On Wed, Mar 01, 2017 at 12:15:38AM -0800, hpa@xxxxxxxxx wrote:
> On March 1, 2017 12:10:59 AM PST, tip-bot for Josh Poimboeuf <tipbot@xxxxxxxxx> wrote:
> >Commit-ID: 90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5
> >Gitweb:
> >http://git.kernel.org/tip/90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5
> >Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> >AuthorDate: Wed, 1 Mar 2017 00:05:04 -0600
> >Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> >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 <torvalds@xxxxxxxxxxxxxxxxxxxx>
> >Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> >Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> >Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> >Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> >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 <mingo@xxxxxxxxxx>
> >---
> > 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
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|