[PATCH v5 17/36] arm64/build: Remove .eh_frame* sections due to unwind tables

[Kees Cook]

Avoid .eh_frame* section generation by making sure both CFLAGS and AFLAGS
contain -fno-asychronous-unwind-tables and -fno-unwind-tables.

With all sources of .eh_frame now removed from the build, drop this
DISCARD so we can be alerted in the future if it returns unexpectedly
once orphan section warnings have been enabled.

Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 arch/arm64/Makefile             | 5 ++++-
 arch/arm64/kernel/vmlinux.lds.S | 1 -
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 70f5905954dd..35de43c29873 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -47,13 +47,16 @@ endif
 
 KBUILD_CFLAGS	+= -mgeneral-regs-only	\
 		   $(compat_vdso) $(cc_has_k_constraint)
-KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables
 KBUILD_CFLAGS	+= $(call cc-disable-warning, psabi)
 KBUILD_AFLAGS	+= $(compat_vdso)
 
 KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)
 KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
 
+# Avoid generating .eh_frame* sections.
+KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
+KBUILD_AFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
+
 ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
 prepare: stack_protector_prepare
 stack_protector_prepare: prepare0
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index df2916b25ee0..b29081d16a70 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -95,7 +95,6 @@ SECTIONS
 		*(.discard.*)
 		*(.interp .dynamic)
 		*(.dynsym .dynstr .hash .gnu.hash)
-		*(.eh_frame)
 	}
 
 	. = KIMAGE_VADDR + TEXT_OFFSET;
-- 
2.25.1