> From: linux-hyperv-owner@xxxxxxxxxxxxxxx > <linux-hyperv-owner@xxxxxxxxxxxxxxx> On Behalf Of Dexuan Cui > Sent: Monday, June 15, 2020 10:42 AM > > > > > > Hi hch, > > > The patch is merged into the mainine recently, but unluckily we noticed > > > a warning with CONFIG_DEBUG_WX=y > > > > > > Should we revert this patch, or figure out a way to ask the DEBUG_WX > > > code to ignore this page? > > > > Are you sure it is hv_hypercall_pg? > Yes, 100% sure. I printed the value of hv_hypercall_pg and and it matched the > address in the warning line " x86/mm: Found insecure W+X mapping at > address". I did this experiment: 1. export vmalloc_exec and ptdump_walk_pgd_level_checkwx. 2. write a test module that calls them. 3. It turns out that every call of vmalloc_exec() triggers such a warning. vmalloc_exec() uses PAGE_KERNEL_EXEC, which is defined as (__PP|__RW| 0|___A| 0|___D| 0|___G) It looks the logic in note_page() is: for_each_RW_page, if the NX bit is unset, then report the page as an insecure W+X mapping. IMO this explains the warning? Thanks, -- Dexuan
