From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.3 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 18542 invoked from network); 20 Jun 2020 01:45:09 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 20 Jun 2020 01:45:09 -0000 Received: (qmail 3551 invoked by uid 550); 20 Jun 2020 01:45:00 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 3530 invoked from network); 20 Jun 2020 01:44:59 -0000 Date: Fri, 19 Jun 2020 21:44:47 -0400 From: Rich Felker To: Robert =?utf-8?B?U2tvcGFsw61r?= Cc: "musl@lists.openwall.com" , Miroslav =?utf-8?B?TsSbbWXEjWVr?= Message-ID: <20200620014447.GQ6430@brightrain.aerifal.cx> References: <20200430235109.GJ21576@brightrain.aerifal.cx> <8c3611dcf8e2c59885fecd9ebdc70d79@codeaurora.org> <20200506005929.GG21576@brightrain.aerifal.cx> <1a0301d6458e$b4264d90$1c72e8b0$@codeaurora.org> <20200618214247.GD2048759@port70.net> <096001d64684$d322d0f0$796872d0$@codeaurora.org> <20200619224624.GO6430@brightrain.aerifal.cx> <20200620001530.GP6430@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] strtok On Sat, Jun 20, 2020 at 12:46:43AM +0000, Robert Skopalík wrote: > I wouldn't like to bother you more than neccessary, but if you don't > mind (as I hope :), I have one more question: > > Do we really need got table for a noMMU MCU? Fdpic uses it and I was > looking for the answer what is it for pretty long - no success. > Wouldn't it be enough just to keep the data segment offset in r9 and > make all the data relative to it (in compiler)? That would get rid > of the whole got table complexities. Bad idea? :) That doesn't admit shared libraries, just multiple instances of the same static-linked binary. It's not a supported ABI so you'd need to hack up a toolchain and modified musl to do it. On the other hand if you don't care about sharing text at all (might be the case if yout text is expected to be very small anyway) you can just use normal PIE binaries. Rich > -----Original Message----- > From: Rich Felker [mailto:dalias@libc.org] > Sent: Saturday, June 20, 2020 2:16 AM > To: Robert Skopalík > Cc: musl@lists.openwall.com; Miroslav Němeček > Subject: Re: [musl] strtok > > On Sat, Jun 20, 2020 at 12:03:12AM +0000, Robert Skopalík wrote: > > Hello, > > > > we are working on an OS for a STM32 MCU. We like how the reentrancy > > is solved in musl, but ... when two (or more) userspace programs > > using a strtok function are run, there might be a collision (because > > strtok uses a static var to save the pointer). We did not find any > > redirection mechanism from strtok to strtok_r. How is it meant pls? > > We do not want to force the users to write strtok_r into a > > non-threaded user program. > > > > Is there some solution to make it work right? > > > > Thank you > > If multiple programs are running, each needs its own execution context > including its own versions of all libc (and any other) global data. > Probably you should look into the ARM FDPIC ABI, which is the right > way to do this while still sharing program text for MMU-less > microcontrollers like the one you're working with. The tooling should > be mature now so that support could be added to musl, but making it > happen needs people who are interested in providing feedback and > testing. > > Rich