On systems where there is MMIO space between different blocks of RAM in
the physical address space, __ioremap_caller did not allow mapping these
MMIO areas, because they were below the end RAM and thus considered RAM
as well. Use the memblock-based page_is_ram function, which returns
false for such MMIO holes.
v2:
Keep the check for p < virt_to_phys(high_memory). On 32-bit systems
with high memory (memory above physical address 4GiB), the high memory
is expected to be available though ioremap. The high_memory variable
marks the end of low memory; comparing against it means that only
ioremap requests for low RAM will be denied.
Reported by Michael Ellerman.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
* mem_init() sets high_memory so only do the check after that.
*/
if (slab_is_available() && (p < virt_to_phys(high_memory)) &&
+ page_is_ram(__phys_to_pfn(p)) &&
!(__allow_ioremap_reserved && memblock_is_region_reserved(p, size))) {
printk("__ioremap(): phys addr 0x%llx is RAM lr %ps\n",
(unsigned long long)p, __builtin_return_address(0));