| Message ID | 3336bb02792d56c49d18e2f7a435fd194a4a22e4.1466192946.git.luto@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jun 17, 2016 at 01:00:39PM -0700, Andy Lutomirski wrote: > It's currently only used in the EFI code, which is safe AFAICT. "It is basically useful for a pagetable hierarchy which is not init_mm." > Warn if anyone tries to use it on the normal kernel pgd. > > Signed-off-by: Andy Lutomirski <luto@kernel.org> > --- > arch/x86/mm/pageattr.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 6a8026918bf6..e9b9c5cedbb8 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -1996,6 +1996,9 @@ out: > void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address, > unsigned numpages) > { > + /* Unmapping kernel entries from init_mm's pgd is not allowed. */ > + WARN_ON(root == init_mm.pgd); We can also return and not do the unmapping: if (WARN_ON(root == init_mm.pgd)) return;
On Fri, Jun 17, 2016 at 1:30 PM, Borislav Petkov <bp@alien8.de> wrote: > On Fri, Jun 17, 2016 at 01:00:39PM -0700, Andy Lutomirski wrote: >> It's currently only used in the EFI code, which is safe AFAICT. > > "It is basically useful for a pagetable hierarchy which is not init_mm." > >> Warn if anyone tries to use it on the normal kernel pgd. >> >> Signed-off-by: Andy Lutomirski <luto@kernel.org> >> --- >> arch/x86/mm/pageattr.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c >> index 6a8026918bf6..e9b9c5cedbb8 100644 >> --- a/arch/x86/mm/pageattr.c >> +++ b/arch/x86/mm/pageattr.c >> @@ -1996,6 +1996,9 @@ out: >> void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address, >> unsigned numpages) >> { >> + /* Unmapping kernel entries from init_mm's pgd is not allowed. */ >> + WARN_ON(root == init_mm.pgd); > > We can also return and not do the unmapping: > > if (WARN_ON(root == init_mm.pgd)) > return; I'll do one better: the only function that calls this function is unused. I'll just delete it. --Andy
On Sat, Jun 18, 2016 at 03:29:01AM -0700, Andy Lutomirski wrote: > I'll do one better: the only function that calls this function is > unused. I'll just delete it. Fair enough - Matt is on CC. Btw, normally I'm almost never talking to you at that time of the day, what's up? Can't sleep? :-))
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 6a8026918bf6..e9b9c5cedbb8 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -1996,6 +1996,9 @@ out: void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address, unsigned numpages) { + /* Unmapping kernel entries from init_mm's pgd is not allowed. */ + WARN_ON(root == init_mm.pgd); + unmap_pgd_range(root, address, address + (numpages << PAGE_SHIFT)); }
It's currently only used in the EFI code, which is safe AFAICT. Warn if anyone tries to use it on the normal kernel pgd. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/mm/pageattr.c | 3 +++ 1 file changed, 3 insertions(+)