Messages in this thread | | | Subject | Re: [PATCH] x86/mm: annotate no_context with UNWIND_HINTS | From | Andy Lutomirski <> | Date | Mon, 15 Oct 2018 07:34:14 -0700 |
| |
> On Oct 14, 2018, at 10:17 PM, Nathan Chancellor <natechancellor@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.desaulniers@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.desaulniers@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?
| |