[tip:x86/urgent] x86: Fix jump label with RO/NX module protection crash

[tip-bot for matthieu castet]

Commit-ID:  8969691343354bdd80eff5405a0f879edbf013d6
Gitweb:     http://git.kernel.org/tip/8969691343354bdd80eff5405a0f879edbf013d6
Author:     matthieu castet <castet.matthieu@xxxxxxx>
AuthorDate: Sun, 23 Jan 2011 15:45:52 +0100
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sun, 23 Jan 2011 16:12:45 +0100

x86: Fix jump label with RO/NX module protection crash

If we use jump table in module init, there are marked
as removed in __jump_table section after init is done.

But we already applied ro permissions on the module, so
we can't modify a read only section (crash in
remove_jump_label_module_init).

Make the __jump_table section rw.

Signed-off-by: Matthieu CASTET <castet.matthieu@xxxxxxx>
Cc: Xiaotian Feng <xtfeng@xxxxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Siarhei Liakh <sliakh.lkml@xxxxxxxxx>
Cc: Xuxian Jiang <jiang@xxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Kees Cook <kees.cook@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
LKML-Reference: <4D3C3F20.7030203@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 arch/x86/include/asm/jump_label.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index f52d42e..574dbc2 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -14,7 +14,7 @@
 	do {							\
 		asm goto("1:"					\
 			JUMP_LABEL_INITIAL_NOP			\
-			".pushsection __jump_table,  \"a\" \n\t"\
+			".pushsection __jump_table,  \"aw\" \n\t"\
 			_ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
 			".popsection \n\t"			\
 			: :  "i" (key) :  : label);		\
--
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