Messages in this thread | | | Date | Mon, 8 May 2017 20:58:29 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v3 2/2] x86/refcount: Implement fast refcount overflow protection |
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On Mon, May 08, 2017 at 04:31:11PM -0700, Kees Cook wrote: > On Mon, May 8, 2017 at 3:53 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > On Mon, May 08, 2017 at 12:32:52PM -0700, Kees Cook wrote: > >> +#define REFCOUNT_EXCEPTION \ > >> + "movl $0x7fffffff, %[counter]\n\t" \ > >> + "int $"__stringify(X86_REFCOUNT_VECTOR)"\n" \ > >> + "0:\n\t" \ > >> + _ASM_EXTABLE(0b, 0b) > > > > Despite the objtool warnings going away, this still uses the exception > > table in a new way, which will confuse objtool. I need to do some more > > thinking about the best way to fix it, either as a change to your patch > > or a change to objtool. > > In that it's not a "true" exception?
Right. And also that it doesn't need the "fixup" since it would return to the same address anyway.
-- Josh
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