>>> On 23.02.18 at 08:49, <mi...@kernel.org> wrote: > * Jan Beulich <jbeul...@suse.com> wrote: > >> >>> On 21.02.18 at 17:53, <mi...@kernel.org> wrote: >> >> > * Jan Beulich <jbeul...@suse.com> wrote: >> > >> >> Using just the leaf page table entry flags would cause a false warning >> >> in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry. >> >> Hand through both the current entry's flags as well as the accumulated >> >> effective value (the latter as pgprotval_t instead of pgprot_t, as it's >> >> not an actual entry's value). >> >> >> >> This in particular eliminates the false W+X warning when running under >> >> Xen, as commit 2cc42bac1c ("x86-64/Xen: eliminate W+X mappings") has to >> >> make the necessary adjustment in L2 rather than L1 (the reason is >> >> explained there). I.e. _PAGE_RW is clear there in L1, but _PAGE_NX is >> >> set in L2. >> >> >> >> Signed-off-by: Jan Beulich <jbeul...@suse.com> >> >> Reviewed-by: Juergen Gross <jgr...@suse.com> >> >> --- >> >> v2: Re-base onto tip tree. Add Xen related paragraph to description. >> >> --- >> >> arch/x86/mm/dump_pagetables.c | 92 >> > ++++++++++++++++++++++++++---------------- >> >> 1 file changed, 57 insertions(+), 35 deletions(-) >> > >> > There's a build failure with CONFIG_KASAN=y enabled: >> > >> > arch/x86/mm/dump_pagetables.c: In function ‘kasan_page_table’: >> > arch/x86/mm/dump_pagetables.c:365:3: error: too few arguments to function >> > ‘note_page’ >> > arch/x86/mm/dump_pagetables.c:238:13: note: declared here >> >> Oh, I see. Question though is what to pass as the extra argument: >> Do I need to pass in the caller's effective rights, or should I take >> kasan_page_table()'s checking against kasan_zero_p?d as an >> indication that the effective permission is zero here? I'm sorry for >> this probably trivial question, but I know nothing about how KASAN >> works. > > I'm not sure either - but I've Cc:-ed the KASAN gents who might be able to > help us out here?
Actually, the "zero" in the names of the symbols meanwhile makes me be pretty sure passing 0 for the effective permissions here is exactly what is wanted. I'm about to produce v3. Jan