The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 43169328c7b4623b54b7713ec68479cebda5465f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025122944-stonewall-evoke-f7f0@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 43169328c7b4623b54b7713ec68479cebda5465f Mon Sep 17 00:00:00 2001 From: Vivian Wang wangruikang@iscas.ac.cn Date: Tue, 2 Dec 2025 13:25:07 +0800 Subject: [PATCH] lib/crypto: riscv/chacha: Avoid s0/fp register

In chacha_zvkb, avoid using the s0 register, which is the frame pointer, by reallocating KEY0 to t5. This makes stack traces available if e.g. a crash happens in chacha_zvkb.

No frame pointer maintenance is otherwise required since this is a leaf function.

Signed-off-by: Vivian Wang wangruikang@iscas.ac.cn Fixes: bb54668837a0 ("crypto: riscv - add vector crypto accelerated ChaCha20") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20251202-riscv-chacha_zvkb-fp-v2-1-7bd00098c9dc@is... Signed-off-by: Eric Biggers ebiggers@kernel.org

diff --git a/lib/crypto/riscv/chacha-riscv64-zvkb.S b/lib/crypto/riscv/chacha-riscv64-zvkb.S index b777d0b4e379..3d183ec818f5 100644 --- a/lib/crypto/riscv/chacha-riscv64-zvkb.S +++ b/lib/crypto/riscv/chacha-riscv64-zvkb.S @@ -60,7 +60,8 @@ #define VL t2 #define STRIDE t3 #define ROUND_CTR t4 -#define KEY0 s0 +#define KEY0 t5 +// Avoid s0/fp to allow for unwinding #define KEY1 s1 #define KEY2 s2 #define KEY3 s3 @@ -143,7 +144,6 @@ // The updated 32-bit counter is written back to state->x[12] before returning. SYM_FUNC_START(chacha_zvkb) addi sp, sp, -96 - sd s0, 0(sp) sd s1, 8(sp) sd s2, 16(sp) sd s3, 24(sp) @@ -280,7 +280,6 @@ SYM_FUNC_START(chacha_zvkb) bnez NBLOCKS, .Lblock_loop

sw COUNTER, 48(STATEP) - ld s0, 0(sp) ld s1, 8(sp) ld s2, 16(sp) ld s3, 24(sp)