From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] xen/x86: don't use '.ifnes' in bug frame construction. Date: Fri, 30 Aug 2013 09:35:00 +0100 Message-ID: <52205934.5080200@citrix.com> References: <1377791751-31533-1-git-send-email-tim@xen.org> <522073FD02000078000EFA2D@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VFKAb-0008UD-EP for xen-devel@lists.xenproject.org; Fri, 30 Aug 2013 08:35:05 +0000 In-Reply-To: <522073FD02000078000EFA2D@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel , keir@xen.org, Tim Deegan List-Id: xen-devel@lists.xenproject.org On 30/08/13 09:29, Jan Beulich wrote: >>>> On 29.08.13 at 17:55, Tim Deegan wrote: >> Spotted because it breaks the clang build for LLVM <3.2. .ifnes is >> not right here as it will choke on a string with embedded quotes. >> >> .ifnb would be better except that LLVM <3.2 doesn't support that either. >> It should be possible to use something like !!msg or !!msg[0] instead >> of a separate flag, but I gave up trying to find something that would >> make it through CPP, asm() and gas as a usable constant. :| > I'm not really opposed to this (albeit I dislike redundancy like this), > but I'd really like to understand (also for the sake of my own > education, including to avoid introducing similar breakage in the > future) where the problem was, and how gcc+gas manage to > accept what you appear to have found broken in general (i.e. not > just for clang as I understand it). > > And yes, I would have preferred (and used) .ifnb if I hadn't recalled > it having been me adding the support for it for binutils 2.17, while at > least one of the so far lowest common denominator distros (SLE10) > is only at 2.16. (which appears to have the needed > support, but it would seem wrong to draw the line at some > intermediary release); not sure what binutils version RHEL5 uses. > > Jan My CentOS 5.7 environment claims binutils 2.17.50 ~Andrew > >> Signed-off-by: Tim Deegan >> --- >> xen/include/asm-x86/bug.h | 14 ++++++++------ >> 1 file changed, 8 insertions(+), 6 deletions(-) >> >> diff --git a/xen/include/asm-x86/bug.h b/xen/include/asm-x86/bug.h >> index 148975f..e5dd559 100644 >> --- a/xen/include/asm-x86/bug.h >> +++ b/xen/include/asm-x86/bug.h >> @@ -25,7 +25,7 @@ struct bug_frame { >> #define BUGFRAME_bug 2 >> #define BUGFRAME_assert 3 >> >> -#define BUG_FRAME(type, line, ptr, msg) do { >> \ >> +#define BUG_FRAME(type, line, ptr, second_frame, msg) do { >> \ >> BUILD_BUG_ON((line) >> (BUG_LINE_LO_WIDTH + BUG_LINE_HI_WIDTH)); >> \ >> asm volatile ( ".Lbug%=: ud2\n" >> \ >> ".pushsection .bug_frames.%c0, \"a\", @progbits\n" >> \ >> @@ -33,7 +33,7 @@ struct bug_frame { >> ".Lfrm%=:\n" >> \ >> ".long (.Lbug%= - .Lfrm%=) + %c4\n" >> \ >> ".long (%c1 - .Lfrm%=) + %c3\n" >> \ >> - ".ifnes \"" msg "\", \"\"\n" >> \ >> + ".if " #second_frame "\n" >> \ >> ".long 0, %c2 - .Lfrm%=\n" >> \ >> ".endif\n" >> \ >> ".popsection" >> \ >> @@ -44,12 +44,14 @@ struct bug_frame { >> "i" (((line) >> BUG_LINE_LO_WIDTH) << BUG_DISP_WIDTH)); \ >> } while (0) >> >> -#define WARN() BUG_FRAME(BUGFRAME_warn, __LINE__, __FILE__, "") >> -#define BUG() BUG_FRAME(BUGFRAME_bug, __LINE__, __FILE__, "") >> >> -#define run_in_exception_handler(fn) BUG_FRAME(BUGFRAME_run_fn, 0, fn, "") >> +#define WARN() BUG_FRAME(BUGFRAME_warn, __LINE__, __FILE__, 0, NULL) >> +#define BUG() BUG_FRAME(BUGFRAME_bug, __LINE__, __FILE__, 0, NULL) >> >> -#define assert_failed(msg) BUG_FRAME(BUGFRAME_assert, __LINE__, __FILE__, >> msg) >> +#define run_in_exception_handler(fn) BUG_FRAME(BUGFRAME_run_fn, 0, fn, 0, >> NULL) >> + >> +#define assert_failed(msg) \ >> + BUG_FRAME(BUGFRAME_assert, __LINE__, __FILE__, 1, msg) >> >> extern const struct bug_frame __start_bug_frames[], >> __stop_bug_frames_0[], >> -- >> 1.7.10.4 > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel