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authorAfzal Mohammed <afzal.mohd.ma@gmail.com>2017-02-01 13:46:36 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2017-02-28 11:06:13 +0000
commitf8300a0b5de08c09db105db3c34a2a1c618e147e (patch)
tree66ebea31f50f06f406966bb8b37e8c25bfd6cb90 /arch/arm
parentd2ca5f2491c1246adf3847101fdc538a3b89439c (diff)
downloadlinux-f8300a0b5de08c09db105db3c34a2a1c618e147e.tar.bz2
ARM: 8647/2: nommu: dynamic exception base address setting
No-MMU dynamic exception base address configuration on CP15 processors. In the case of low vectors, decision based on whether security extensions are enabled & whether remap vectors to RAM CONFIG option is selected. For no-MMU without CP15, current default value of 0x0 is retained. Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com> Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/nommu.c52
1 files changed, 50 insertions, 2 deletions
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 13a25d6282f8..3b5c7aaf9c76 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <asm/cacheflush.h>
+#include <asm/cp15.h>
#include <asm/sections.h>
#include <asm/page.h>
#include <asm/setup.h>
@@ -22,6 +23,8 @@
#include "mm.h"
+unsigned long vectors_base;
+
#ifdef CONFIG_ARM_MPU
struct mpu_rgn_info mpu_rgn_info;
@@ -278,15 +281,60 @@ static void adjust_lowmem_bounds_mpu(void) {}
static void __init mpu_setup(void) {}
#endif /* CONFIG_ARM_MPU */
+#ifdef CONFIG_CPU_CP15
+#ifdef CONFIG_CPU_HIGH_VECTOR
+static unsigned long __init setup_vectors_base(void)
+{
+ unsigned long reg = get_cr();
+
+ set_cr(reg | CR_V);
+ return 0xffff0000;
+}
+#else /* CONFIG_CPU_HIGH_VECTOR */
+/* Write exception base address to VBAR */
+static inline void set_vbar(unsigned long val)
+{
+ asm("mcr p15, 0, %0, c12, c0, 0" : : "r" (val) : "cc");
+}
+
+/*
+ * Security extensions, bits[7:4], permitted values,
+ * 0b0000 - not implemented, 0b0001/0b0010 - implemented
+ */
+static inline bool security_extensions_enabled(void)
+{
+ return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4);
+}
+
+static unsigned long __init setup_vectors_base(void)
+{
+ unsigned long base = 0, reg = get_cr();
+
+ set_cr(reg & ~CR_V);
+ if (security_extensions_enabled()) {
+ if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM))
+ base = CONFIG_DRAM_BASE;
+ set_vbar(base);
+ } else if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM)) {
+ if (CONFIG_DRAM_BASE != 0)
+ pr_err("Security extensions not enabled, vectors cannot be remapped to RAM, vectors base will be 0x00000000\n");
+ }
+
+ return base;
+}
+#endif /* CONFIG_CPU_HIGH_VECTOR */
+#endif /* CONFIG_CPU_CP15 */
+
void __init arm_mm_memblock_reserve(void)
{
#ifndef CONFIG_CPU_V7M
+ vectors_base = IS_ENABLED(CONFIG_CPU_CP15) ? setup_vectors_base() : 0;
/*
* Register the exception vector page.
* some architectures which the DRAM is the exception vector to trap,
* alloc_page breaks with error, although it is not NULL, but "0."
*/
- memblock_reserve(CONFIG_VECTORS_BASE, 2 * PAGE_SIZE);
+ memblock_reserve(vectors_base, 2 * PAGE_SIZE);
#else /* ifndef CONFIG_CPU_V7M */
/*
* There is no dedicated vector page on V7-M. So nothing needs to be
@@ -310,7 +358,7 @@ void __init adjust_lowmem_bounds(void)
*/
void __init paging_init(const struct machine_desc *mdesc)
{
- early_trap_init((void *)CONFIG_VECTORS_BASE);
+ early_trap_init((void *)vectors_base);
mpu_setup();
bootmem_init();
}