On Sat, Jul 23, 2016 at 12:26:54AM +0200, Luis R. Rodriguez wrote: > On Fri, Jul 22, 2016 at 04:49:45PM -0500, Josh Poimboeuf wrote: > > On Fri, Jul 22, 2016 at 02:24:44PM -0700, Luis R. Rodriguez wrote: > > > diff --git a/tools/objtool/special.c b/tools/objtool/special.c > > > index bff8abb3a4aa..f0ad369f994b 100644 > > > --- a/tools/objtool/special.c > > > +++ b/tools/objtool/special.c > > > @@ -26,6 +26,10 @@ > > > #include "special.h" > > > #include "warn.h" > > > > > > +#include "../../include/asm-generic/sections.h" > > > +#include "../../include/asm-generic/tables.h" > > > +#include "../../include/linux/stringify.h" > > > + > > > #define EX_ENTRY_SIZE 12 > > > #define EX_ORIG_OFFSET 0 > > > #define EX_NEW_OFFSET 4 > > > @@ -63,7 +67,9 @@ struct special_entry entries[] = { > > > .feature = ALT_FEATURE_OFFSET, > > > }, > > > { > > > - .sec = "__jump_table", > > > + .sec = __stringify(SECTION_TBL(SECTION_DATA, > > > + __jump_table, > > > + SECTION_ORDER_ANY)), > > > .jump_or_nop = true, > > > .size = JUMP_ENTRY_SIZE, > > > .orig = JUMP_ORIG_OFFSET, > > > > (continuing our discussion from another thread...) > > > > I think tools code isn't allowed to include kernel files because the > > tools subdirectory is supposed to be completely independent. > > That was also the case for userpsace tools in scripts/ -- for instance > scripts/mod/modpost.c made an exception. What I've proposed here to > keep things simple was to ensure -UKERNEL is passed and then only > include files we know will work. > > Refer to the patch "kprobes: port .kprobes.text to section range" > in this series for an extension of the scripts/mod/modpost.c kernel > headers use. I think the rule of separating code is stricter for tools/ than it is for scripts/. The scripts are generally kernel-specific whereas the tools are independent. I believe the goal is to be able to copy them out of the kernel tree and still be able to compile them. > > As far as I can tell, the section name will always be > > ".data.tbl.__jump_table.any". Is that true? If so, any reason why we > > can't just hard-code the string here? > > Its a fair strategy, however if upstream changes the order name we'd > have to hand code this as well, by using a macro we keep it all in one > place. Hm, do you expect the section name to change often? > > As you saw, if the string > > changes, objtool will complain and 0-day will report it. > > Indeed, which is why I was hoping to instead stick to a standard > sections set of header files that lets us get these in on place. Actually, I meant that obtool reporting the change would be a good thing, in favor of just hard-coding the string. It lets objtool do its job of letting us know when something changes, like it did today. > The only place I hand coded in this series was in the perl > file scripts/recordmcount.pl but I suppose if we wanted to get > creative we could even generate a header for it too. > > If we want to avoid all this hacker include stuff another option > is to *generate* each respective sections.h for the kernel, and > also, one for tools, and one for perl. What do you think? If the generated files aren't checked into git, tools/ will rely on kernel files and will no longer be independent. If they *are* checked in, then we have to keep the files in sync. Either way it sounds like overkill, just to avoid hard-coding a string for which objtool will already warn if it changes. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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