So far (xlate|unxlate)_dev_mem_ptr for read/write /dev/mem relies on a generic
high_memory check in valid_phys_addr_range(), which does not allow to access any
memory above high_memory whatsoever. By adding the high_memory check to
(xlate|unxlate)_dev_mem_ptr, it still will be possible to use __va safely for
kernel mapped memory and it will also allow read/write to access non-system RAM
above high_memory once the high_memory check is removed from
valid_phys_addr_range.
Signed-off-by: Frantisek Hrbata <fhrbata@xxxxxxxxxx>
---
arch/x86/mm/ioremap.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index baff1da..1ae7323 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -320,8 +320,11 @@ void *xlate_dev_mem_ptr(unsigned long phys)
void *addr;
unsigned long start = phys & PAGE_MASK;
- /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */
- if (page_is_ram(start >> PAGE_SHIFT))
+ /*
+ * If page is RAM and is mapped by kernel, we can use __va.
+ * Otherwise ioremap and unmap.
+ */
+ if (page_is_ram(start >> PAGE_SHIFT) && phys <= __pa(high_memory))
return __va(phys);
addr = (void __force *)ioremap_cache(start, PAGE_SIZE);
@@ -333,7 +336,7 @@ void *xlate_dev_mem_ptr(unsigned long phys)
void unxlate_dev_mem_ptr(unsigned long phys, void *addr)
{
- if (page_is_ram(phys >> PAGE_SHIFT))
+ if (page_is_ram(phys >> PAGE_SHIFT) && phys <= __pa(high_memory))
return;
iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK));
--
1.9.3
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