Hi,
On 14/01/2025 04:25, Volodymyr Babchuk wrote:
Enable previously added CONFIG_STACK_PROTECTOR feature for ARM
platform. We initialize stack protector very early, in head.S using
boot_stack_chk_guard_setup. This ensures that all C code from the very
beginning can use stack protector.
Signed-off-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
---
In v4:
- setup.c does not call boot_stack_chk_guard_setup() anymore, because
the original implementation was removed and
boot_stack_chk_guard_setup_early was renamed to boot_stack_chk_guard_setup
In v3:
- Call boot_stack_chk_guard_setup_early from head.S to ensure
that stack is protected from early boot stages
- Call boot_stack_chk_guard_setup() later, when time subsystem is
sufficiently initialized to provide values for the random number
generator.
In v2:
- Reordered Kconfig entry
---
xen/arch/arm/Kconfig | 1 +
xen/arch/arm/arm64/head.S | 3 +++
2 files changed, 4 insertions(+)
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index a26d3e1182..8f1a3c7d74 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -16,6 +16,7 @@ config ARM
select GENERIC_UART_INIT
select HAS_ALTERNATIVE if HAS_VMAP
select HAS_DEVICE_TREE
+ select HAS_STACK_PROTECTOR
This is select stack protection for both 32-bit and 64-bit. Yet...
select HAS_UBSAN
config ARCH_DEFCONFIG
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
... you only modify arm64. Why?
index 72c7b24498..5cbd62af86 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -250,6 +250,9 @@ real_start_efi:
#endif
PRINT("- Boot CPU booting -\r\n")
+#ifdef CONFIG_STACK_PROTECTOR
+ bl boot_stack_chk_guard_setup
+#endif
I don't think you can call a C function this early:
* The stack is not set (it is not clear why would the function not
use it)
* The MMU is not turned on
* We don't follow the AAPCS
If you want to call from assembly, then I think it just needs to be
called before launch.
Cheers,
--
Julien Grall
