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| author |   Greg Ungerer <gerg@linux-m68k.org> | 2022-04-20 23:27:47 +1000 |
|---|---|---|
| committer | Greg Ungerer <gerg@linux-m68k.org> | 2022-05-16 13:18:30 +1000 |
| commit | dc068f46217970d9516f16cd37972a01d50dc055 (patch) | |
| tree | 90d1fce067e04440fd9eff6ea5ae83c18546524d /arch/m68k | |
| parent | Linux 5.18-rc7 (diff) | |
| download | linux-dev-dc068f46217970d9516f16cd37972a01d50dc055.tar.xz linux-dev-dc068f46217970d9516f16cd37972a01d50dc055.zip | |
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/#t
Reported-by: Hugh Dickens <hughd@google.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
| -rw-r--r-- | arch/m68k/include/asm/pgtable_no.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/m68k/include/asm/pgtable_no.h b/arch/m68k/include/asm/pgtable_no.h index 87151d67d91e..bce5ca56c388 100644 --- a/arch/m68k/include/asm/pgtable_no.h +++ b/arch/m68k/include/asm/pgtable_no.h @@ -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... |