Re: [PATCH v5 1/8] common: assembly entry point type/size annotations

[Jan Beulich <jbeulich@suse.com>]

On 17.01.2024 18:02, Roger Pau Monné wrote:
> On Mon, Jan 15, 2024 at 03:34:05PM +0100, Jan Beulich wrote:
>> Recent gas versions generate minimalistic Dwarf debug info for items
>> annotated as functions and having their sizes specified [1]. Furthermore
>> generating live patches wants items properly annotated. "Borrow" Arm's
>> END() and (remotely) derive other annotation infrastructure from
>> Linux'es, for all architectures to use.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> 
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks.

>> --- /dev/null
>> +++ b/xen/include/xen/linkage.h
>> @@ -0,0 +1,54 @@
>> +#ifndef __LINKAGE_H__
>> +#define __LINKAGE_H__
>> +
>> +#ifdef __ASSEMBLY__
>> +
>> +#include <xen/macros.h>
>> +
>> +/* CODE_ALIGN needs to be specified by every architecture. */
>> +#ifndef CODE_FILL
>> +# define CODE_FILL ~0
>> +#endif
>> +
>> +#ifndef DATA_ALIGN
>> +# define DATA_ALIGN 0
>> +#endif
>> +#ifndef DATA_FILL
>> +# define DATA_FILL ~0
> 
> I find the fills a bit odd, compared to what we use now (nops for x86
> IIRC).

Well, these are generic defaults. X86 then overrides CODE_FILL for it
to remain NOP. ~0 is the best I can think of as an arch-agnostic default,
considering the half dozen architectures I know at least a little.

Jan