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Date: Wed, 30 Apr 2008 07:28:13 +1000
From: Paul Mackerras <paulus@samba.org>
To: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [PATCH] [POWERPC] convert transfer_to_handler into a macro
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Kumar Gala writes:

> We need to have unique transfer_to_handler paths for each exception level
> that is supported.  We need to use the proper xSRR0/1 depending on which
> exception level the interrupt was from.  The macro conversion lets up
> templatize this code path.

It seems to me that this implies you are assuming that you will never
ever get a synchronous normal interrupt such as a TLB miss while you
are in a critical or machine check handler.

Wouldn't it be better and safer to have the exception prolog for
critical interrupts save SRR0/1 in the stack frame, and have the
prolog for machine checks save SRR0/1 and CSRR0/1 likewise?

Paul.