From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 558638F57 for ; Sun, 16 Jul 2023 20:51:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA65DC433C7; Sun, 16 Jul 2023 20:51:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689540700; bh=RMp4xByG4ffeO0OOKmDWbpxiTLqmBseqZwL54lV+3dg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZnGvThgVifB98X5MJKn2d1O7l2l/rsaCjjWTiBz+I3YS4Nyh/lrP3HPbYyTl6nIeZ IHIUAKBknKxaX8vwi2j6tu6hXOVSSZO+8ZqcRwXEay07FZ7r6QchV335bmhvGnlzdT PW51m9iU1UAXKi3OFJQo5ewz28xSFCTyGmqzqNTw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Guenter Roeck , Yury Norov , Andy Shevchenko , Alexander Lobakin , Sasha Levin Subject: [PATCH 6.1 456/591] lib/bitmap: drop optimization of bitmap_{from,to}_arr64 Date: Sun, 16 Jul 2023 21:49:55 +0200 Message-ID: <20230716194935.703759168@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194923.861634455@linuxfoundation.org> References: <20230716194923.861634455@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Yury Norov [ Upstream commit c1d2ba10f594046831d14b03f194e8d05e78abad ] bitmap_{from,to}_arr64() optimization is overly optimistic on 32-bit LE architectures when it's wired to bitmap_copy_clear_tail(). bitmap_copy_clear_tail() takes care of unused bits in the bitmap up to the next word boundary. But on 32-bit machines when copying bits from bitmap to array of 64-bit words, it's expected that the unused part of a recipient array must be cleared up to 64-bit boundary, so the last 4 bytes may stay untouched when nbits % 64 <= 32. While the copying part of the optimization works correct, that clear-tail trick makes corresponding tests reasonably fail: test_bitmap: bitmap_to_arr64(nbits == 1): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000001) Fix it by removing bitmap_{from,to}_arr64() optimization for 32-bit LE arches. Reported-by: Guenter Roeck Link: https://lore.kernel.org/lkml/20230225184702.GA3587246@roeck-us.net/ Fixes: 0a97953fd221 ("lib: add bitmap_{from,to}_arr64") Signed-off-by: Yury Norov Tested-by: Guenter Roeck Reviewed-by: Andy Shevchenko Reviewed-by: Alexander Lobakin Signed-off-by: Sasha Levin --- include/linux/bitmap.h | 8 +++----- lib/bitmap.c | 2 +- 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index 7d6d73b781472..03644237e1efb 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -302,12 +302,10 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, #endif /* - * On 64-bit systems bitmaps are represented as u64 arrays internally. On LE32 - * machines the order of hi and lo parts of numbers match the bitmap structure. - * In both cases conversion is not needed when copying data from/to arrays of - * u64. + * On 64-bit systems bitmaps are represented as u64 arrays internally. So, + * the conversion is not needed when copying data from/to arrays of u64. */ -#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN) +#if BITS_PER_LONG == 32 void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits); void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits); #else diff --git a/lib/bitmap.c b/lib/bitmap.c index 1c81413c51f86..ddb31015e38ae 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -1495,7 +1495,7 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits) EXPORT_SYMBOL(bitmap_to_arr32); #endif -#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN) +#if BITS_PER_LONG == 32 /** * bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap * @bitmap: array of unsigned longs, the destination bitmap -- 2.39.2