On Sat, Feb 18, 2023 at 01:14:12PM -0800, Rick Edgecombe wrote: > If a VMA has the VM_SHADOW_STACK flag, it is shadow stack memory. So > when it is made writable with pte_mkwrite(), it should create shadow > stack memory, not conventionally writable memory. Now that pte_mkwrite() > takes a VMA, and places where shadow stack memory might be created pass > one, pte_mkwrite() can know when it should do this. > > So make pte_mkwrite() create shadow stack memory when the VMA has the > VM_SHADOW_STACK flag. Do the same thing for pmd_mkwrite(). > > This requires referencing VM_SHADOW_STACK in these functions, which are > currently defined in pgtable.h, however mm.h (where VM_SHADOW_STACK is > located) can't be pulled in without causing problems for files that > reference pgtable.h. So also move pte/pmd_mkwrite() into pgtable.c, where > they can safely reference VM_SHADOW_STACK. > > Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx> > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> Is there any realistic performance impact from making these not inline now? Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
