On Wed, Mar 01, 2017 at 12:15:38AM -0800, h...@zytor.com wrote: > On March 1, 2017 12:10:59 AM PST, tip-bot for Josh Poimboeuf > <tip...@zytor.com> wrote: > >Commit-ID: 90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5 > >Gitweb: > >http://git.kernel.org/tip/90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5 > >Author: Josh Poimboeuf <jpoim...@redhat.com> > >AuthorDate: Wed, 1 Mar 2017 00:05:04 -0600 > >Committer: Ingo Molnar <mi...@kernel.org> > >CommitDate: Wed, 1 Mar 2017 07:38:25 +0100 > > > >objtool: Fix __unreachable section relocation size > > > >Linus reported the following commit broke module loading on his laptop: > > > >d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead > >ends") > > > >It showed errors like the following: > > > > module: overflow in relocation type 10 val ffffffffc02afc81 > > module: 'nvme' likely not compiled with -mcmodel=kernel > > > >The problem is that the __unreachable section addresses are stored > >using > >the '.long' asm directive, which isn't big enough for .text section > >relative kernel addresses. Use '.quad' instead. > > > >Suggested-by: Linus Torvalds <torva...@linux-foundation.org> > >Reported-by: Linus Torvalds <torva...@linux-foundation.org> > >Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> > >Cc: Peter Zijlstra <a.p.zijls...@chello.nl> > >Cc: Peter Zijlstra <pet...@infradead.org> > >Cc: Thomas Gleixner <t...@linutronix.de> > >Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other > >dead ends") > >Link: http://lkml.kernel.org/r/20170301060504.oltm3iws6fmubnom@treble > >Signed-off-by: Ingo Molnar <mi...@kernel.org> > >--- > > include/linux/compiler-gcc.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > >diff --git a/include/linux/compiler-gcc.h > >b/include/linux/compiler-gcc.h > >index 76e28c2..91a77a5 100644 > >--- a/include/linux/compiler-gcc.h > >+++ b/include/linux/compiler-gcc.h > >@@ -201,7 +201,7 @@ > > #define annotate_unreachable() ({ \ > > asm("%c0:\t\n" \ > > ".pushsection __unreachable, \"a\"\t\n" \ > >- ".long %c0b\t\n" \ > >+ ".quad %c0b\t\n" \ > > ".popsection\t\n" : : "i" (__LINE__)); \ > > }) > > #else > > Or perhaps better use relative addresses, so: > > .long foo - (.+4)
Hm, yeah, something like that would indeed be better as it only needs 4 bytes instead of 8. For this use case, the following seems to work: ".long %c0b - .\t\n" It produces the same relocation section+addend as before but with a X86_64_PC32 relocation. It looks like the above patch was already merged so I'll add that change to the TODO list unless Ingo can squash it with the above patch. -- Josh
