On Mon, May 8, 2017 at 3:53 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> 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? >> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h >> index 532372c6cf15..0590f384f234 100644 >> --- a/include/asm-generic/sections.h >> +++ b/include/asm-generic/sections.h >> @@ -20,6 +20,8 @@ >> * may be out of this range on some architectures. >> * [_sinittext, _einittext]: contains .init.text.* sections >> * [__bss_start, __bss_stop]: contains BSS sections >> + * [__refcount_overflow/underflow_start, ..._end]: contains .text sections >> + * for refcount error handling. >> * >> * Following global variables are optional and may be unavailable on some >> * architectures and/or kernel configurations. >> @@ -39,6 +41,8 @@ extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[]; >> extern char __kprobes_text_start[], __kprobes_text_end[]; >> extern char __entry_text_start[], __entry_text_end[]; >> extern char __start_rodata[], __end_rodata[]; >> +extern char __refcount_overflow_start[], __refcount_overflow_end[]; >> +extern char __refcount_underflow_start[], __refcount_underflow_end[]; > > I think this part is no longer needed, since you got rid of the new > sections? Oh whoops, thanks. I thought I'd removed those, but clearly I didn't. :) Thanks! -Kees -- Kees Cook Pixel Security
