>>>> return -EINVAL; >>>>> >>>>> - start = untagged_addr((unsigned long)arg->start); >>>>> - end = untagged_addr((unsigned long)arg->end); >>>>> - vec = untagged_addr((unsigned long)arg->vec); >>>>> + arg->start = untagged_addr((unsigned long)arg->start); >>>>> + arg->end = untagged_addr((unsigned long)arg->end); >>>>> + arg->vec = untagged_addr((unsigned long)arg->vec); >>>> >>>> BTW, We should we keep the tag in args writeback(). >>> Sorry what? >>> After this function, the start, end and vec would be used. We need to make >>> sure that the address are untagged before that. >> >> We do write back the address the walk ended at to arg->start in >> userspace. This pointer I think needs the tag reconstructed so that >> retrying the ioctl() will be possible. > Even if we reconstruct the tag for end and vec, We need to update the start > address. Can we just put same tag as original start in it? I'm not sure. The special users would use tags. If they are using it, they'll just re-add the tag in next invocation. I think this implementation is correct. > -- BR, Muhammad Usama Anjum
