From: Andi Kleen <a...@firstfloor.org>
Better dwarf2 unwind information is a good thing, it allows better
debugging with kgdb and crash and helps systemtap.
Commit 003086497f07f7f1e67c0c295e261740f822b377 ("Build with
-fno-dwarf2-cfi-asm") disabled some CFI information globally to work
around a module loader bug on powerpc.
But this disables the better unwind tables for all architectures, not just
powerpc. Move the workaround to powerpc and also add a suitable comment
that's it really a workaround.
This improves dwarf2 unwind tables on x86 at least.
Signed-off-by: Andi Kleen <a...@linux.intel.com>
Cc: Kyle McMartin <k...@mcmartin.ca>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Michal Marek <mma...@suse.cz>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
Makefile | 3 ---
arch/powerpc/Makefile | 5 +++++
2 files changed, 5 insertions(+), 3 deletions(-)
diff -puN Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only Makefile
--- a/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
+++ a/Makefile
@@ -579,9 +579,6 @@ KBUILD_CFLAGS += $(call cc-option,-Wno-p
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
-# revert to pre-gcc-4.4 behaviour of .eh_frame
-KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
-
# conserve stack if available
KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)
diff -puN arch/powerpc/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
arch/powerpc/Makefile
--- a/arch/powerpc/Makefile~kbuild-move-fno-dwarf2-cfi-asm-to-powerpc-only
+++ a/arch/powerpc/Makefile
@@ -112,6 +112,11 @@ KBUILD_CFLAGS += $(call cc-option,-mspe=
# kernel considerably.
KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
+# FIXME: the module load should be taught about the additional relocs
+# generated by this.
+# revert to pre-gcc-4.4 behaviour of .eh_frame
+KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)
+
# Never use string load/store instructions as they are
# often slow when they are implemented at all
KBUILD_CFLAGS += -mno-string
_
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