lkml.org 
[lkml]   [2004]   [Dec]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] PPC64 Make sure lppaca doesn't cross page boundary
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>

diff -urN linux-2.5/include/asm-ppc64/paca.h test/include/asm-ppc64/paca.h
--- linux-2.5/include/asm-ppc64/paca.h 2004-09-09 09:59:50.000000000 +1000
+++ test/include/asm-ppc64/paca.h 2004-12-13 13:56:00.350040112 +1100
@@ -99,11 +99,17 @@
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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 14:08    [W:0.020 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site