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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Sasha Levin <sashal@kernel.org>,
	linux-crypto@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 5.5 092/542] crypto: arm/chacha - fix build failured when kernel mode NEON is disabled
Date: Fri, 14 Feb 2020 10:41:24 -0500
Message-ID: <20200214154854.6746-92-sashal@kernel.org> (raw)
In-Reply-To: <20200214154854.6746-1-sashal@kernel.org>

From: Ard Biesheuvel <ardb@kernel.org>

[ Upstream commit 0bc81767c5bd9d005fae1099fb39eb3688370cb1 ]

When the ARM accelerated ChaCha driver is built as part of a configuration
that has kernel mode NEON disabled, we expect the compiler to propagate
the build time constant expression IS_ENABLED(CONFIG_KERNEL_MODE_NEON) in
a way that eliminates all the cross-object references to the actual NEON
routines, which allows the chacha-neon-core.o object to be omitted from
the build entirely.

Unfortunately, this fails to work as expected in some cases, and we may
end up with a build error such as

  chacha-glue.c:(.text+0xc0): undefined reference to `chacha_4block_xor_neon'

caused by the fact that chacha_doneon() has not been eliminated from the
object code, even though it will never be called in practice.

Let's fix this by adding some IS_ENABLED(CONFIG_KERNEL_MODE_NEON) tests
that are not strictly needed from a logical point of view, but should
help the compiler infer that the NEON code paths are unreachable in
those cases.

Fixes: b36d8c09e710c71f ("crypto: arm/chacha - remove dependency on generic ...")
Reported-by: Russell King <linux@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/arm/crypto/chacha-glue.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/crypto/chacha-glue.c b/arch/arm/crypto/chacha-glue.c
index 6ebbb2b241d2b..6fdb0ac62b3d8 100644
--- a/arch/arm/crypto/chacha-glue.c
+++ b/arch/arm/crypto/chacha-glue.c
@@ -115,7 +115,7 @@ static int chacha_stream_xor(struct skcipher_request *req,
 		if (nbytes < walk.total)
 			nbytes = round_down(nbytes, walk.stride);
 
-		if (!neon) {
+		if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon) {
 			chacha_doarm(walk.dst.virt.addr, walk.src.virt.addr,
 				     nbytes, state, ctx->nrounds);
 			state[12] += DIV_ROUND_UP(nbytes, CHACHA_BLOCK_SIZE);
@@ -159,7 +159,7 @@ static int do_xchacha(struct skcipher_request *req, bool neon)
 
 	chacha_init_generic(state, ctx->key, req->iv);
 
-	if (!neon) {
+	if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon) {
 		hchacha_block_arm(state, subctx.key, ctx->nrounds);
 	} else {
 		kernel_neon_begin();
-- 
2.20.1


  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200214154854.6746-1-sashal@kernel.org>
2020-02-14 15:40 ` [PATCH AUTOSEL 5.5 017/542] crypto: testmgr - don't try to decrypt uninitialized buffers Sasha Levin
2020-02-14 15:41 ` Sasha Levin [this message]
2020-02-14 15:43 ` [PATCH AUTOSEL 5.5 193/542] padata: validate cpumask without removed CPU during offline Sasha Levin
2020-02-14 15:43 ` [PATCH AUTOSEL 5.5 194/542] padata: always acquire cpu_hotplug_lock before pinst->lock Sasha Levin
2020-02-14 15:43 ` [PATCH AUTOSEL 5.5 242/542] crypto: inside-secure - add unspecified HAS_IOMEM dependency Sasha Levin
2020-02-14 15:43 ` [PATCH AUTOSEL 5.5 243/542] crypto: amlogic " Sasha Levin
2020-02-14 15:44 ` [PATCH AUTOSEL 5.5 265/542] crypto: chtls - Fixed memory leak Sasha Levin
2020-02-14 15:44 ` [PATCH AUTOSEL 5.5 303/542] crypto: artpec6 - return correct error code for failed setkey() Sasha Levin
2020-02-14 15:44 ` [PATCH AUTOSEL 5.5 304/542] crypto: atmel-sha - fix error handling when setting hmac key Sasha Levin
2020-02-14 15:46 ` [PATCH AUTOSEL 5.5 378/542] crypto: hisilicon - Update debugfs usage of SEC V2 Sasha Levin
2020-02-14 15:46 ` [PATCH AUTOSEL 5.5 379/542] crypto: hisilicon - Bugfixed tfm leak Sasha Levin
2020-02-14 15:46 ` [PATCH AUTOSEL 5.5 380/542] crypto: essiv - fix AEAD capitalization and preposition use in help text Sasha Levin

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