diff options
author | Roland Dreier <rdreier@cisco.com> | 2008-09-15 10:43:35 +0000 |
---|---|---|
committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2008-10-07 14:26:18 +1100 |
commit | a880e7623397bcb44877b012cd65baa11ad1bbf8 (patch) | |
tree | a413d15fbb5145feafed14bfa7e9ed433cf4603f /arch/powerpc/mm/mem.c | |
parent | 6ddc9d3200c25edddd7051f208dbbdd8e16f0734 (diff) |
powerpc: Avoid integer overflow in page_is_ram()
Commit 8b150478 ("ppc: make phys_mem_access_prot() work with pfns
instead of addresses") fixed page_is_ram() in arch/ppc to avoid overflow
for addresses above 4G on 32-bit kernels. However arch/powerpc's
page_is_ram() is missing the same fix -- it computes a physical address
by doing pfn << PAGE_SHIFT, which overflows if pfn corresponds to a page
above 4G.
In particular this causes pages above 4G to be mapped with the wrong
caching attribute; for example many ppc440-based SoCs have PCI space
above 4G, and mmap()ing MMIO space may end up with a mapping that has
caching enabled.
Fix this by working with the pfn and avoiding the conversion to
physical address that causes the overflow. This patch compares the
pfn to max_pfn, which is a semantic change from the old code -- that
code compared the physical address to high_memory, which corresponds
to max_low_pfn. However, I think that was is another bug, since
highmem pages are still RAM.
Reported-by: vb <vb@vsbe.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/mm/mem.c')
-rw-r--r-- | arch/powerpc/mm/mem.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 1c93c255873..98d7bf99533 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -75,11 +75,10 @@ static inline pte_t *virt_to_kpte(unsigned long vaddr) int page_is_ram(unsigned long pfn) { - unsigned long paddr = (pfn << PAGE_SHIFT); - #ifndef CONFIG_PPC64 /* XXX for now */ - return paddr < __pa(high_memory); + return pfn < max_pfn; #else + unsigned long paddr = (pfn << PAGE_SHIFT); int i; for (i=0; i < lmb.memory.cnt; i++) { unsigned long base; |