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. > 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? > diff --git a/include/asm-generic/vmlinux.lds.h > b/include/asm-generic/vmlinux.lds.h > index 3558f4eb1a86..2f2f34942689 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -446,9 +446,18 @@ > ALIGN_FUNCTION(); \ > *(.text.hot .text .text.fixup .text.unlikely) \ > *(.ref.text) \ > + REFCOUNT_TEXT \ > MEM_KEEP(init.text) \ > MEM_KEEP(exit.text) \ > > +#define __REFCOUNT_TEXT(section) \ > + VMLINUX_SYMBOL(__##section##_start) = .; \ > + *(.text.##section) \ > + VMLINUX_SYMBOL(__##section##_end) = .; > + > +#define REFCOUNT_TEXT > \ > + __REFCOUNT_TEXT(refcount_overflow) \ > + __REFCOUNT_TEXT(refcount_underflow) Same here. -- Josh
