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, 205 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/080-wireguard-0004-crypto-x86-chacha-expose-SIMD-ChaCha-routine-as-libr.patch b/target/linux/generic/backport-5.4/080-wireguard-0004-crypto-x86-chacha-expose-SIMD-ChaCha-routine-as-libr.patch
new file mode 100644
index 0000000000..0e916c88cf
--- /dev/null
+++ b/target/linux/generic/backport-5.4/080-wireguard-0004-crypto-x86-chacha-expose-SIMD-ChaCha-routine-as-libr.patch
@@ -0,0 +1,205 @@
+From e7f5b03590beee54da6d02aabe0e1392bc3251e4 Mon Sep 17 00:00:00 2001
+From: Ard Biesheuvel <ardb@kernel.org>
+Date: Fri, 8 Nov 2019 13:22:10 +0100
+Subject: [PATCH 004/124] crypto: x86/chacha - expose SIMD ChaCha routine as
+ library function
+
+commit 84e03fa39fbe95a5567d43bff458c6d3b3a23ad1 upstream.
+
+Wire the existing x86 SIMD ChaCha code into the new ChaCha library
+interface, so that users of the library interface will get the
+accelerated version when available.
+
+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/x86/crypto/chacha_glue.c | 91 +++++++++++++++++++++++++----------
+ crypto/Kconfig                |  1 +
+ include/crypto/chacha.h       |  6 +++
+ 3 files changed, 73 insertions(+), 25 deletions(-)
+
+--- a/arch/x86/crypto/chacha_glue.c
++++ b/arch/x86/crypto/chacha_glue.c
+@@ -21,24 +21,24 @@ asmlinkage void chacha_block_xor_ssse3(u
+ asmlinkage void chacha_4block_xor_ssse3(u32 *state, u8 *dst, const u8 *src,
+ 					unsigned int len, int nrounds);
+ asmlinkage void hchacha_block_ssse3(const u32 *state, u32 *out, int nrounds);
+-#ifdef CONFIG_AS_AVX2
++
+ asmlinkage void chacha_2block_xor_avx2(u32 *state, u8 *dst, const u8 *src,
+ 				       unsigned int len, int nrounds);
+ asmlinkage void chacha_4block_xor_avx2(u32 *state, u8 *dst, const u8 *src,
+ 				       unsigned int len, int nrounds);
+ asmlinkage void chacha_8block_xor_avx2(u32 *state, u8 *dst, const u8 *src,
+ 				       unsigned int len, int nrounds);
+-static bool chacha_use_avx2;
+-#ifdef CONFIG_AS_AVX512
++
+ asmlinkage void chacha_2block_xor_avx512vl(u32 *state, u8 *dst, const u8 *src,
+ 					   unsigned int len, int nrounds);
+ asmlinkage void chacha_4block_xor_avx512vl(u32 *state, u8 *dst, const u8 *src,
+ 					   unsigned int len, int nrounds);
+ asmlinkage void chacha_8block_xor_avx512vl(u32 *state, u8 *dst, const u8 *src,
+ 					   unsigned int len, int nrounds);
+-static bool chacha_use_avx512vl;
+-#endif
+-#endif
++
++static __ro_after_init DEFINE_STATIC_KEY_FALSE(chacha_use_simd);
++static __ro_after_init DEFINE_STATIC_KEY_FALSE(chacha_use_avx2);
++static __ro_after_init DEFINE_STATIC_KEY_FALSE(chacha_use_avx512vl);
+ 
+ static unsigned int chacha_advance(unsigned int len, unsigned int maxblocks)
+ {
+@@ -49,9 +49,8 @@ static unsigned int chacha_advance(unsig
+ static void chacha_dosimd(u32 *state, u8 *dst, const u8 *src,
+ 			  unsigned int bytes, int nrounds)
+ {
+-#ifdef CONFIG_AS_AVX2
+-#ifdef CONFIG_AS_AVX512
+-	if (chacha_use_avx512vl) {
++	if (IS_ENABLED(CONFIG_AS_AVX512) &&
++	    static_branch_likely(&chacha_use_avx512vl)) {
+ 		while (bytes >= CHACHA_BLOCK_SIZE * 8) {
+ 			chacha_8block_xor_avx512vl(state, dst, src, bytes,
+ 						   nrounds);
+@@ -79,8 +78,9 @@ static void chacha_dosimd(u32 *state, u8
+ 			return;
+ 		}
+ 	}
+-#endif
+-	if (chacha_use_avx2) {
++
++	if (IS_ENABLED(CONFIG_AS_AVX2) &&
++	    static_branch_likely(&chacha_use_avx2)) {
+ 		while (bytes >= CHACHA_BLOCK_SIZE * 8) {
+ 			chacha_8block_xor_avx2(state, dst, src, bytes, nrounds);
+ 			bytes -= CHACHA_BLOCK_SIZE * 8;
+@@ -104,7 +104,7 @@ static void chacha_dosimd(u32 *state, u8
