[tip:perf/kprobes] kprobes: Ensure blacklist data is aligned

tip-bot for Vineet Gupta
2014-05-07T19:21:25Z

Commit-ID: 69902c718c0b476e94ed7fccd3cf29ca39fe433a
Gitweb: http://git.kernel.org/tip/69902c718c0b476e94ed7fccd3cf29ca39fe433a
Author: Vineet Gupta <Vineet.Gupta1@synopsys.com>
AuthorDate: Thu, 1 May 2014 10:56:44 +0530
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 7 May 2014 21:04:57 +0200

kprobes: Ensure blacklist data is aligned

ARC Linux (not supporting native unaligned access) was failing
to boot because __start_kprobe_blacklist was not aligned.

This was because per generated vmlinux.lds it was emitted right
next to .rodata with strings etc hence could be randomly
unaligned.

Fix that by ensuring a word alignment. While 4 would suffice for
32bit arches and problem at hand, it is probably better to put 8.

| Path: (null) CPU: 0 PID: 1 Comm: swapper Not tainted
| 3.15.0-rc3-next-20140430 #2
| task: 8f044000 ti: 8f01e000 task.ti: 8f01e000
|
| [ECR ]: 0x00230400 => Misaligned r/w from 0x800fb0d3
| [EFA ]: 0x800fb0d3
| [BLINK ]: do_one_initcall+0x86/0x1bc
| [ERET ]: init_kprobes+0x52/0x120

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: <torvalds@linux-foundation.org>
Cc: <rusty@rustcorp.com.au>
Cc: <rdunlap@infradead.org>
Cc: <jeremy@goop.org>
Cc: <arnd@arndb.de>
Cc: <dl9pf@gmx.de>
Cc: <sparse@chrisli.org>
Cc: <anil.s.keshavamurthy@intel.com>
Cc: <davem@davemloft.net>
Cc: <ananth@in.ibm.com>
Cc: <masami.hiramatsu.pt@hitachi.com>
Cc: <chrisw@sous-sol.org>
Cc: <akataria@vmware.com>
Cc: anton Kolesov <Anton.Kolesov@synopsys.com>
Link: http://lkml.kernel.org/r/5361DB14.7010406@synopsys.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/asm-generic/vmlinux.lds.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 40ceb3c..8e0204a 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -110,7 +110,8 @@
#endif

#ifdef CONFIG_KPROBES
-#define KPROBE_BLACKLIST() VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
+#define KPROBE_BLACKLIST() . = ALIGN(8); \
+ VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
*(_kprobe_blacklist) \
VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
#else