linux-kernel - [PATCH] lib/lzo: add unlikely hints to overrun checks

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Message-ID: <20250807114444.1341921-1-dsterba@suse.com>
Date: Thu,  7 Aug 2025 13:44:44 +0200
From: David Sterba <dsterba@...e.com>
To: linux-crypto@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	ebiggers@...nel.org,
	herbert@...dor.apana.org.au,
	David Sterba <dsterba@...e.com>
Subject: [PATCH] lib/lzo: add unlikely hints to overrun checks

The NEED_* macros do an implicit goto in case the safety bounds checks
fail. Add the unlikely hints as this is the error case and not a hot
path. The final assembly is slightly shorter and some jumps got
reordered according to the hints.

   text    data     bss     dec     hex filename
   2294      16       0    2310     906 pre/lzo1x_decompress_safe.o
   2277      16       0    2293     8f5 post/lzo1x_decompress_safe.o

   text    data     bss     dec     hex filename
   3444      48       0    3492     da4 pre/lzo1x_compress_safe.o
   3372      48       0    3420     d5c post/lzo1x_compress_safe.o

Signed-off-by: David Sterba <dsterba@...e.com>
---
 lib/lzo/lzo1x_compress.c        | 2 +-
 lib/lzo/lzo1x_decompress_safe.c | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/lzo/lzo1x_compress.c b/lib/lzo/lzo1x_compress.c
index 7b10ca86a89300..01586af2347f5e 100644
--- a/lib/lzo/lzo1x_compress.c
+++ b/lib/lzo/lzo1x_compress.c
@@ -26,7 +26,7 @@
 #define HAVE_OP(x) 1
 #endif
 
-#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
+#define NEED_OP(x) if (unlikely(!HAVE_OP(x))) goto output_overrun
 
 static noinline int
 LZO_SAFE(lzo1x_1_do_compress)(const unsigned char *in, size_t in_len,
diff --git a/lib/lzo/lzo1x_decompress_safe.c b/lib/lzo/lzo1x_decompress_safe.c
index c94f4928e1888b..318abb82c63d2c 100644
--- a/lib/lzo/lzo1x_decompress_safe.c
+++ b/lib/lzo/lzo1x_decompress_safe.c
@@ -22,9 +22,9 @@
 
 #define HAVE_IP(x)      ((size_t)(ip_end - ip) >= (size_t)(x))
 #define HAVE_OP(x)      ((size_t)(op_end - op) >= (size_t)(x))
-#define NEED_IP(x)      if (!HAVE_IP(x)) goto input_overrun
-#define NEED_OP(x)      if (!HAVE_OP(x)) goto output_overrun
-#define TEST_LB(m_pos)  if ((m_pos) < out) goto lookbehind_overrun
+#define NEED_IP(x)      if (unlikely(!HAVE_IP(x))) goto input_overrun
+#define NEED_OP(x)      if (unlikely(!HAVE_OP(x))) goto output_overrun
+#define TEST_LB(m_pos)  if (unlikely((m_pos) < out)) goto lookbehind_overrun
 
 /* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
  * count without overflowing an integer. The multiply will overflow when
-- 
2.50.1