Messages in this thread | | | Date | Thu, 21 Mar 2019 19:27:45 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error_entry |
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On Thu, Mar 21, 2019 at 11:05:06AM -0700, Andy Lutomirski wrote:
> Ugh. > > I certainly agree in principle that sticking the CR2 read into the asm > is the right solution. But this patch makes the spaghetti even more > tangled. Maybe we can rearrange the code a bit so that the entry > sequence saves at least one register before calling error_entry, so we > can do it the obvious way.
What is the obvious way? Note that with all the Xen/paravirt-me-harder bits on, we need to clobber at least RAX to get CR2.
And most of the patch was munging the paravirt bits to make that happen.
Another thing I did notices is that CLAC and CLD are not next to one another in these paths.
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