[PATCH v3 1/1] firmware: Initialize stack guard via Zkr

[Xiang W]

在 2026-01-04日的 12:07 +0800，Xiang W写道：
> Try to initialize stack protection guard via the zkr extension.
> 
> Signed-off-by: Xiang W <wxjstz at 126.com>
> ---
>  firmware/fw_base.S           | 24 ++++++++++++++++++++++++
>  include/sbi/riscv_encoding.h | 10 ++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/firmware/fw_base.S b/firmware/fw_base.S
> index bce9e226..16e2e283 100644
> --- a/firmware/fw_base.S
> +++ b/firmware/fw_base.S
> @@ -107,6 +107,30 @@ _bss_zero:
>  	add	s4, s4, __SIZEOF_POINTER__
>  	blt	s4, s5, _bss_zero
>  
> +	/* Trying to initialize the stack guard via the Zkr extension */
> +	lla	t0, __stack_chk_guard_done
> +	csrw	CSR_MTVEC, t0
> +	li	t0, 0
> +	li	t3, SEED_OPTS_ES16
> +	li	t4, SEED_ENTROPY_MASK
> +	li	t5, __SIZEOF_POINTER__
> +__stack_chk_guard_loop:
> +	csrrw	t1, CSR_SEED, x0
> +	li	t2, SEED_OPTS_MASK
> +	andi	t2, t2, t1
s/addi/add/
new patch at https://lists.infradead.org/pipermail/opensbi/2026-January/009303.html

Regards,
Xiang W
> +	bgtu	t2, t3, __stack_chk_guard_done
> +	bltu	t2, t3, __stack_chk_guard_loop
> +	and	t1, t1, t4
> +	slli	t0, t0, 16
> +	or	t0, t0, t1
> +	addi	t5, t5, -2
> +	bgtz	t5, __stack_chk_guard_loop
> +	lla	t1, __stack_chk_guard
> +	REG_S	t0, 0(t1)
> +	j	__stack_chk_guard_done
> +	.align 3
> +__stack_chk_guard_done:
> +
>  	/* Setup temporary trap handler */
>  	lla	s4, _start_hang
>  	csrw	CSR_MTVEC, s4
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index b5a4ce81..3c1d5256 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -261,6 +261,16 @@
>  #define CSR_FRM				0x002
>  #define CSR_FCSR			0x003
>  
> +/* User entropy source */
> +#define CSR_SEED			0x015
> +#define SEED_OPTS_SHIFT			30
> +#define SEED_OPTS_MASK			(_UL(3) << SEED_OPTS_SHIFT)
> +#define SEED_OPTS_BIST			(_UL(0) << SEED_OPTS_SHIFT)
> +#define SEED_OPTS_WAIT			(_UL(1) << SEED_OPTS_SHIFT)
> +#define SEED_OPTS_ES16			(_UL(2) << SEED_OPTS_SHIFT)
> +#define SEED_OPTS_DEAD			(_UL(3) << SEED_OPTS_SHIFT)
> +#define SEED_ENTROPY_MASK		0xffff
> +
>  /* User Counters/Timers */
>  #define CSR_CYCLE			0xc00
>  #define CSR_TIME			0xc01
> -- 
> 2.47.3
>