From: Paul Mackerras <paulus@samba.org>
This patch is from Will Schmidt <willschm@us.ibm.com>, with some extra
comments from me.
On iSeries and on POWER5 machines, there is a data structure which is used
for communication between the hypervisor and the kernel, called the
`lppaca'. The kernel tells the hypervisor where it is, and the hypervisor
requires that it doesn't cross a page boundary. With other changes in the
last few months we have ended up with a situation where it could cross a
page boundary. This patch increases the alignment requirement for the
struct to make sure that it can't cross a page boundary.
This is a bug fix and should go into 2.6.10.
Signed-off-by: Will Schmidt <willschm@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/include/asm-ppc64/paca.h | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff -puN include/asm-ppc64/paca.h~ppc64-make-sure-lppaca-doesnt-cross-page-boundary include/asm-ppc64/paca.h
--- 25/include/asm-ppc64/paca.h~ppc64-make-sure-lppaca-doesnt-cross-page-boundary 2004-12-12 20:12:30.263328280 -0800
+++ 25-akpm/include/asm-ppc64/paca.h 2004-12-12 20:12:30.273326760 -0800
@@ -99,11 +99,17 @@ struct paca_struct {
u64 exdsi[8]; /* used for linear mapping hash table misses */
/*
- * iSeries structues which the hypervisor knows about - Not
- * sure if these particularly need to be cacheline aligned.
+ * iSeries structure which the hypervisor knows about -
+ * this structure should not cross a page boundary.
+ * The vpa_init/register_vpa call is now known to fail if the
+ * lppaca structure crosses a page boundary.
* The lppaca is also used on POWER5 pSeries boxes.
+ * The lppaca is 640 bytes long, and cannot readily change
+ * since the hypervisor knows its layout, so a 1kB
+ * alignment will suffice to ensure that it doesn't
+ * cross a page boundary.
*/
- struct ItLpPaca lppaca __attribute__((aligned(0x80)));
+ struct ItLpPaca lppaca __attribute__((__aligned__(0x400)));
#ifdef CONFIG_PPC_ISERIES
struct ItLpRegSave reg_save;
#endif
_