[PATCH] firmware: generate __stack_chk_guard at compile time

[Xiang W]

Replace 0x95B5FF5A with a random number generated by Python during
compilation as the __stack_chk_guard.

Signed-off-by: Xiang W <wangxiang at iscas.ac.cn>
---
 firmware/fw_base.S            | 2 +-
 firmware/objects.mk           | 7 +++++++
 firmware/payloads/test_head.S | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/firmware/fw_base.S b/firmware/fw_base.S
index 63bb4473..040fbd2b 100644
--- a/firmware/fw_base.S
+++ b/firmware/fw_base.S
@@ -779,7 +779,7 @@ __stack_chk_fail:
 	.globl __stack_chk_guard
 	.type __stack_chk_guard, %object
 __stack_chk_guard:
-	RISCV_PTR	0x95B5FF5A
+	RISCV_PTR	STACK_CHK_GUARD
 
 #ifdef FW_FDT_PATH
 	.section .rodata
diff --git a/firmware/objects.mk b/firmware/objects.mk
index bfec4671..c4dad9ba 100644
--- a/firmware/objects.mk
+++ b/firmware/objects.mk
@@ -75,3 +75,10 @@ else
 stack-protector-cflags-y := -fno-stack-protector
 endif
 firmware-cflags-y += $(stack-protector-cflags-y)
+
+ifeq ($(PLATFORM_RISCV_XLEN),32)
+STACK_CHK_GUARD := $(shell python3 -c 'import random; print(random.randint(1, 0xffffffff))')
+else
+STACK_CHK_GUARD := $(shell python3 -c 'import random; print(random.randint(1, 0xffffffffffffffff))')
+endif
+firmware-genflags-y += -DSTACK_CHK_GUARD=$(STACK_CHK_GUARD)
diff --git a/firmware/payloads/test_head.S b/firmware/payloads/test_head.S
index 9a87e56f..fdc1deb9 100644
--- a/firmware/payloads/test_head.S
+++ b/firmware/payloads/test_head.S
@@ -111,4 +111,4 @@ _boot_a1:
 	.globl __stack_chk_guard
 	.type __stack_chk_guard, %object
 __stack_chk_guard:
-	RISCV_PTR	0x95B5FF5A
+	RISCV_PTR	STACK_CHK_GUARD
-- 
2.47.3