Commit dc068f46 authored by Greg Ungerer's avatar Greg Ungerer

m68knommu: set ZERO_PAGE() to the allocated zeroed page

The non-MMU m68k pagetable ZERO_PAGE() macro is being set to the
somewhat non-sensical value of "virt_to_page(0)". The zeroth page
is not in any way guaranteed to be a page full of "0". So the result
is that ZERO_PAGE() will almost certainly contain random values.

We already allocate a real "empty_zero_page" in the mm setup code shared
between MMU m68k and non-MMU m68k. It is just not hooked up to the
ZERO_PAGE() macro for the non-MMU m68k case.

Fix ZERO_PAGE() to use the allocated "empty_zero_page" pointer.

I am not aware of any specific issues caused by the old code.

Link: https://lore.kernel.org/linux-m68k/2a462b23-5b8e-bbf4-ec7d-778434a3b9d7@google.com/T/#tReported-by: default avatarHugh Dickens <hughd@google.com>
Signed-off-by: default avatarGreg Ungerer <gerg@linux-m68k.org>
parent 42226c98
......@@ -42,7 +42,8 @@ extern void paging_init(void);
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
#define ZERO_PAGE(vaddr) (virt_to_page(0))
extern void *empty_zero_page;
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
/*
* All 32bit addresses are effectively valid for vmalloc...
......
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