linux-kernel - Re: [PATCH v3] serial: make uart_console_write->putchar()'s character an unsigned char

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1be133eb-bfe8-b644-6aad-00a0a606aa05@suse.cz>
Date:   Thu, 3 Mar 2022 07:32:59 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Richard Genoud <richard.genoud@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Tobias Klauser <tklauser@...tanz.ch>,
        Paul Cercueil <paul@...pouillou.net>,
        Russell King <linux@...linux.org.uk>,
        Vineet Gupta <vgupta@...nel.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Alexander Shiyan <shc_work@...l.ru>,
        Baruch Siach <baruch@...s.co.il>,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Karol Gugala <kgugala@...micro.com>,
        Mateusz Holenko <mholenko@...micro.com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Taichi Sugaya <sugaya.taichi@...ionext.com>,
        Takao Orito <orito.takao@...ionext.com>,
        Liviu Dudau <liviu.dudau@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andreas Färber <afaerber@...e.de>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang7@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        "David S. Miller" <davem@...emloft.net>,
        Peter Korsgaard <peter@...sgaard.com>,
        Michal Simek <michal.simek@...inx.com>
Subject: Re: [PATCH v3] serial: make uart_console_write->putchar()'s character
 an unsigned char

On 02. 03. 22, 8:27, Jiri Slaby wrote:
> Currently, uart_console_write->putchar's second parameter (the
> character) is of type int. It makes little sense, provided uart_console_write()
> accepts the input string as "const char *s" and passes its content -- the
> characters -- to putchar(). So switch the character's type to unsigned
> char.
> 
> We don't use char as that is signed on some platforms. That would cause
> troubles for drivers which (implicitly) cast the char to u16 when
> writing to the device. Sign extension would happen in that case and the
> value written would be completely different to the provided char. DZ is
> an example of such a driver -- on MIPS, it uses u16 for dz_out in
> dz_console_putchar().
> 
> Note we do the char -> uchar conversion implicitly in
> uart_console_write(). Provided we do not change size of the data type,
> sign extension does not happen there, so the problem is void.
> 
> This makes the types consistent and unified with the rest of the uart
> layer, which uses unsigned char in most places already. One exception is
> xmit_buf, but that is going to be converted later.

Kbuild seems to serve me this one by one. So this patch is still incomplete:
 > drivers/tty/serial/sunplus-uart.c:526:7: error: incompatible function 
pointer types passing 'void (struct uart_port *, int)' to parameter of 
type 'void (*)(struct uart_port *, unsigned char)'

regards,
-- 
js
suse labs