arm64/build: Remove .eh_frame* sections due to unwind tables

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@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200821194310.3089815-11-keescook@chromium.org

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 55bc854..6de7f55 100644 (file)
--- 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 13fc2ec..c2b8426 100644 (file)
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -94,7 +94,6 @@ SECTIONS
                *(.discard.*)
                *(.interp .dynamic)
                *(.dynsym .dynstr .hash .gnu.hash)
-               *(.eh_frame)
        }
 
        . = KIMAGE_VADDR + TEXT_OFFSET;