Messages in this thread | | | Date | Wed, 2 Jan 2002 13:42:21 -0700 | From | Tom Rini <> | Subject | Re: [PATCH] C undefined behavior fix |
| |
On Wed, Jan 02, 2002 at 12:13:34PM -0800, Joe Buck wrote: > > > Okay, here's a summary of all of the options we have: > > 1) Change this particular strcpy to a memcpy > > 2) Add -ffreestanding to the CFLAGS of arch/ppc/kernel/prom.o (If this > > optimization comes back on with this flag later on, it would be a > > compiler bug, yes?) > > 3) Modify the RELOC() marco in such a way that GCC won't attempt to > > optimize anything which touches it [1]. (Franz, again by Jakub) > > 4) Introduce a function to do the calculations [2]. (Corey Minyard) > > 5) 'Properly' set things up so that we don't need the RELOC() macros > > (-mrelocatable or so?), and forget this mess altogether. > > 2) will prevent any future gcc from ever assuming it can transform the > strcpy into anything but a call to strcpy, or assume anything about the > semantics of strcpy.
If we go with this, it also might make sense to split all of the {PTR,UN,}RELOC() macro users into a different file or split up btext.c a bit more, just to be safe.
> Be careful with 3), as trying to fool the optimizer > is likely to be only a temporary solution (meaning that the kernel people > will return to flame the gcc people when the optimizer gets changed > again).
Well, it's one of those changes that really should stop gcc, unless there's a bug on the gcc side, if I read the patch/comments about it right.
-- Tom Rini (TR1265) http://gate.crashing.org/~trini/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |