Re: [PATCH] xen/x86: don't use '.ifnes' in bug frame construction.

[Keir Fraser <keir.xen@gmail.com>]

On 29/08/2013 16:55, "Tim Deegan" <tim@xen.org> 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. :|
> 
> Signed-off-by: Tim Deegan <tim@xen.org>

I'll leave it to Jan to Ack/apply this one.

 -- Keir

> ---
>  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[],