From da4d5933e30340766925480f9dd9f250c4355e24 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 1 Oct 2026 20:44:05 -0700 Subject: [PATCH] lib/crypto: x86/aes-ctr: Remove some unreachable code In the AES-CTR and AES-XCTR code that handles a remainder of '4*VL < LEN < 8*VL', first 4 full vectors are processed, leaving 0 < LEN < 4*VL. After that, five different cases are handled depending on whether there are 0, 1, 2, 3, or 4 full vectors remaining. But the case of 4 vectors is never reached there, making the code handling it unused. Remove it. With that done, the '.Lxor_tail_partial_vec_3\@' block would be reached only via an unconditional jump. Therefore, relocate it to the only place that jumps to it. This allows removing the jump at the end of the '.Lxor_tail_partial_vec_2\@' block and making it fall through. Reviewed-by: Ard Biesheuvel Link: https://patch.msgid.link/20261002034405.49886-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- lib/crypto/x86/aes-ctr-avx-x86_64.S | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/lib/crypto/x86/aes-ctr-avx-x86_64.S b/lib/crypto/x86/aes-ctr-avx-x86_64.S index c232337899b6..13b3e2cfae37 100644 --- a/lib/crypto/x86/aes-ctr-avx-x86_64.S +++ b/lib/crypto/x86/aes-ctr-avx-x86_64.S @@ -419,10 +419,12 @@ cmp $3*VL-1, LEN32 jle .Lxor_tail_partial_vec_2\@ _xor_data 2 - cmp $4*VL-1, LEN32 - jle .Lxor_tail_partial_vec_3\@ - _xor_data 3 - jmp .Ldone\@ + add $-3*VL, LEN32 + jz .Ldone\@ + sub $-3*VL, SRC + sub $-3*VL, DST + _vmovdqa AESDATA3, AESDATA0 + jmp .Lxor_tail_partial_vec_0\@ .Lenc_tail_atmost4vecs\@: cmp $2*VL, LEN32 @@ -469,14 +471,6 @@ sub $-2*VL, SRC sub $-2*VL, DST _vmovdqa AESDATA2, AESDATA0 - jmp .Lxor_tail_partial_vec_0\@ - -.Lxor_tail_partial_vec_3\@: - add $-3*VL, LEN32 - jz .Ldone\@ - sub $-3*VL, SRC - sub $-3*VL, DST - _vmovdqa AESDATA3, AESDATA0 .Lxor_tail_partial_vec_0\@: // XOR the remaining 1 <= LEN < VL bytes. It's easy if masked