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 merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kSjiQ-0000u7-8y for barebox@lists.infradead.org; Wed, 14 Oct 2020 16:33:26 +0000 References: <20201014150824.3578133-1-m.tretter@pengutronix.de> <20201014150824.3578133-2-m.tretter@pengutronix.de> From: Ahmad Fatoum Message-ID: Date: Wed, 14 Oct 2020 18:33:25 +0200 MIME-Version: 1.0 In-Reply-To: <20201014150824.3578133-2-m.tretter@pengutronix.de> Content-Language: en-US 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 2/2] uimage: disable zero page when loading to SDRAM at address 0x0 To: Michael Tretter , barebox@lists.infradead.org On 10/14/20 5:08 PM, Michael Tretter wrote: > If the SDRAM is mapped to address 0x0 and an image should be loaded to > to the SDRAM without offset, Barebox would normally trap the access as a > null pointer. > > However, since Linux kernel commit cfa7ede20f13 ("arm64: set TEXT_OFFSET > to 0x0 in preparation for removing it entirely") no offset is the > default for arm64. Therefore, copying the image to 0x0 of the SDRAM is > necessary. > > Disable the zero page trap for copying an image to address 0x0. > > Signed-off-by: Michael Tretter > --- > common/uimage.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/common/uimage.c b/common/uimage.c > index a84b8fddc4e7..b1e9b402e98a 100644 > --- a/common/uimage.c > +++ b/common/uimage.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > static inline int uimage_is_multi_image(struct uimage_handle *handle) > { > @@ -359,7 +360,13 @@ static int uimage_sdram_flush(void *buf, unsigned int len) > } > } > > - memcpy(uimage_buf + uimage_size, buf, len); > + if (zero_page_contains((unsigned long)uimage_buf + uimage_size)) { > + zero_page_disable(); > + memcpy(uimage_buf + uimage_size, buf, len); > + zero_page_enable(); If this remains, please add a memcpy_notrap or something. > + } else { > + memcpy(uimage_buf + uimage_size, buf, len); > + } > > uimage_size += len; > > @@ -388,7 +395,14 @@ struct resource *file_to_sdram(const char *filename, unsigned long adr) > goto out; > } > > - now = read_full(fd, (void *)(res->start + ofs), BUFSIZ); > + if (zero_page_contains(res->start + ofs)) { > + zero_page_disable(); > + now = read_full(fd, (void *)(res->start + ofs), BUFSIZ); > + zero_page_enable(); And use that new memcpy_notrap here to copy from an intermediate buffer. You open quite a can of worms when you treat NULL as a valid address. Better have this contained in a single file instead of hoping the compiler doesn't do a NULL-can't-happen-here optimization in all that block/cdev/fs code that read_full may call into. > + } else { > + now = read_full(fd, (void *)(res->start + ofs), BUFSIZ); > + } > + > if (now < 0) { > release_sdram_region(res); > res = NULL; > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 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