tegra124: Reserve secure RAM using MC_SECURITY_CFG{0, 1}_0

These registers can be used to prevent non-secure world from accessing a
megabyte aligned region of RAM, use them to protect the u-boot secure monitor
code.

At first I tried to do this from s_init(), however this inexplicably causes
u-boot's networking (e.g. DHCP) to fail, while networking under Linux was fine.

So instead I have added a new weak arch function protect_secure_section()
called from relocate_secure_section() and reserved the region there. This is
better overall since it defers the reservation until after the sec vs. non-sec
decision (which can be influenced by an envvar) has been made when booting the
os.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
[Jan: tiny style adjustment]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/cpu/armv7/virt-v7.c

@@ -46,6 +46,10 @@ static unsigned long get_gicd_base_address(void)
 #endif
 }
 
+/* Define a specific version of this function to enable any available
+ * hardware protections for the reserved region */
+void __weak protect_secure_section(void) {}
+
 static void relocate_secure_section(void)
 {
 #ifdef CONFIG_ARMV7_SECURE_BASE
@@ -54,6 +58,7 @@ static void relocate_secure_section(void)
 	memcpy((void *)CONFIG_ARMV7_SECURE_BASE, __secure_start, sz);
 	flush_dcache_range(CONFIG_ARMV7_SECURE_BASE,
 			   CONFIG_ARMV7_SECURE_BASE + sz + 1);
+	protect_secure_section();
 	invalidate_icache_all();
 #endif
 }

arch/arm/include/asm/system.h

@@ -77,6 +77,7 @@ void armv8_switch_to_el1(void);
 void gic_init(void);
 void gic_send_sgi(unsigned long sgino);
 void wait_for_wakeup(void);
+void protect_secure_region(void);
 void smp_kick_all_cpus(void);
 
 void flush_l3_cache(void);

arch/arm/mach-tegra/ap.c

@@ -10,6 +10,7 @@
 #include <common.h>
 #include <asm/io.h>
 #include <asm/arch/gp_padctrl.h>
+#include <asm/arch/mc.h>
 #include <asm/arch-tegra/ap.h>
 #include <asm/arch-tegra/clock.h>
 #include <asm/arch-tegra/fuse.h>
@@ -154,6 +155,20 @@ static void init_pmc_scratch(void)
 	writel(odmdata, &pmc->pmc_scratch20);
 }
 
+#ifdef CONFIG_ARMV7_SECURE_RESERVE_SIZE
+void protect_secure_section(void)
+{
+	struct mc_ctlr *mc = (struct mc_ctlr *)NV_PA_MC_BASE;
+
+	/* Must be MB aligned */
+	BUILD_BUG_ON(CONFIG_ARMV7_SECURE_BASE & 0xFFFFF);
+	BUILD_BUG_ON(CONFIG_ARMV7_SECURE_RESERVE_SIZE & 0xFFFFF);
+
+	writel(CONFIG_ARMV7_SECURE_BASE, &mc->mc_security_cfg0);
+	writel(CONFIG_ARMV7_SECURE_RESERVE_SIZE >> 20, &mc->mc_security_cfg1);
+}
+#endif
+
 void s_init(void)
 {
 	/* Init PMC scratch memory */