kernel: 5.4: import wireguard backport

Rather than using the clunky, old, slower wireguard-linux-compat out of
tree module, this commit does a patch-by-patch backport of upstream's
wireguard to 5.4. This specific backport is in widespread use, being
part of SUSE's enterprise kernel, Oracle's enterprise kernel, Google's
Android kernel, Gentoo's distro kernel, and probably more I've forgotten
about. It's definately the "more proper" way of adding wireguard to a
kernel than the ugly compat.h hell of the wireguard-linux-compat repo.
And most importantly for OpenWRT, it allows using the same module
configuration code for 5.10 as for 5.4, with no need for bifurcation.

These patches are from the backport tree which is maintained in the
open here: https://git.zx2c4.com/wireguard-linux/log/?h=backport-5.4.y
I'll be sending PRs to update this as needed.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 108 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0009-crypto-arm-chacha-expose-ARM-ChaCha-routine-as-libra.patch b/target/linux/generic/backport-5.4/080-wireguard-0009-crypto-arm-chacha-expose-ARM-ChaCha-routine-as-libra.patch
new file mode 100644
index 0000000000..072b50b498
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0009-crypto-arm-chacha-expose-ARM-ChaCha-routine-as-libra.patch
@@ -0,0 +1,108 @@
+From 360be1a8f326ec5c0d20a134e228fb96a2eb351d Mon Sep 17 00:00:00 2001
+From: Ard Biesheuvel <ardb@kernel.org>
+Date: Fri, 8 Nov 2019 13:22:15 +0100
+Subject: [PATCH 009/124] crypto: arm/chacha - expose ARM ChaCha routine as
+ library function
+
+commit a44a3430d71bad4ee56788a59fff099b291ea54c upstream.
+
+Expose the accelerated NEON ChaCha routine directly as a symbol
+export so that users of the ChaCha library API can use it directly.
+
+Given that calls into the library API will always go through the
+routines in this module if it is enabled, switch to static keys
+to select the optimal implementation available (which may be none
+at all, in which case we defer to the generic implementation for
+all invocations).
+
+Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
+Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
+Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
+---
+ arch/arm/crypto/Kconfig       |  1 +
+ arch/arm/crypto/chacha-glue.c | 41 ++++++++++++++++++++++++++++++++++-
+ 2 files changed, 41 insertions(+), 1 deletion(-)
+
+--- a/arch/arm/crypto/Kconfig
++++ b/arch/arm/crypto/Kconfig
+@@ -129,6 +129,7 @@ config CRYPTO_CRC32_ARM_CE
+ config CRYPTO_CHACHA20_NEON
+ 	tristate "NEON and scalar accelerated ChaCha stream cipher algorithms"
+ 	select CRYPTO_BLKCIPHER
++	select CRYPTO_ARCH_HAVE_LIB_CHACHA
+ 
+ config CRYPTO_NHPOLY1305_NEON
+ 	tristate "NEON accelerated NHPoly1305 hash function (for Adiantum)"
+--- a/arch/arm/crypto/chacha-glue.c
++++ b/arch/arm/crypto/chacha-glue.c
+@@ -11,6 +11,7 @@
+ #include <crypto/internal/chacha.h>
+ #include <crypto/internal/simd.h>
+ #include <crypto/internal/skcipher.h>
++#include <linux/jump_label.h>
+ #include <linux/kernel.h>
+ #include <linux/module.h>
+ 
+@@ -29,9 +30,11 @@ asmlinkage void hchacha_block_neon(const
+ asmlinkage void chacha_doarm(u8 *dst, const u8 *src, unsigned int bytes,
+ 			     const u32 *state, int nrounds);
+ 
++static __ro_after_init DEFINE_STATIC_KEY_FALSE(use_neon);
++
+ static inline bool neon_usable(void)
+ {
+-	return crypto_simd_usable();
++	return static_branch_likely(&use_neon) && crypto_simd_usable();
+ }
+ 
+ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
+@@ -60,6 +63,40 @@ static void chacha_doneon(u32 *state, u8
+ 	}
+ }
+ 
++void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
++{
++	if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable()) {
++		hchacha_block_arm(state, stream, nrounds);
++	} else {
++		kernel_neon_begin();
++		hchacha_block_neon(state, stream, nrounds);
++		kernel_neon_end();
++	}
++}
++EXPORT_SYMBOL(hchacha_block_arch);
++
++void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
++{
++	chacha_init_generic(state, key, iv);
++}
++EXPORT_SYMBOL(chacha_init_arch);
++
++void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, unsigned int bytes,
++		       int nrounds)
++{
++	if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon_usable() ||
++	    bytes <= CHACHA_BLOCK_SIZE) {
++		chacha_doarm(dst, src, bytes, state, nrounds);
++		state[12] += DIV_ROUND_UP(bytes, CHACHA_BLOCK_SIZE);
++		return;
++	}
++
++	kernel_neon_begin();
++	chacha_doneon(state, dst, src, bytes, nrounds);
++	kernel_neon_end();
++}
++EXPORT_SYMBOL(chacha_crypt_arch);
++
+ static int chacha_stream_xor(struct skcipher_request *req,
+ 			     const struct chacha_ctx *ctx, const u8 *iv,
+ 			     bool neon)
+@@ -269,6 +306,8 @@ static int __init chacha_simd_mod_init(v
+ 			for (i = 0; i < ARRAY_SIZE(neon_algs); i++)
+ 				neon_algs[i].base.cra_priority = 0;
+ 			break;
++		default:
++			static_branch_enable(&use_neon);
+ 		}
+ 
+ 		err = crypto_register_skciphers(neon_algs, ARRAY_SIZE(neon_algs));