eh_frame confusion
From: Naveen N. Rao <hidden>
Date: 2020-03-05 12:47:33
Also in:
linux-kbuild, lkml
Naveen N. Rao wrote:
Naveen N. Rao wrote:quoted
Rasmus Villemoes wrote:
<snip>
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
# Never use string load/store instructions as they are # often slow when they are implemented at alldiff --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__ -sdiff --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