linux-kernel - [PATCH AUTOSEL 5.15 12/27] crypto: x86/chacha20 - Avoid spurious jumps to other functions

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Date:   Wed,  6 Apr 2022 21:12:42 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Martin Willi <martin@...ongswan.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Sasha Levin <sashal@...nel.org>, davem@...emloft.net,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org,
        linux-crypto@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 12/27] crypto: x86/chacha20 - Avoid spurious jumps to other functions

From: Peter Zijlstra <peterz@...radead.org>

[ Upstream commit 4327d168515fd8b5b92fa1efdf1d219fb6514460 ]

The chacha_Nblock_xor_avx512vl() functions all have their own,
identical, .LdoneN label, however in one particular spot {2,4} jump to
the 8 version instead of their own. Resulting in:

  arch/x86/crypto/chacha-x86_64.o: warning: objtool: chacha_2block_xor_avx512vl() falls through to next function chacha_8block_xor_avx512vl()
  arch/x86/crypto/chacha-x86_64.o: warning: objtool: chacha_4block_xor_avx512vl() falls through to next function chacha_8block_xor_avx512vl()

Make each function consistently use its own done label.

Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Martin Willi <martin@...ongswan.org>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/crypto/chacha-avx512vl-x86_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/crypto/chacha-avx512vl-x86_64.S b/arch/x86/crypto/chacha-avx512vl-x86_64.S
index bb193fde123a..8713c16c2501 100644
--- a/arch/x86/crypto/chacha-avx512vl-x86_64.S
+++ b/arch/x86/crypto/chacha-avx512vl-x86_64.S
@@ -172,7 +172,7 @@ SYM_FUNC_START(chacha_2block_xor_avx512vl)
 	# xor remaining bytes from partial register into output
 	mov		%rcx,%rax
 	and		$0xf,%rcx
-	jz		.Ldone8
+	jz		.Ldone2
 	mov		%rax,%r9
 	and		$~0xf,%r9
 
@@ -438,7 +438,7 @@ SYM_FUNC_START(chacha_4block_xor_avx512vl)
 	# xor remaining bytes from partial register into output
 	mov		%rcx,%rax
 	and		$0xf,%rcx
-	jz		.Ldone8
+	jz		.Ldone4
 	mov		%rax,%r9
 	and		$~0xf,%r9
 
-- 
2.35.1