Signed-off-by: Mark Cave-Ayland mark.cave-ayland@ilande.co.uk --- openbios-devel/arch/ppc/qemu/ofmem.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/openbios-devel/arch/ppc/qemu/ofmem.c b/openbios-devel/arch/ppc/qemu/ofmem.c index 0161a17..20e9a1a 100644 --- a/openbios-devel/arch/ppc/qemu/ofmem.c +++ b/openbios-devel/arch/ppc/qemu/ofmem.c @@ -549,9 +549,14 @@ ofmem_init(void) { ofmem_t *ofmem = ofmem_arch_get_private();
- ofmem_claim_phys(0, get_ram_bottom(), 0); - ofmem_claim_virt(0, get_ram_bottom(), 0); - ofmem_map(0, 0, get_ram_bottom(), 0); + /* Map the memory (don't map page 0 to allow catching of NULL dereferences) */ + ofmem_claim_phys(PAGE_SIZE, get_ram_bottom() - PAGE_SIZE, 0); + ofmem_claim_virt(PAGE_SIZE, get_ram_bottom() - PAGE_SIZE, 0); + ofmem_map(PAGE_SIZE, PAGE_SIZE, get_ram_bottom() - PAGE_SIZE, 0); + + /* Mark the first page as non-free */ + ofmem_claim_phys(0, PAGE_SIZE, 0); + ofmem_claim_virt(0, PAGE_SIZE, 0);
/* Map everything at the top of physical RAM 1:1, minus the OpenBIOS ROM in RAM copy */ ofmem_claim_phys(get_ram_top(), get_hash_base() + HASH_SIZE - get_ram_top(), 0);