Re: [PATCH v5 2/4] xen: common: add ability to enable stack protector

[Julien Grall <julien@xxxxxxx>]

Hi Volodymyr,

On 13/02/2025 22:00, Volodymyr Babchuk wrote:
> diff --git a/xen/common/stack-protector.c b/xen/common/stack-protector.c
> new file mode 100644
> index 0000000000..286753a1b1
> --- /dev/null
> +++ b/xen/common/stack-protector.c
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#include <xen/init.h>
> +#include <xen/lib.h>
> +#include <xen/random.h>
> +#include <xen/time.h>
> +
> +/*
> + * Initial value is chosen by a fair dice roll.
> + * It will be updated during boot process.
> + */
> +#if BITS_PER_LONG == 32
> +unsigned long __ro_after_init __stack_chk_guard = 0xdd2cc927UL;
> +#else
> +unsigned long __ro_after_init __stack_chk_guard = 0x2d853605a4d9a09cUL;
> +#endif
> +
> +/*
> + * This function should be called from early asm or from a C function
> + * that escapes stack canary tracking (by calling
> + * reset_stack_and_jump() for example).
> + */
> +void __init asmlinkage boot_stack_chk_guard_setup(void)
I am probably missing something. But what prevent the compiler to insert 
a stack guard when entering this function and checking on exit? Wouldn't 
this fail because __stack_chk_guard would be different?
IOW, shouldn't this function be a static always inline like it used to be?

Cheers,

--
Julien Grall