Patchwork [U-Boot,v3,2/2] ARM: OMAP5: redefine arm_setup_identity_mapping

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Submitter Vincent Stehlé
Date Dec. 11, 2012, 4:06 p.m.
Message ID <1355241981-13752-3-git-send-email-v-stehle@ti.com>
Download mbox | patch
Permalink /patch/205268/
State Superseded
Delegated to: Tom Rini
Headers show

Comments

Vincent Stehlé - Dec. 11, 2012, 4:06 p.m.
We introduce an OMAP5 specific version of arm_setup_identity_mapping(), which
makes the first page of the identity mapping invalid.

We want to unmap the region near address zero on HS OMAP devices, to avoid
speculative accesses. Accessing this region causes security violations, which
we want to avoid.

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>
Cc: Tom Rini <trini@ti.com>
---
Changes for v3:
  - Use definition of __arm_setup_identity_mapping() from asm/cache.h

Changes for v2:
  - Fix missing page_table argument
  - Add extern definition to fix compilation warning

 arch/arm/cpu/armv7/omap5/Makefile     |    1 +
 arch/arm/cpu/armv7/omap5/cache-cp15.c |   45 +++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 arch/arm/cpu/armv7/omap5/cache-cp15.c

Patch

diff --git a/arch/arm/cpu/armv7/omap5/Makefile b/arch/arm/cpu/armv7/omap5/Makefile
index 9b261c4..49c454c 100644
--- a/arch/arm/cpu/armv7/omap5/Makefile
+++ b/arch/arm/cpu/armv7/omap5/Makefile
@@ -29,6 +29,7 @@  COBJS	+= hwinit.o
 COBJS	+= clocks.o
 COBJS	+= emif.o
 COBJS	+= sdram.o
+COBJS	+= cache-cp15.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS) $(SOBJS))
diff --git a/arch/arm/cpu/armv7/omap5/cache-cp15.c b/arch/arm/cpu/armv7/omap5/cache-cp15.c
new file mode 100644
index 0000000..8e4388c
--- /dev/null
+++ b/arch/arm/cpu/armv7/omap5/cache-cp15.c
@@ -0,0 +1,45 @@ 
+/*
+ * (C) Copyright 2002
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * (C) Copyright 2012
+ * Vincent Stehlé, Texas Instruments, v-stehle@ti.com.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/cache.h>
+
+/* OMAP5 specific function to set up the identity mapping. */
+void arm_setup_identity_mapping(u32 *page_table)
+{
+	/*
+	 * Perform default mapping, which sets up an identity-mapping for all
+	 * 4GB, rw for everyone.
+	 */
+	__arm_setup_identity_mapping(page_table);
+
+	/*
+	 * First page (starting at 0x0) is made invalid to avoid speculative
+	 * accesses in secure rom.
+	 * TODO: use second level descriptors for finer grained mapping.
+	 */
+	page_table[0] = 0;
+}