On Mon, Oct 15, 2018 at 07:34:14AM -0700, Andy Lutomirski wrote: > > > > On Oct 14, 2018, at 10:17 PM, Nathan Chancellor <natechancel...@gmail.com> > > wrote: > > > >> 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 > > > > > > Hmm, -dr wasn’t quite enough to dump the .discard bits, assuming they’re > there at all. Can you just put the whole .o file somewhere?
Here you go: https://nathanchance.me/downloads/.tmp/fault.o Thanks, Nathan
