From: Chris Friesen <cfriesen@nortel•com>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>
Subject: Re: somewhat OT -- trying to build code on the fly then run it
Date: Tue, 05 Apr 2005 11:03:44 -0600 [thread overview]
Message-ID: <4252C4F0.5000204@nortel.com> (raw)
In-Reply-To: <1112663005.26086.134.camel@gaston>
Benjamin Herrenschmidt wrote:
> bla can only be used for small addresses (or very high addresses), and
> it doesn't take a register argument but an absolute address. You want
> something different, more like
>
> mtctr %2
> bctrl
>
> Though you also need to add proper "clobber" constraints to indicate to
> the compiler what will be clobbered by the routine you are calling (look
> at the syscall macros of the kernel for an example of rather standard
> clobber lists).
Thanks for the tip. With those changes, the code runs perfectly. For
posterity, the new function looks like this:
int dotest(void *p)
{
int i=0;
asm volatile (" \n\
mr 3,%1 \n\
mtctr %2 \n\
bctrl \n\
mr %0,3 \n"
: "=r" (i)
: "r" (i), "r" (p)
: "ctr", "lr");
return i;
}
The bad news is that it seems to indicate that our kernel code to flush
the icache doesn't seem to work. I'll open a new thread for that.
Chris
next prev parent reply other threads:[~2005-04-05 17:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-04 23:32 somewhat OT -- trying to build code on the fly then run it Chris Friesen
2005-04-05 1:03 ` Benjamin Herrenschmidt
2005-04-05 17:03 ` Chris Friesen [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-04-05 15:08 Fillod Stephane
2005-04-05 16:43 ` Chris Friesen
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