+ 			return;
+ 		}
+ 	}
+-#endif
++
+ 	while (bytes >= CHACHA_BLOCK_SIZE * 4) {
+ 		chacha_4block_xor_ssse3(state, dst, src, bytes, nrounds);
+ 		bytes -= CHACHA_BLOCK_SIZE * 4;
+@@ -123,6 +123,43 @@ static void chacha_dosimd(u32 *state, u8
+ 	}
+ }
+ 
++void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
++{
++	state = PTR_ALIGN(state, CHACHA_STATE_ALIGN);
++
++	if (!static_branch_likely(&chacha_use_simd) || !crypto_simd_usable()) {
++		hchacha_block_generic(state, stream, nrounds);
++	} else {
++		kernel_fpu_begin();
++		hchacha_block_ssse3(state, stream, nrounds);
++		kernel_fpu_end();
++	}
++}
++EXPORT_SYMBOL(hchacha_block_arch);
++
++void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
++{
++	state = PTR_ALIGN(state, CHACHA_STATE_ALIGN);
++
++	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)
++{
++	state = PTR_ALIGN(state, CHACHA_STATE_ALIGN);
++
++	if (!static_branch_likely(&chacha_use_simd) || !crypto_simd_usable() ||
++	    bytes <= CHACHA_BLOCK_SIZE)
++		return chacha_crypt_generic(state, dst, src, bytes, nrounds);
++
++	kernel_fpu_begin();
++	chacha_dosimd(state, dst, src, bytes, nrounds);
++	kernel_fpu_end();
++}
++EXPORT_SYMBOL(chacha_crypt_arch);
++
+ static int chacha_simd_stream_xor(struct skcipher_request *req,
+ 				  const struct chacha_ctx *ctx, const u8 *iv)
+ {
+@@ -143,7 +180,8 @@ static int chacha_simd_stream_xor(struct
+ 		if (nbytes < walk.total)
+ 			nbytes = round_down(nbytes, walk.stride);
+ 
+-		if (!crypto_simd_usable()) {
++		if (!static_branch_likely(&chacha_use_simd) ||
++		    !crypto_simd_usable()) {
+ 			chacha_crypt_generic(state, walk.dst.virt.addr,
+ 					     walk.src.virt.addr, nbytes,
+ 					     ctx->nrounds);
+@@ -246,18 +284,21 @@ static struct skcipher_alg algs[] = {
+ static int __init chacha_simd_mod_init(void)
+ {
+ 	if (!boot_cpu_has(X86_FEATURE_SSSE3))
+-		return -ENODEV;
++		return 0;
+ 
+-#ifdef CONFIG_AS_AVX2
+-	chacha_use_avx2 = boot_cpu_has(X86_FEATURE_AVX) &&
+-			  boot_cpu_has(X86_FEATURE_AVX2) &&
+-			  cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
+-#ifdef CONFIG_AS_AVX512
+-	chacha_use_avx512vl = chacha_use_avx2 &&
+-			      boot_cpu_has(X86_FEATURE_AVX512VL) &&
+-			      boot_cpu_has(X86_FEATURE_AVX512BW); /* kmovq */
+-#endif
+-#endif
++	static_branch_enable(&chacha_use_simd);
++
++	if (IS_ENABLED(CONFIG_AS_AVX2) &&
++	    boot_cpu_has(X86_FEATURE_AVX) &&
++	    boot_cpu_has(X86_FEATURE_AVX2) &&
++	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL)) {
++		static_branch_enable(&chacha_use_avx2);
++
++		if (IS_ENABLED(CONFIG_AS_AVX512) &&
++		    boot_cpu_has(X86_FEATURE_AVX512VL) &&
++		    boot_cpu_has(X86_FEATURE_AVX512BW)) /* kmovq */
++			static_branch_enable(&chacha_use_avx512vl);
++	}
+ 	return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
+ }
+ 
+--- a/crypto/Kconfig
++++ b/crypto/Kconfig
+@@ -1418,6 +1418,7 @@ config CRYPTO_CHACHA20_X86_64
+ 	depends on X86 && 64BIT
+ 	select CRYPTO_BLKCIPHER
+ 	select CRYPTO_LIB_CHACHA_GENERIC
++	select CRYPTO_ARCH_HAVE_LIB_CHACHA
+ 	help
+ 	  SSSE3, AVX2, and AVX-512VL optimized implementations of the ChaCha20,
+ 	  XChaCha20, and XChaCha12 stream ciphers.
+--- a/include/crypto/chacha.h
++++ b/include/crypto/chacha.h
+@@ -25,6 +25,12 @@
+ #define CHACHA_BLOCK_SIZE	64
+ #define CHACHAPOLY_IV_SIZE	12
+ 
++#ifdef CONFIG_X86_64
++#define CHACHA_STATE_WORDS	((CHACHA_BLOCK_SIZE + 12) / sizeof(u32))
++#else
++#define CHACHA_STATE_WORDS	(CHACHA_BLOCK_SIZE / sizeof(u32))
++#endif
++
+ /* 192-bit nonce, then 64-bit stream position */
+ #define XCHACHA_IV_SIZE		32
+