Commit 43169328 authored by Vivian Wang's avatar Vivian Wang Committed by Eric Biggers
Browse files

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: default avatarVivian Wang <wangruikang@iscas.ac.cn>
Fixes: bb546688 ("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@iscas.ac.cn


Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
parent 7a3984bb

lib/crypto/riscv/chacha-riscv64-zvkb.S

+2 −3
Original line number Diff line number Diff line
@@ -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)