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 1ED9D433A0; Sun, 16 Feb 2025 09:32:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739698329; cv=none; b=dJkNsJdbH+qOeyY9EiSlIcibK1Hx7Menguph740pNE7gdHGBE+ziGVmr401GjZrSIIywljZb5Nq1TAHSfR8b30mur++CUERaCoQjCkd8pd8aa886jBRf6ADSV0O+WaSqtKkZnHZybGnRiSEVSogpWEAtaFxETMv9hD9i4+C9nhM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739698329; c=relaxed/simple; bh=sM2HFCLqAxsh4GngDOhlxRVRtA3N/hd95Tg81RfRQFQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jhvKmTM8h2OpeMv9ebvN+I6EVaHnVreAZL1mpSACZnHwPW8T5A2nbSUPUbG3yORCLjIiLkWAJrAUp23VI+VRCZxicVZ5cenza1iFmpP97prz1OirZ7HVuaJYL12KMDhqKfH1QCLfrElpRzXZ1NXRHuMPsdFKqYKeklP6du/r2hE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VSqbu4+t; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VSqbu4+t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED22AC4CEDD; Sun, 16 Feb 2025 09:32:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739698328; bh=sM2HFCLqAxsh4GngDOhlxRVRtA3N/hd95Tg81RfRQFQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VSqbu4+tEX+C/2s1TbcFTrMIK+qL/1F+WKH2CoR28EH30Sn6dCaPq9OqX8EiHCd+Z MWLufQMzvM6Oss4aHU71MfXyhG1tG5OhtObH60+5GI9YZSXmwZUWWe4AmqL4rkBqvx qb85QA1WEXIXEBn87bKvIGV5WkoO+UF8Q2oUuTmM7s2erZND4ZYcvOz2mOlh6xc8B+ GQKD3Iq/hzrC2zV5J+3oFkYadfh7KcgciSXyAyPdg+RZQv9pKHsG8SCfwpuYiuTRVL 6PS6Yioe20W3ilHsyrawLKJ0AlYSmjXkX/9C6f6EdrlPAAOdBTYRNN9ZcYWv5WFX2A +Kw3NrbONlrRg== Date: Sun, 16 Feb 2025 09:32:04 +0000 From: Simon Horman To: David Laight Cc: Nick Child , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, haren@linux.ibm.com, ricklind@us.ibm.com, nick.child@ibm.com, jacob.e.keller@intel.com Subject: Re: [PATCH 1/3] hexdump: Implement macro for converting large buffers Message-ID: <20250216093204.GZ1615191@kernel.org> References: <20250214162436.241359-1-nnac123@linux.ibm.com> <20250214162436.241359-2-nnac123@linux.ibm.com> <20250215163612.GR1615191@kernel.org> <20250215174039.20fbbc42@pumpkin> <20250215174635.3640fb28@pumpkin> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250215174635.3640fb28@pumpkin> On Sat, Feb 15, 2025 at 05:46:35PM +0000, David Laight wrote: > On Sat, 15 Feb 2025 17:40:39 +0000 > David Laight wrote: > > > On Sat, 15 Feb 2025 16:36:12 +0000 > > Simon Horman wrote: > > > > > + David Laight > > > > > > On Fri, Feb 14, 2025 at 10:24:34AM -0600, Nick Child wrote: > > > > Define for_each_line_in_hex_dump which loops over a buffer and calls > > > > hex_dump_to_buffer for each segment in the buffer. This allows the > > > > caller to decide what to do with the resulting string and is not > > > > limited by a specific printing format like print_hex_dump. > > > > > > > > Signed-off-by: Nick Child > > > > --- > > > > include/linux/printk.h | 21 +++++++++++++++++++++ > > > > 1 file changed, 21 insertions(+) > > > > > > > > diff --git a/include/linux/printk.h b/include/linux/printk.h > > > > index 4217a9f412b2..559d4bfe0645 100644 > > > > --- a/include/linux/printk.h > > > > +++ b/include/linux/printk.h > > > > @@ -755,6 +755,27 @@ enum { > > > > extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, > > > > int groupsize, char *linebuf, size_t linebuflen, > > > > bool ascii); > > > > +/** > > > > + * for_each_line_in_hex_dump - iterate over buffer, converting into hex ASCII > > > > + * @i: offset in @buff > > > > + * @rowsize: number of bytes to print per line; must be 16 or 32 > > > > + * @linebuf: where to put the converted data > > > > + * @linebuflen: total size of @linebuf, including space for terminating NUL > > > > + * IOW >= (@rowsize * 2) + ((@rowsize - 1 / @groupsize)) + 1 > > > > + * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1) > > > > + * @buf: data blob to dump > > > > + * @len: number of bytes in the @buf > > > > + */ > > > > + #define for_each_line_in_hex_dump(i, rowsize, linebuf, linebuflen, groupsize, \ > > > > + buf, len) \ > > > > + for ((i) = 0; \ > > > > + (i) < (len) && \ > > > > + hex_dump_to_buffer((unsigned char *)(buf) + (i), \ > > > > + min((len) - (i), rowsize), \ > > > > + (rowsize), (groupsize), (linebuf), \ > > > > + (linebuflen), false); \ > > > > + (i) += (rowsize) == 16 || (rowsize) == 32 ? (rowsize) : 16 \ > > > > + ) > > > > #ifdef CONFIG_PRINTK > > > > extern void print_hex_dump(const char *level, const char *prefix_str, > > > > int prefix_type, int rowsize, int groupsize, > > > > > > Hi Nick, > > > > > > When compiling with gcc 7.5.0 (old, but still supported AFAIK) on x86_64 > > > with patch 2/3 (and 1/3) applied I see this: > > > > > > CC lib/hexdump.o > > > In file included from :0:0: > > > lib/hexdump.c: In function 'print_hex_dump': > > > ././include/linux/compiler_types.h:542:38: error: call to '__compiletime_assert_11' declared with attribute error: min((len) - (i), rowsize) signedness error > > ... > > > Highlighting the min line in the macro for context, it looks like this: > > > > > > min((len) - (i), rowsize) > > > > > > And in this case the types involved are: > > > > > > size_t len > > > int i > > > int rowsize > > > > Yep, that should fail for all versions of gcc. > > Both 'i' and 'rowsize' should be unsigned types. > > In fact all three can be 'unsigned int'. To give a bit more context, a complication changing the types is that the type of len and rowsise (but not i) is in the signature of the calling function, print_hex_dump(). And I believe that function is widely used throughout the tree. > > Thinking a bit more. > If the compiler can determine that 'rowsize >= 0' then the test will pass. > More modern compilers do better value tracking so that might be enough > to stop the compiler 'bleating'. FTR, I did not see this with GCC 14.2.0 (or clang 19.1.7).