On Sun, Oct 14, 2018 at 08:43:18PM -0700, Andy Lutomirski wrote: > 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
Hi Andy, Did you mean 'objdump -dr'? If so, here you go (rather long, sorry if I should have pasted it here instead): https://gist.github.com/nathanchance/f038bb0a6653b975bb8a4e64fcd5503e Nathan
