eh_frame confusion

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Naveen N. Rao wrote:
Naveen N. Rao wrote:
Rasmus Villemoes wrote:
<snip>
Can you check if the below patch works? I am yet to test this in more detail, but would be good to know the implications for ppc32.

- Naveen


---
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index f35730548e42..5b5bf98b8217 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -239,10 +239,7 @@ KBUILD_CFLAGS += $(call cc-option,-mno-vsx)
 KBUILD_CFLAGS += $(call cc-option,-mno-spe)
 KBUILD_CFLAGS += $(call cc-option,-mspe=no)
-# 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)
+KBUILD_CFLAGS  += $(call cc-option,-fno-asynchronous-unwind-tables)

In terms of the CFI information, the primary difference I see with -fno-dwarf2-cfi-asm is that when dumping the debug frames, CIE indicates version 3, while otherwise (i.e., without -fno-dwarf2-cfi-asm and with/without -fasynchronous-unwind-tables), it is version 1, regardless of -gdwarf-2/-gdwarf-4. There are few more minor changes, but none of these looked significant to me.

# Never use string load/store instructions as they are
 # often slow when they are implemented at all
diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index e147bbdc12cd..d43b0b18137c 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -25,6 +25,7 @@ KCOV_INSTRUMENT := n
 UBSAN_SANITIZE := n
ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
+       -fasynchronous-unwind-tables \
        -Wl,-soname=linux-vdso32.so.1 -Wl,--hash-style=both
 asflags-y := -D__VDSO32__ -s
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
index 32ebb3522ea1..b2cbb5c49bad 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -13,6 +13,7 @@ KCOV_INSTRUMENT := n
 UBSAN_SANITIZE := n
ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
+       -fasynchronous-unwind-tables \
        -Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both
 asflags-y := -D__VDSO64__ -s

The above vdso hunks can be dropped since all our VDSO are assembly, so the above have no impact.


- Naveen




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