board/qemu: add xtensa kernel patch

-fno-stack-protector must 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/buildroot.org/toolchains-builder/-/jobs/15876432953

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Julien Olivain <ju.o@free.fr>

board/qemu/xtensa-lx60/patches/linux/0001-xtensa-disable-SSP-when-needed.patch

@@ -0,0 +1,36 @@
+From 5358d4e20801ffbb1c0834eab36c003049d4055f Mon Sep 17 00:00:00 2001
+From: Romain Naour <romain.naour@smile.fr>
+Date: Sun, 16 Aug 2026 22:27:28 +0200
+Subject: [PATCH] xtensa: disable SSP when needed
+
+-fno-stack-protector must 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/buildroot.org/toolchains-builder/-/jobs/15876432953
+
+Upstream: Submitted to Max Filippov via email for initial review.
+
+Cc: Max Filippov <jcmvbkbc@gmail.com>
+Signed-off-by: Romain Naour <romain.naour@smile.fr>
+---
+ arch/xtensa/boot/Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/xtensa/boot/Makefile b/arch/xtensa/boot/Makefile
+index d8b0fadf429a9..dfb758cdb2756 100644
+--- a/arch/xtensa/boot/Makefile
++++ b/arch/xtensa/boot/Makefile
+@@ -9,7 +9,7 @@
+ 
+ 
+ # KBUILD_CFLAGS used when building rest of boot (takes effect recursively)
+-KBUILD_CFLAGS	+= -fno-builtin
++KBUILD_CFLAGS	+= -fno-builtin -fno-stack-protector
+ 
+ subdir-y	:= lib
+ targets		+= vmlinux.bin vmlinux.bin.gz
+-- 
+2.55.0
+

configs/qemu_xtensa_lx60_defconfig

@@ -2,7 +2,7 @@ BR2_xtensa=y
 BR2_XTENSA_CUSTOM=y
 BR2_XTENSA_OVERLAY_FILE="https://github.com/jcmvbkbc/xtensa-toolchain-build/raw/95291b7c39e6f790d0b2f062c945a630290f2c81/overlays/xtensa_dc233c.tar.gz"
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_18=y
-BR2_GLOBAL_PATCH_DIR="board/qemu/patches"
+BR2_GLOBAL_PATCH_DIR="board/qemu/patches board/qemu/xtensa-lx60/patches"
 BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_SYSTEM_DHCP="eth0"

configs/qemu_xtensa_lx60_nommu_defconfig

@@ -3,7 +3,7 @@ BR2_XTENSA_CUSTOM=y
 BR2_XTENSA_OVERLAY_FILE="https://github.com/jcmvbkbc/xtensa-toolchain-build/raw/95291b7c39e6f790d0b2f062c945a630290f2c81/overlays/xtensa_dc233c.tar.gz"
 # BR2_XTENSA_USE_MMU is not set
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_18=y
-BR2_GLOBAL_PATCH_DIR="board/qemu/patches"
+BR2_GLOBAL_PATCH_DIR="board/qemu/patches board/qemu/xtensa-lx60/patches"
 BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_SYSTEM_DHCP="eth0"