From 325cdacd03c12629aa5f9ee2ace49b1f3dc184a8 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Sat, 15 Jul 2017 00:10:58 -0500 Subject: debug: Fix WARN_ON_ONCE() for modules Mike Galbraith reported a situation where a WARN_ON_ONCE() call in DRM code turned into an oops. As it turns out, WARN_ON_ONCE() seems to be completely broken when called from a module. The bug was introduced with the following commit: 19d436268dde ("debug: Add _ONCE() logic to report_bug()") That commit changed WARN_ON_ONCE() to move its 'once' logic into the bug trap handler. It requires a writable bug table so that the BUGFLAG_DONE bit can be written to the flags to indicate the first warning has occurred. The bug table was made writable for vmlinux, which relies on vmlinux.lds.S and vmlinux.lds.h for laying out the sections. However, it wasn't made writable for modules, which rely on the ELF section header flags. Reported-by: Mike Galbraith Tested-by: Masami Hiramatsu Signed-off-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 19d436268dde ("debug: Add _ONCE() logic to report_bug()") Link: http://lkml.kernel.org/r/a53b04235a65478dd9afc51f5b329fdc65c84364.1500095401.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/s390/include/asm/bug.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h index 1bbd9dbfe4e0..ce9cc123988b 100644 --- a/arch/s390/include/asm/bug.h +++ b/arch/s390/include/asm/bug.h @@ -14,7 +14,7 @@ ".section .rodata.str,\"aMS\",@progbits,1\n" \ "2: .asciz \""__FILE__"\"\n" \ ".previous\n" \ - ".section __bug_table,\"a\"\n" \ + ".section __bug_table,\"aw\"\n" \ "3: .long 1b-3b,2b-3b\n" \ " .short %0,%1\n" \ " .org 3b+%2\n" \ @@ -30,7 +30,7 @@ asm volatile( \ "0: j 0b+2\n" \ "1:\n" \ - ".section __bug_table,\"a\"\n" \ + ".section __bug_table,\"aw\"\n" \ "2: .long 1b-2b\n" \ " .short %0\n" \ " .org 2b+%1\n" \ -- cgit v1.2.3