From 9fe901d124871f5781b9c4ccbb7ff93fdff9d39e Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Mon, 27 Mar 2006 15:20:00 -0800 Subject: [PATCH] [PATCH] powerpc: Workaround for pSeries RTAS bug A bug in the RTAS services incorrectly interprets some bits in the CR when called from the OS. Specifically, bits in CR4. The result could be a firmware crash that also takes down the partition. A firmware fix is in the works. We have seen this situation when performing DLPAR operations. As a temporary workaround, clear the CR in enter_rtas(). Note that enter_rtas() will not set any bits in CR4 before calling RTAS. Also note that the 32 bit version of enter_rtas() should have the same work around even though the chances of hitting the bug are much smaller due to the lack of DLPAR on 32 bit kernels. However, my assembly skills are a bit rusty and the 32 bit code doesn't seem to follow the conventions for where things should be saved. In addition, I don't have a system to test 32 bit kernels. Help creating and at least touch testing the same workaround for 32 bit would be appreciated. Signed-off-by: Mike Kravetz Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/entry_64.S | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 1060155..19ad5c6 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -617,6 +617,12 @@ _GLOBAL(enter_rtas) mfsrr1 r10 std r10,_SRR1(r1) + /* Temporary workaround to clear CR until RTAS can be modified to + * ignore all bits. + */ + li r0,0 + mtcr r0 + /* There is no way it is acceptable to get here with interrupts enabled, * check it with the asm equivalent of WARN_ON */ -- 2.7.4