ARM: mm: Introduce virt_to_idmap() with an arch hook

On some PAE systems (e.g. TI Keystone), memory is above the
32-bit addressable limit, and the interconnect provides an
aliased view of parts of physical memory in the 32-bit addressable
space.  This alias is strictly for boot time usage, and is not
otherwise usable because of coherency limitations. On such systems,
the idmap mechanism needs to take this aliased mapping into account.

This patch introduces virt_to_idmap() and a arch function pointer which
can be populated by platform which needs it. Also populate necessary
idmap spots with now available virt_to_idmap(). Avoided #ifdef approach
to be compatible with multi-platform builds.

Most architecture won't touch it and in that case virt_to_idmap()
fall-back to existing virt_to_phys() macro.

Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
(cherry picked from commit 4dc9a81715973cb137a14399420bb35b0ed7d6ef)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 57870ab313c52cd103b327363b0191e76efad9f6..21b458e6b0b8690bdd54fca1234b5173f0f4af98 100644 (file)
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -157,6 +157,7 @@
  */
 #define __PV_BITS_31_24        0x81000000
 
+extern phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
 extern unsigned long __pv_phys_offset;
 #define PHYS_OFFSET __pv_phys_offset
 
@@ -232,6 +233,21 @@ static inline void *phys_to_virt(phys_addr_t x)
 #define __va(x)                        ((void *)__phys_to_virt((unsigned long)(x)))
 #define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)
 
+/*
+ * These are for systems that have a hardware interconnect supported alias of
+ * physical memory for idmap purposes.  Most cases should leave these
+ * untouched.
+ */
+static inline phys_addr_t __virt_to_idmap(unsigned long x)
+{
+       if (arch_virt_to_idmap)
+               return arch_virt_to_idmap(x);
+       else
+               return __virt_to_phys(x);
+}
+
+#define virt_to_idmap(x)       __virt_to_idmap((unsigned long)(x))
+
 /*
  * Virtual <-> DMA view memory address translations
  * Again, these are *only* valid on the kernel direct mapped RAM

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 5919eb451bb9840590091c3d26a922bd65b1d005..5a8ad2c8eda080e7b648b854af88eac2a0c67d90 100644 (file)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -87,8 +87,8 @@ 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 = virt_to_idmap(idmap_pgd);
+       secondary_data.swapper_pg_dir = virt_to_idmap(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/idmap.c b/arch/arm/mm/idmap.c
index 83cb3ac27095146f3f60c04047c6b212856a73b2..c0a1e48f67338617cb2f7aeed88f67daad97d719 100644 (file)
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -10,6 +10,7 @@
 #include <asm/system_info.h>
 
 pgd_t *idmap_pgd;
+phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
 
 #ifdef CONFIG_ARM_LPAE
 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
@@ -67,8 +68,8 @@ static void identity_mapping_add(pgd_t *pgd, const char *text_start,
        unsigned long addr, end;
        unsigned long next;
 
-       addr = virt_to_phys(text_start);
-       end = virt_to_phys(text_end);
+       addr = virt_to_idmap(text_start);
+       end = virt_to_idmap(text_end);
 
        prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;