From a9d099d17ef0af6deac4c3b4d15ad0555d258ec8 Mon Sep 17 00:00:00 2001
From: Jerome Forissier <jerome.forissier@linaro.org>
Date: Tue, 23 Aug 2022 11:41:00 +0000
Subject: [PATCH] core, ldelf: link: add -z execstack

When building for arm32 with GNU binutils 2.39, the linker outputs
warnings when generating some TEE core binaries (all_obj.o, init.o,
unpaged.o and tee.elf) as well as ldelf.elf:

 arm-poky-linux-gnueabi-ld.bfd: warning: atomic_a32.o: missing .note.GNU-stack section implies executable stack
 arm-poky-linux-gnueabi-ld.bfd: NOTE: This behaviour is deprecated and will be removed in a future version of the linker

The permissions used when mapping the TEE core stacks do not depend on
any metadata found in the ELF file. Similarly when the TEE core loads
ldelf it already creates a non-executable stack regardless of ELF
information. Therefore we can safely ignore the warnings. This is done
by adding the '-z execstack' option.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>

Signed-off-by: Anton Antonov <Anton.Antonov@arm.com>
Upstream-Status: Backport [https://github.com/OP-TEE/optee_os/pull/5499]

---
diff --git a/core/arch/arm/kernel/link.mk b/core/arch/arm/kernel/link.mk
index c39d43cb..0e96e606 100644
--- a/core/arch/arm/kernel/link.mk
+++ b/core/arch/arm/kernel/link.mk
@@ -9,6 +9,11 @@ link-script-dep = $(link-out-dir)/.kern.ld.d
 
 AWK	 = awk
 
+link-ldflags-common += $(call ld-option,--no-warn-rwx-segments)
+ifeq ($(CFG_ARM32_core),y)
+link-ldflags-common += $(call ld-option,--no-warn-execstack)
+endif
+
 link-ldflags  = $(LDFLAGS)
 ifeq ($(CFG_CORE_ASLR),y)
 link-ldflags += -pie -Bsymbolic -z norelro $(ldflag-apply-dynamic-relocs)
@@ -31,7 +36,7 @@ link-ldflags += -T $(link-script-pp) -Map=$(link-out-dir)/tee.map
 link-ldflags += --sort-section=alignment
 link-ldflags += --fatal-warnings
 link-ldflags += --gc-sections
-link-ldflags += $(call ld-option,--no-warn-rwx-segments)
+link-ldflags += $(link-ldflags-common)
 
 link-ldadd  = $(LDADD)
 link-ldadd += $(ldflags-external)
@@ -56,7 +61,7 @@ link-script-cppflags := \
 		$(cppflagscore))
 
 ldargs-all_objs := -T $(link-script-dummy) --no-check-sections \
-		   $(call ld-option,--no-warn-rwx-segments) \
+		   $(link-ldflags-common) \
 		   $(link-objs) $(link-ldadd) $(libgcccore)
 cleanfiles += $(link-out-dir)/all_objs.o
 $(link-out-dir)/all_objs.o: $(objs) $(libdeps) $(MAKEFILE_LIST)
@@ -70,7 +75,7 @@ $(link-out-dir)/unpaged_entries.txt: $(link-out-dir)/all_objs.o
 		$(AWK) '/ ____keep_pager/ { printf "-u%s ", $$3 }' > $@
 
 unpaged-ldargs := -T $(link-script-dummy) --no-check-sections --gc-sections \
-		 $(call ld-option,--no-warn-rwx-segments)
+		 $(link-ldflags-common)
 unpaged-ldadd := $(objs) $(link-ldadd) $(libgcccore)
 cleanfiles += $(link-out-dir)/unpaged.o
 $(link-out-dir)/unpaged.o: $(link-out-dir)/unpaged_entries.txt
@@ -99,7 +104,7 @@ $(link-out-dir)/init_entries.txt: $(link-out-dir)/all_objs.o
 		$(AWK) '/ ____keep_init/ { printf "-u%s ", $$3 }' > $@
 
 init-ldargs := -T $(link-script-dummy) --no-check-sections --gc-sections \
-	       $(call ld-option,--no-warn-rwx-segments)
+	       $(link-ldflags-common)
 init-ldadd := $(link-objs-init) $(link-out-dir)/version.o  $(link-ldadd) \
 	      $(libgcccore)
 cleanfiles += $(link-out-dir)/init.o
diff --git a/ldelf/link.mk b/ldelf/link.mk
index 64c8212a..bd49551e 100644
--- a/ldelf/link.mk
+++ b/ldelf/link.mk
@@ -20,6 +20,9 @@ link-ldflags += -z max-page-size=4096 # OP-TEE always uses 4K alignment
 ifeq ($(CFG_CORE_BTI),y)
 link-ldflags += $(call ld-option,-z force-bti) --fatal-warnings
 endif
+ifeq ($(CFG_ARM32_$(sm)), y)
+link-ldflags += $(call ld-option,--no-warn-execstack)
+endif
 link-ldflags += $(link-ldflags$(sm))
 
 link-ldadd  = $(addprefix -L,$(libdirs))