Re: [Xen-devel] [PATCH 6 of 8] Xen: remove run_in_exception_handler() and recode its only caller

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 15:38 +0000 on 07 Mar (1299512321), Tim Deegan wrote:
> At 15:15 +0000 on 07 Mar (1299510944), Keir Fraser wrote:
> > On 07/03/2011 15:05, "Keir Fraser" <keir.xen@xxxxxxxxx> wrote:
> > > On 07/03/2011 11:26, "Tim Deegan" <Tim.Deegan@xxxxxxxxxx> wrote:
> > >> This is needed to compile xen with clang, which can't handle using a
> > >> function name in an asm immediate.
> > > 
> > > Actually run_in_exception_handler() does have another user, in ns16550.c.
> > > Although non-essential, it makes the 'd' debug key much more useful when
> > > running the UART in polled mode.
> > > 
> > > So I suggest we keep run_in_exception_handler but modify it to pass the
> > > function pointer in (say) rAX.
> > 
> > Like the attached patch (against latest tip).
> 
> Sorry, I had missed that other user.  I'll see if I can find a way to
> make clang use the function address directly; if not, I'd be inclined to 
> have dump_execution_state have its own ID anyway, to keep %rax valid(er)
> in BUG()s.

Turns out to be very straightforward: another level of indirection makes
the parser happy.  If it's OK with you, I'll revert 22987:3147f2d1c6fb
and apply this instead:

diff -r 3147f2d1c6fb xen/include/asm-x86/bug.h
--- a/xen/include/asm-x86/bug.h Mon Mar 07 15:47:59 2011 +0000
+++ b/xen/include/asm-x86/bug.h Mon Mar 07 15:48:32 2011 +0000
@@ -22,7 +22,7 @@ struct bug_frame {
     asm volatile (                                 \
         "ud2 ; ret %0" BUG_STR(1)                  \
         : : "i" (BUGFRAME_run_fn),                 \
-            "i" (fn) )
+            "i" (&(fn)) )
 
 #define WARN()                                     \
     asm volatile (                                 \

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel