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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
To:     linux-crypto@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        David Miller <davem@davemloft.net>,
        Greg KH <gregkh@linuxfoundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Jason A . Donenfeld" <Jason@zx2c4.com>,
        Samuel Neves <sneves@dei.uc.pt>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Eric Biggers <ebiggers@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: [RFC PATCH 11/18] int128: move __uint128_t compiler test to Kconfig
Date:   Wed, 25 Sep 2019 18:12:48 +0200
Message-Id: <20190925161255.1871-12-ard.biesheuvel@linaro.org>
In-Reply-To: <20190925161255.1871-1-ard.biesheuvel@linaro.org>
References: <20190925161255.1871-1-ard.biesheuvel@linaro.org>
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In order to use 128-bit integer arithmetic in C code, the architecture
needs to have declared support for it by setting ARCH_SUPPORTS_INT128,
and it requires a version of the toolchain that supports this at build
time. This is why all existing tests for ARCH_SUPPORTS_INT128 also test
whether __SIZEOF_INT128__ is defined, since this is only the case for
compilers that can support 128-bit integers.

Let's fold this additional test into the Kconfig declaration of
ARCH_SUPPORTS_INT128 so that we can also use the symbol in Makefiles,
e.g., to decide whether a certain object needs to be included in the
first place.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 crypto/ecc.c | 2 +-
 init/Kconfig | 1 +
 lib/ubsan.c  | 2 +-
 lib/ubsan.h  | 2 +-
 4 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index dfe114bc0c4a..6e6aab6c987c 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -336,7 +336,7 @@ static u64 vli_usub(u64 *result, const u64 *left, u64 right,
 static uint128_t mul_64_64(u64 left, u64 right)
 {
 	uint128_t result;
-#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+#if defined(CONFIG_ARCH_SUPPORTS_INT128)
 	unsigned __int128 m = (unsigned __int128)left * right;
 
 	result.m_low  = m;
diff --git a/init/Kconfig b/init/Kconfig
index bd7d650d4a99..e66f64a26d7d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -785,6 +785,7 @@ config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 #
 config ARCH_SUPPORTS_INT128
 	bool
+	depends on !$(cc-option,-D__SIZEOF_INT128__=0)
 
 # For architectures that (ab)use NUMA to represent different memory regions
 # all cpu-local but of different latencies, such as SuperH.
diff --git a/lib/ubsan.c b/lib/ubsan.c
index e7d31735950d..b652cc14dd60 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -119,7 +119,7 @@ static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 {
 	if (type_is_int(type)) {
 		if (type_bit_width(type) == 128) {
-#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+#if defined(CONFIG_ARCH_SUPPORTS_INT128)
 			u_max val = get_unsigned_val(type, value);
 
 			scnprintf(str, size, "0x%08x%08x%08x%08x",
diff --git a/lib/ubsan.h b/lib/ubsan.h
index b8fa83864467..7b56c09473a9 100644
--- a/lib/ubsan.h
+++ b/lib/ubsan.h
@@ -78,7 +78,7 @@ struct invalid_value_data {
 	struct type_descriptor *type;
 };
 
-#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+#if defined(CONFIG_ARCH_SUPPORTS_INT128)
 typedef __int128 s_max;
 typedef unsigned __int128 u_max;
 #else
-- 
2.20.1