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Mon, 09 Aug 2021 20:30:42 +0200 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1mDA2s-0005mK-1Q; Mon, 09 Aug 2021 20:30:42 +0200 Date: Mon, 9 Aug 2021 20:30:42 +0200 To: Ahmad Fatoum Cc: Rouven Czerwinski , barebox@lists.infradead.org Message-ID: <20210809183042.GF11515@pengutronix.de> References: <20210803094418.475609-1-r.czerwinski@pengutronix.de> <20210803094418.475609-4-r.czerwinski@pengutronix.de> <270994d8-2970-5095-2f82-f8cf29054629@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <270994d8-2970-5095-2f82-f8cf29054629@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 20:29:41 up 172 days, 21:53, 81 users, load average: 0.09, 0.06, 0.09 User-Agent: Mutt/1.10.1 (2018-07-13) From: Sascha Hauer X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210809_113044_050967_7CCE0033 X-CRM114-Status: GOOD ( 32.32 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list 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" X-SA-Exim-Connect-IP: 2607:7c80:54:e::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.7 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH v2 3/8] ARM: mmu: use reserve mem entries to modify maps X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) On Thu, Aug 05, 2021 at 04:06:42PM +0200, Ahmad Fatoum wrote: > On 03.08.21 11:44, Rouven Czerwinski wrote: > > Use the information from the reserved memory entries to modify the > > mapping of memory regions to mark them as uncachable and not-executable. > > This also prevents the processor from speculating into these regions, > > preventing hard to debug scenarios where boots fail for unknown reasons. > > > > Signed-off-by: Rouven Czerwinski > > --- > > arch/arm/cpu/mmu.c | 34 ++++++++++++++++++++++++++++++++-- > > 1 file changed, 32 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c > > index 6388e1bf14..73f4cf5b36 100644 > > --- a/arch/arm/cpu/mmu.c > > +++ b/arch/arm/cpu/mmu.c > > @@ -17,6 +17,7 @@ > > #include > > #include > > #include > > +#include > > > > #include "mmu.h" > > > > @@ -407,6 +408,36 @@ static void vectors_init(void) > > create_vector_table(ARM_LOW_VECTORS); > > } > > > > +static void create_sections_with_intersect(struct memory_bank *bank) > > +{ > > + struct of_reserve_map *res_map; > > + unsigned long j_end; > > + unsigned long end; > > + unsigned long j; > > + u32 pmd_flags; > > + int i; > > + > > + res_map = of_get_reserve_map(); > > + if (!res_map) > > + return; > > If there is no reserve map, you should still map the banks cached. > So this early exit is wrong. > > > + > > + end = bank->start + bank->size - 1; > > + > > + for (j = bank->start; j < end; j += PGDIR_SIZE) { > > + pmd_flags = PMD_SECT_DEF_CACHED; > > + j_end = j + PGDIR_SIZE - 1; > > + > > + for (i = 0; i < res_map->num_entries; i++) { > > + if ((BIT(i) & res_map->xn) && > > + j_end >= res_map->start[i] && > > + j_end <= res_map->end[i]) > > + pmd_flags = PMD_SECT_DEF_UNCACHED | PMD_SECT_XN; > > + } > > + > > + create_sections(ttb, j, j_end, pmd_flags); > > + } > > Do we need the nested loop? Can't we create sections cached first > and then iterate once over the reserved map, deduce the sections containing > start and end and map those uncached? Wouldn't that open a window to speculate into the areas we want to avoid speculating into in the first place? Sascha -- 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