On Sat, Jul 18, 2015 at 09:16:58AM -0700, Linus Torvalds wrote: > On Jul 17, 2015 09:57, "Josh Poimboeuf" <jpoimboe@xxxxxxxxxx> wrote: > > > > + > > +#define STACKVALIDATE_IGNORE_INSN \ > > + ".Ltemp" __stringify(__LINE__) ":;" \ > > This is wrong. It won't work for people who do multiple of these on the > same line (think macros etc). > > For temporary labels, you should just use numeric labels. Think Pascal > style ones. Then use "b" or "f" after the number when referring to it to > say "back" or "forward" reference. > > So the code for an endless loop with a true temporary label looks like: > > 1: code > jmp 1b > > and a branch over would look like > > jne 7f > .. code ... > 7: ... > > and now you can have multiple of these truly temp labels without ever > getting errors from having a label redefined. Yeah, I think I'll change the C macro to do that. However for asm macros you have to worry about collisions. For example: .macro FOO 1: ... .endm 1: ... FOO jmp 1b It would jump to "1" in the macro instead of the "1" before the macro. So for the asm version of the macro I ended up using Andy's idea of using "\@" to get a unique identifier: .macro STACKVALIDATE_IGNORE_INSN .if CONFIG_STACK_VALIDATION .Ltemp_\@: .pushsection __stackvalidate_ignore_insn, "a" _ASM_ALIGN .long .Ltemp_\@ - . .popsection .endif .endm -- Josh -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
