linux-kernel - [PATCH] crypto: lib/blake2s - Split up test function to halve stack usage

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Date:   Sun, 11 Dec 2022 14:22:29 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     "Chen, Rong A" <rong.a.chen@...el.com>
Cc:     kernel test robot <lkp@...el.com>,
        "Jason A. Donenfeld" <zx2c4@...nel.org>,
        oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: [PATCH] crypto: lib/blake2s - Split up test function to halve stack
 usage

On Thu, Dec 08, 2022 at 02:37:45PM +0800, Chen, Rong A wrote:
>
> Thanks for the information, I checked the result of the fix commit,
> it reduced the stack frame but the warning still exists:
> 
> lib/crypto/blake2s-selftest.c:632:1: warning: the frame size of 1056 bytes
> is larger than 1024 bytes [-Wframe-larger-than=]

Sorry, I didn't realise that you could still reproduce it.  I tried
reproducing it on multiple architectures and failed (all were in
the 900 range).

Anyhow, this patch reduces it by half for me so hopefully it should
put this to rest.

---8<---
Reduce the stack usage further by splitting up the test function.

Also squash blocks and unaligned_blocks into one array.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/lib/crypto/blake2s-selftest.c b/lib/crypto/blake2s-selftest.c
index 7d77dea15587..484b89332c83 100644
--- a/lib/crypto/blake2s-selftest.c
+++ b/lib/crypto/blake2s-selftest.c
@@ -545,7 +545,7 @@ static const u8 blake2s_testvecs[][BLAKE2S_HASH_SIZE] __initconst = {
     0xd6, 0x98, 0x6b, 0x07, 0x10, 0x65, 0x52, 0x65, },
 };
 
-bool __init blake2s_selftest(void)
+static bool __init blake2s_digest_test(void)
 {
 	u8 key[BLAKE2S_KEY_SIZE];
 	u8 buf[ARRAY_SIZE(blake2s_testvecs)];
@@ -589,11 +589,20 @@ bool __init blake2s_selftest(void)
 		}
 	}
 
+	return success;
+}
+
+static bool __init blake2s_random_test(void)
+{
+	struct blake2s_state state;
+	bool success = true;
+	int i, l;
+
 	for (i = 0; i < 32; ++i) {
 		enum { TEST_ALIGNMENT = 16 };
-		u8 unaligned_block[BLAKE2S_BLOCK_SIZE + TEST_ALIGNMENT - 1]
+		u8 blocks[BLAKE2S_BLOCK_SIZE * 2 + TEST_ALIGNMENT - 1]
 					__aligned(TEST_ALIGNMENT);
-		u8 blocks[BLAKE2S_BLOCK_SIZE * 2];
+		u8 *unaligned_block = blocks + BLAKE2S_BLOCK_SIZE;
 		struct blake2s_state state1, state2;
 
 		get_random_bytes(blocks, sizeof(blocks));
@@ -630,3 +639,13 @@ bool __init blake2s_selftest(void)
 
 	return success;
 }
+
+bool __init blake2s_selftest(void)
+{
+	bool success;
+
+	success = blake2s_digest_test();
+	success &= blake2s_random_test();
+
+	return success;
+}
Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt