Messages in this thread Patch in this message | | | Date | Mon, 13 Dec 2004 14:04:34 +1100 | From | Paul Mackerras <> | Subject | [PATCH] PPC64 Make sure lppaca doesn't cross page boundary |
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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/
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