From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hhqwh-0003V6-HX for barebox@lists.infradead.org; Mon, 01 Jul 2019 07:41:53 +0000 Date: Mon, 1 Jul 2019 09:41:47 +0200 From: Sascha Hauer Message-ID: <20190701074147.uzvalbnop5fbqnhw@pengutronix.de> References: <20190621051507.11700-1-antonynpavlov@gmail.com> <20190626065354.26nnnj2drhntespt@pengutronix.de> <20190628113545.9e490df487bea08fcd33df2b@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190628113545.9e490df487bea08fcd33df2b@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] MIPS: reloc: make flush_cache_all() usable To: Antony Pavlov Cc: barebox@lists.infradead.org, Oleksij Rempel On Fri, Jun 28, 2019 at 11:35:45AM +0300, Antony Pavlov wrote: > On Wed, 26 Jun 2019 08:53:54 +0200 > Sascha Hauer wrote: > > > Hi Antony, > > > > On Fri, Jun 21, 2019 at 08:15:07AM +0300, Antony Pavlov wrote: > > > flush_cache_all() uses 'struct cpuinfo_mips current_cpu_data' data fields. > > > These data fields are initialized in r4k_cache_init(). > > > > > > However in the current implementation the r4k_cache_init() function > > > is called __AFTER__ relocate_code(). > > > > > > Signed-off-by: Antony Pavlov > > > --- > > > arch/mips/lib/reloc.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c > > > index 14ba6167dd..6f1cd6d82f 100644 > > > --- a/arch/mips/lib/reloc.c > > > +++ b/arch/mips/lib/reloc.c > > > @@ -37,6 +37,7 @@ > > > #include > > > #include > > > #include > > > +#include > > > #include > > > #include > > > > > > @@ -157,6 +158,17 @@ void relocate_code(void *fdt, u32 fdt_size, u32 ram_size) > > > apply_reloc(type, (void *)addr, off); > > > } > > > > > > + /* clear the BSS first */ > > > + memset(__bss_start, 0x00, bss_len); > > > + > > > + cpu_probe(); > > > + > > > + if (cpu_has_4k_cache) { > > > + extern void r4k_cache_init(void); > > > + > > > + r4k_cache_init(); > > > + } > > > + > > > /* Ensure the icache is coherent */ > > > flush_cache_all(); > > > > Can we initialize one field in current_cpu_data to something nonzero so > > that it goes out of the bss? > > Or clear only current_cpu_data and keep it in bss? That would at least make it clear why this is done. That's important because otherwise some day somebody sends a patch "mips: remove duplicate clearing of bss" and I might apply it because it looks correct ;) There might be one problem with putting current_cpu_data into bss. I don't know much about MIPS booting, but in case the initial image is located in some potentially small SRAM then putting current_cpu_data into bss means that the SRAM has to be big enough for initial image and bss. > > > Another way would be to pass cpu_probe() a pointer to a struct > > cpuinfo_mips allocated on the stack and then pass it to > > flush_cache_all(). > > > > Clearing the bss twice doesn't look very nice. > > It's two diffrent bss segments: one before relocation and one after relocation. Yes, I know, otherwise you could just drop the second bss clearing. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox