* [PATCH v3 1/1] firmware: Initialize stack guard via Zkr
@ 2026-01-04 4:07 Xiang W
2026-01-04 5:25 ` Xiang W
0 siblings, 1 reply; 2+ messages in thread
From: Xiang W @ 2026-01-04 4:07 UTC (permalink / raw)
To: opensbi; +Cc: Xiang W, anup
Try to initialize stack protection guard via the zkr extension.
Signed-off-by: Xiang W <wxjstz@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
+ 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
--
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3 1/1] firmware: Initialize stack guard via Zkr
2026-01-04 4:07 [PATCH v3 1/1] firmware: Initialize stack guard via Zkr Xiang W
@ 2026-01-04 5:25 ` Xiang W
0 siblings, 0 replies; 2+ messages in thread
From: Xiang W @ 2026-01-04 5:25 UTC (permalink / raw)
To: opensbi; +Cc: anup
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@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
>
--
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http://lists.infradead.org/mailman/listinfo/opensbi
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