The patch titled
x86: ioremap ram check fix
has been added to the -mm tree. Its filename is
x86-ioremap-ram-check-fix.patch
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Subject: x86: ioremap ram check fix
From: Andres Salomon <dilinger@xxxxxxxxxx>
bdd3cee2e4b7279457139058615ced6c2b41e7de (x86: ioremap(), extend check
to all RAM pages) breaks OLPC's ioremap call. The ioremap that OLPC uses is:
romsig = ioremap(0xffffffc0, 16);
The commit that breaks it is basically:
- for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
- (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+ for (pfn = phys_addr >> PAGE_SHIFT;
+ (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+
Previously, the 'pfn < max_pfn_mapped' check would've caused us to not
enter the loop. Removing that check means we loop infinitely. The
reason for that is because pfn is 0xfffff, and last_addr is 0xffffffcf.
The remaining check that is used to exit the loop is not sufficient;
when pfn<<PAGE_SHIFT is 0xfffff000, that is less than 0xffffffcf; when
we increment pfn and it overflows (pfn == 0x100000), pfn<<PAGE_SHIFT
ends up being 0. That, of course, is less than last_addr. In effect,
pfn<<PAGE_SHIFT is never lower than last_addr.
The simple fix for this is to limit the last_addr check to the PAGE_MASK;
a patch is below.
Signed-off-by: Andres Salomon <dilinger@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/ioremap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN arch/x86/mm/ioremap.c~x86-ioremap-ram-check-fix arch/x86/mm/ioremap.c
--- a/arch/x86/mm/ioremap.c~x86-ioremap-ram-check-fix
+++ a/arch/x86/mm/ioremap.c
@@ -149,7 +149,8 @@ static void __iomem *__ioremap_caller(re
* Don't allow anybody to remap normal RAM that we're using..
*/
for (pfn = phys_addr >> PAGE_SHIFT;
- (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+ (pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK);
+ pfn++) {
int is_ram = page_is_ram(pfn);
_
Patches currently in -mm which might be from dilinger@xxxxxxxxxx are
origin.patch
x86-ioremap-ram-check-fix.patch
x86-geode-cache-results-from-geode_has_vsa2-and-uninline.patch
x86-geode-cache-results-from-geode_has_vsa2-and-uninline-cleanup.patch
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