[Buildroot] [PATCH 1/1] linux: disable SSP on s390 when needed

[Fabrice Fontaine]

Fix build failure raised since commit
810ba387bec3c5b6904e8893fb4cb6f9d3717466 by disabling SSP when needed

Fixes:
 - https://gitlab.com/kubu93/buildroot/-/jobs/1247043361

Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
---
 ...02-arch-s390-disable-SSP-when-needed.patch | 47 +++++++++++++++++++
 linux/linux.mk                                |  7 +++
 2 files changed, 54 insertions(+)
 create mode 100644 linux/0002-arch-s390-disable-SSP-when-needed.patch

diff --git a/linux/0002-arch-s390-disable-SSP-when-needed.patch b/linux/0002-arch-s390-disable-SSP-when-needed.patch
new file mode 100644
index 0000000000..c8199d4fd6
--- /dev/null
+++ b/linux/0002-arch-s390-disable-SSP-when-needed.patch
@@ -0,0 +1,47 @@
+From 8a054081678ed0b0e56f829bac0a4656e3a198b9 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice at gmail.com>
+Date: Sat, 8 May 2021 22:03:11 +0200
+Subject: [PATCH] arch/s390: disable SSP when needed
+
+Though -nostdlib is passed in PURGATORY_LDFLAGS and -ffreestanding in
+KBUILD_CFLAGS_DECOMPRESSOR, -fno-stack-protector must also be passed to
+avoid linking errors related to undefined references to
+'__stack_chk_guard' and '__stack_chk_fail' if toolchain enforces
+-fstack-protector.
+
+Fixes:
+ - https://gitlab.com/kubu93/buildroot/-/jobs/1247043361
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
+---
+ arch/s390/Makefile           | 1 +
+ arch/s390/purgatory/Makefile | 1 +
+ 2 files changed, 2 insertions(+)
+
+diff --git a/arch/s390/Makefile b/arch/s390/Makefile
+index e443ed9947bd..098abe3a56f3 100644
+--- a/arch/s390/Makefile
++++ b/arch/s390/Makefile
+@@ -28,6 +28,7 @@ KBUILD_CFLAGS_DECOMPRESSOR += -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY
+ KBUILD_CFLAGS_DECOMPRESSOR += -fno-delete-null-pointer-checks -msoft-float -mbackchain
+ KBUILD_CFLAGS_DECOMPRESSOR += -fno-asynchronous-unwind-tables
+ KBUILD_CFLAGS_DECOMPRESSOR += -ffreestanding
++KBUILD_CFLAGS_DECOMPRESSOR += -fno-stack-protector
+ KBUILD_CFLAGS_DECOMPRESSOR += $(call cc-disable-warning, address-of-packed-member)
+ KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
+ KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
+diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile
+index c57f8c40e992..21c4ebe29b9a 100644
+--- a/arch/s390/purgatory/Makefile
++++ b/arch/s390/purgatory/Makefile
+@@ -24,6 +24,7 @@ KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes
+ KBUILD_CFLAGS += -Wno-pointer-sign -Wno-sign-compare
+ KBUILD_CFLAGS += -fno-zero-initialized-in-bss -fno-builtin -ffreestanding
+ KBUILD_CFLAGS += -c -MD -Os -m64 -msoft-float -fno-common
++KBUILD_CFLAGS += -fno-stack-protector
+ KBUILD_CFLAGS += $(CLANG_FLAGS)
+ KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
+ KBUILD_AFLAGS := $(filter-out -DCC_USING_EXPOLINE,$(KBUILD_AFLAGS))
+-- 
+2.30.2
+
diff --git a/linux/linux.mk b/linux/linux.mk
index 1457228eb9..338e79d23d 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -274,6 +274,13 @@ define LINUX_TRY_PATCH_TIMECONST
 endef
 LINUX_POST_PATCH_HOOKS += LINUX_TRY_PATCH_TIMECONST
 
+define LINUX_TRY_PATCH_ARCH_S390_SSP
+	@if patch -p1 --dry-run -f -s -d $(@D) <$(LINUX_PKGDIR)/0002-arch-s390-disable-SSP-when-needed.patch.conditional >/dev/null ; then \
+		$(APPLY_PATCHES) $(@D) $(LINUX_PKGDIR) 0002-arch-s390-disable-SSP-when-needed.patch.conditional ; \
+	fi
+endef
+LINUX_POST_PATCH_HOOKS += LINUX_TRY_PATCH_ARCH_S390_SSP
+
 LINUX_KERNEL_CUSTOM_LOGO_PATH = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_LOGO_PATH))
 ifneq ($(LINUX_KERNEL_CUSTOM_LOGO_PATH),)
 LINUX_DEPENDENCIES += host-imagemagick
-- 
2.30.2