From 8f0c4ae3f94ccdb87fb46fdb5c3dffe3e7cedaaa Mon Sep 17 00:00:00 2001
From: Bill Nguyen <bill.nguyen@unsw.edu.au>
Date: Mon, 28 Sep 2026 13:53:50 +1000
Subject: [PATCH] libmicrokit,loader,monitor: omit stack protector

Some distro-packaged compilers enable Stack Smashing Protection (SSP)
by default, even with -ffreestanding.

If you build Microkit with such a compiler for the same architecture as
your host (i.e. using the native rather than a cross toolchain), linking
fails with:

```
ld.lld: error: undefined symbol: __stack_chk_fail
>>> referenced by util.c:0 (... /monitor/src/util.c:0)
...
```

This is fixed this by building libmicrokit, loader and monitor with
-fno-stack-protector.

Signed-off-by: Bill Nguyen <bill.nguyen@unsw.edu.au>
---
 libmicrokit/Makefile | 1 +
 loader/Makefile      | 2 +-
 monitor/Makefile     | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/libmicrokit/Makefile b/libmicrokit/Makefile
index 334ecf504..b3134f1a1 100644
--- a/libmicrokit/Makefile
+++ b/libmicrokit/Makefile
@@ -50,6 +50,7 @@ endif
 CFLAGS := -std=gnu11 \
 		  -g -O3 -nostdlib \
 		  -ffreestanding \
+		  -fno-stack-protector \
 		  -Wall $(CFLAGS_TOOLCHAIN) \
 		  -Wno-unused-function -Werror \
 		  -Iinclude -I$(SEL4_SDK)/include \
diff --git a/loader/Makefile b/loader/Makefile
index c08c18bd9..4a2979131 100644
--- a/loader/Makefile
+++ b/loader/Makefile
@@ -47,7 +47,7 @@ else ifeq ($(ARCH),riscv64)
 	ARCH_DIR := riscv
 endif
 
-CFLAGS := -std=gnu11 -g -O3 -nostdlib -ffreestanding \
+CFLAGS := -std=gnu11 -g -O3 -nostdlib -ffreestanding -fno-stack-protector \
 					-MP -MD $(CFLAGS_ARCH) -DBOARD_$(BOARD) -I$(SEL4_SDK)/include \
 					-Wall -Werror -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations \
 					-Wundef -Wno-nonnull -Wnested-externs
diff --git a/monitor/Makefile b/monitor/Makefile
index 1223795a1..5e51d17c0 100644
--- a/monitor/Makefile
+++ b/monitor/Makefile
@@ -53,7 +53,7 @@ else
 	$(error ARCH is unsupported)
 endif
 
-CFLAGS := -std=gnu11 -g -O3 -nostdlib -ffreestanding -Wall $(CFLAGS_TOOLCHAIN) -Werror -I$(SEL4_SDK)/include $(CFLAGS_ARCH) -DARCH_$(ARCH)
+CFLAGS := -std=gnu11 -g -O3 -nostdlib -ffreestanding -fno-stack-protector -Wall $(CFLAGS_TOOLCHAIN) -Werror -I$(SEL4_SDK)/include $(CFLAGS_ARCH) -DARCH_$(ARCH)
 
 PROGS := monitor.elf
 OBJECTS := main.o crt0.o util.o