On Sun, Oct 14, 2018 at 5:37 PM Nick Desaulniers <nick.desaulni...@gmail.com> wrote: > > Fixes the objtool warning: > arch/x86/mm/fault.o: warning: objtool: no_context()+0x220: unreachable > instruction > > Link: https://github.com/ClangBuiltLinux/linux/issues/204 > Signed-off-by: Nick Desaulniers <nick.desaulni...@gmail.com> > --- > arch/x86/mm/fault.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > index 47bebfe6efa7..057d2178fa19 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -760,9 +760,11 @@ no_context(struct pt_regs *regs, unsigned long > error_code, > * and then double-fault, though, because we're likely to > * break the console driver and lose most of the stack dump. > */ > - asm volatile ("movq %[stack], %%rsp\n\t" > + asm volatile (UNWIND_HINT_SAVE > + "movq %[stack], %%rsp\n\t" > "call handle_stack_overflow\n\t" > - "1: jmp 1b" > + "1: jmp 1b\n\t" > + UNWIND_HINT_RESTORE > : ASM_CALL_CONSTRAINT > : "D" ("kernel stack overflow (page fault)"), > "S" (regs), "d" (address),
NAK. Just below this snippet is unreachable(); Can you reply with objtool -dr output on a problematic fault.o? Josh, it *looks* like annotate_unreachable() should be doing the right thing, but something is clearly busted. Also, shouldn't compiler-clang.h contain a reasonable definition of unreachable()? --Andy
