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Subject[PATCH v3 14/17] ARM: LPAE: accomodate >32-bit addresses for page table base
Date
This patch redefines the early boot time use of the R4 register to steal a few
low order bits (ARCH_PGD_SHIFT bits) on LPAE systems. This allows for up to
38-bit physical addresses.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
---
arch/arm/include/asm/memory.h | 15 +++++++++++++++
arch/arm/kernel/head.S | 10 ++++------
arch/arm/kernel/smp.c | 11 +++++++++--
arch/arm/mm/proc-v7-3level.S | 8 ++++++++
4 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 73caaeb..edf540b 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -18,6 +18,7 @@
#include <linux/types.h>
#include <linux/sizes.h>

+#include <asm/cache.h>
#include <asm/runtime-patch.h>

#ifdef CONFIG_NEED_MACH_MEMORY_H
@@ -143,6 +144,20 @@
#define page_to_phys(page) (__pfn_to_phys(page_to_pfn(page)))
#define phys_to_page(phys) (pfn_to_page(__phys_to_pfn(phys)))

+/*
+ * Minimum guaranted alignment in pgd_alloc(). The page table pointers passed
+ * around in head.S and proc-*.S are shifted by this amount, in order to
+ * leave spare high bits for systems with physical address extension. This
+ * does not fully accomodate the 40-bit addressing capability of ARM LPAE, but
+ * gives us about 38-bits or so.
+ */
+#ifdef CONFIG_ARM_LPAE
+#define ARCH_PGD_SHIFT L1_CACHE_SHIFT
+#else
+#define ARCH_PGD_SHIFT 0
+#endif
+#define ARCH_PGD_MASK ((1 << ARCH_PGD_SHIFT) - 1)
+
#ifndef __ASSEMBLY__

/*
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 61fb8df..9664db0 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -152,7 +152,7 @@ ENDPROC(stext)
*
* Returns:
* r0, r3, r5-r7 corrupted
- * r4 = physical page table address
+ * r4 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
*/
__create_page_tables:
pgtbl r4, r8 @ page table address
@@ -306,6 +306,7 @@ __create_page_tables:
#endif
#ifdef CONFIG_ARM_LPAE
sub r4, r4, #0x1000 @ point to the PGD table
+ mov r4, r4, lsr #ARCH_PGD_SHIFT
#endif
mov pc, lr
ENDPROC(__create_page_tables)
@@ -379,7 +380,7 @@ __secondary_data:
* r0 = cp#15 control register
* r1 = machine ID
* r2 = atags or dtb pointer
- * r4 = page table pointer
+ * r4 = page table (see ARCH_PGD_SHIFT in asm/memory.h)
* r9 = processor ID
* r13 = *virtual* address to jump to upon completion
*/
@@ -398,10 +399,7 @@ __enable_mmu:
#ifdef CONFIG_CPU_ICACHE_DISABLE
bic r0, r0, #CR_I
#endif
-#ifdef CONFIG_ARM_LPAE
- mov r5, #0
- mcrr p15, 0, r4, r5, c2 @ load TTBR0
-#else
+#ifndef CONFIG_ARM_LPAE
mov r5, #(domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
domain_val(DOMAIN_TABLE, DOMAIN_MANAGER) | \
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8e03567..349fdf3 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -61,6 +61,13 @@ enum ipi_msg_type {

static DECLARE_COMPLETION(cpu_running);

+static unsigned long get_arch_pgd(pgd_t *pgd)
+{
+ phys_addr_t pgdir = virt_to_phys(pgd);
+ BUG_ON(pgdir & ARCH_PGD_MASK);
+ return pgdir >> ARCH_PGD_SHIFT;
+}
+
int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
{
int ret;
@@ -70,8 +77,8 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
* its stack and the page tables.
*/
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
- secondary_data.pgdir = virt_to_phys(idmap_pgd);
- secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
+ secondary_data.pgdir = get_arch_pgd(idmap_pgd);
+ secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
__cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));

diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index 5d93f00..e920763 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S
@@ -111,6 +111,7 @@ ENDPROC(cpu_v7_set_pte_ext)
*/
.macro v7_ttb_setup, zero, ttbr0, ttbr1, tmp
ldr \tmp, =swapper_pg_dir @ swapper_pg_dir virtual address
+ mov \tmp, \tmp, lsr #ARCH_PGD_SHIFT
cmp \ttbr1, \tmp @ PHYS_OFFSET > PAGE_OFFSET? (branch below)
mrc p15, 0, \tmp, c2, c0, 2 @ TTB control register
orr \tmp, \tmp, #TTB_EAE
@@ -130,8 +131,15 @@ ENDPROC(cpu_v7_set_pte_ext)
*/
orrls \tmp, \tmp, #TTBR1_SIZE @ TTBCR.T1SZ
mcr p15, 0, \tmp, c2, c0, 2 @ TTBCR
+ mov \tmp, \ttbr1, lsr #(32 - ARCH_PGD_SHIFT) @ upper bits
+ mov \ttbr1, \ttbr1, lsl #ARCH_PGD_SHIFT @ lower bits
addls \ttbr1, \ttbr1, #TTBR1_OFFSET
mcrr p15, 1, \ttbr1, \zero, c2 @ load TTBR1
+ mov \tmp, \ttbr0, lsr #(32 - ARCH_PGD_SHIFT) @ upper bits
+ mov \ttbr0, \ttbr0, lsl #ARCH_PGD_SHIFT @ lower bits
+ mcrr p15, 0, \ttbr0, \zero, c2 @ load TTBR0
+ mcrr p15, 1, \ttbr1, \zero, c2 @ load TTBR1
+ mcrr p15, 0, \ttbr0, \zero, c2 @ load TTBR0
.endm

__CPUINIT
--
1.7.9.5


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