linux-kernel - [ 068/105] arch/tile: avoid generating .eh

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Date:	Sun, 28 Oct 2012 23:16:44 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Chris Metcalf <cmetcalf@...era.com>
Subject: [ 068/105] arch/tile: avoid generating .eh_frame information in modules

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Metcalf <cmetcalf@...era.com>

commit 627072b06c362bbe7dc256f618aaa63351f0cfe6 upstream.

The tile tool chain uses the .eh_frame information for backtracing.
The vmlinux build drops any .eh_frame sections at link time, but when
present in kernel modules, it causes a module load failure due to the
presence of unsupported pc-relative relocations.  When compiling to
use compiler feedback support, the compiler by default omits .eh_frame
information, so we don't see this problem.  But when not using feedback,
we need to explicitly suppress the .eh_frame.

Signed-off-by: Chris Metcalf <cmetcalf@...era.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/tile/Makefile |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/tile/Makefile b/arch/tile/Makefile
index 55640cf..3d15364 100644
--- a/arch/tile/Makefile
+++ b/arch/tile/Makefile
@@ -26,6 +26,10 @@ $(error Set TILERA_ROOT or CROSS_COMPILE when building $(ARCH) on $(HOST_ARCH))
   endif
 endif
 
+# The tile compiler may emit .eh_frame information for backtracing.
+# In kernel modules, this causes load failures due to unsupported relocations.
+KBUILD_CFLAGS   += -fno-asynchronous-unwind-tables
+
 ifneq ($(CONFIG_DEBUG_EXTRA_FLAGS),"")
 KBUILD_CFLAGS   += $(CONFIG_DEBUG_EXTRA_FLAGS)
 endif


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