Commit 4dc9a817 authored by Santosh Shilimkar's avatar Santosh Shilimkar
Browse files

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: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarSantosh Shilimkar <santosh.shilimkar@ti.com>
parent ca5a45c0

arch/arm/include/asm/memory.h

+16 −0
Original line number Diff line number Diff line
@@ -173,6 +173,7 @@ 
 */

#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
@@ -258,6 +259,21 @@ static inline void *phys_to_virt(phys_addr_t x) 
#define __va(x)			((void *)__phys_to_virt((phys_addr_t)(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

arch/arm/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ void __init smp_set_ops(struct smp_operations *ops) 


static unsigned long get_arch_pgd(pgd_t *pgd)

{

	phys_addr_t pgdir = virt_to_phys(pgd);

	phys_addr_t pgdir = virt_to_idmap(pgd);

	BUG_ON(pgdir & ARCH_PGD_MASK);

	return pgdir >> ARCH_PGD_SHIFT;

}

arch/arm/mm/idmap.c

+3 −2
Original line number Diff line number Diff line
@@ -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;

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