linux/arch/arm/include/asm/memory.h
Russell King dc21af99fa ARM: P2V: introduce phys_to_virt/virt_to_phys runtime patching
This idea came from Nicolas, Eric Miao produced an initial version,
which was then rewritten into this.

Patch the physical to virtual translations at runtime.  As we modify
the code, this makes it incompatible with XIP kernels, but allows us
to achieve this with minimal loss of performance.

As many translations are of the form:

	physical = virtual + (PHYS_OFFSET - PAGE_OFFSET)
	virtual = physical - (PHYS_OFFSET - PAGE_OFFSET)

we generate an 'add' instruction for __virt_to_phys(), and a 'sub'
instruction for __phys_to_virt().  We calculate at run time (PHYS_OFFSET
- PAGE_OFFSET) by comparing the address prior to MMU initialization with
where it should be once the MMU has been initialized, and place this
constant into the above add/sub instructions.

Once we have (PHYS_OFFSET - PAGE_OFFSET), we can calculate the real
PHYS_OFFSET as PAGE_OFFSET is a build-time constant, and save this for
the C-mode PHYS_OFFSET variable definition to use.

At present, we are unable to support Realview with Sparsemem enabled
as this uses a complex mapping function, and MSM as this requires a
constant which will not fit in our math instruction.

Add a module version magic string for this feature to prevent
incompatible modules being loaded.

Tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-02-17 23:27:32 +00:00

297 lines
7.8 KiB
C

/*
* arch/arm/include/asm/memory.h
*
* Copyright (C) 2000-2002 Russell King
* modification for nommu, Hyok S. Choi, 2004
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Note: this file should not be included by non-asm/.h files
*/
#ifndef __ASM_ARM_MEMORY_H
#define __ASM_ARM_MEMORY_H
#include <linux/compiler.h>
#include <linux/const.h>
#include <mach/memory.h>
#include <asm/sizes.h>
/*
* Allow for constants defined here to be used from assembly code
* by prepending the UL suffix only with actual C code compilation.
*/
#define UL(x) _AC(x, UL)
#ifdef CONFIG_MMU
/*
* PAGE_OFFSET - the virtual address of the start of the kernel image
* TASK_SIZE - the maximum size of a user space task.
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area
*/
#define PAGE_OFFSET UL(CONFIG_PAGE_OFFSET)
#define TASK_SIZE (UL(CONFIG_PAGE_OFFSET) - UL(0x01000000))
#define TASK_UNMAPPED_BASE (UL(CONFIG_PAGE_OFFSET) / 3)
/*
* The maximum size of a 26-bit user space task.
*/
#define TASK_SIZE_26 UL(0x04000000)
/*
* The module space lives between the addresses given by TASK_SIZE
* and PAGE_OFFSET - it must be within 32MB of the kernel text.
*/
#ifndef CONFIG_THUMB2_KERNEL
#define MODULES_VADDR (PAGE_OFFSET - 16*1024*1024)
#else
/* smaller range for Thumb-2 symbols relocation (2^24)*/
#define MODULES_VADDR (PAGE_OFFSET - 8*1024*1024)
#endif
#if TASK_SIZE > MODULES_VADDR
#error Top of user space clashes with start of module space
#endif
/*
* The highmem pkmap virtual space shares the end of the module area.
*/
#ifdef CONFIG_HIGHMEM
#define MODULES_END (PAGE_OFFSET - PMD_SIZE)
#else
#define MODULES_END (PAGE_OFFSET)
#endif
/*
* The XIP kernel gets mapped at the bottom of the module vm area.
* Since we use sections to map it, this macro replaces the physical address
* with its virtual address while keeping offset from the base section.
*/
#define XIP_VIRT_ADDR(physaddr) (MODULES_VADDR + ((physaddr) & 0x000fffff))
/*
* Allow 16MB-aligned ioremap pages
*/
#define IOREMAP_MAX_ORDER 24
/*
* Size of DMA-consistent memory region. Must be multiple of 2M,
* between 2MB and 14MB inclusive.
*/
#ifndef CONSISTENT_DMA_SIZE
#define CONSISTENT_DMA_SIZE SZ_2M
#endif
#define CONSISTENT_END (0xffe00000UL)
#define CONSISTENT_BASE (CONSISTENT_END - CONSISTENT_DMA_SIZE)
#else /* CONFIG_MMU */
/*
* The limitation of user task size can grow up to the end of free ram region.
* It is difficult to define and perhaps will never meet the original meaning
* of this define that was meant to.
* Fortunately, there is no reference for this in noMMU mode, for now.
*/
#ifndef TASK_SIZE
#define TASK_SIZE (CONFIG_DRAM_SIZE)
#endif
#ifndef TASK_UNMAPPED_BASE
#define TASK_UNMAPPED_BASE UL(0x00000000)
#endif
#ifndef PHYS_OFFSET
#define PHYS_OFFSET UL(CONFIG_DRAM_BASE)
#endif
#ifndef END_MEM
#define END_MEM (UL(CONFIG_DRAM_BASE) + CONFIG_DRAM_SIZE)
#endif
#ifndef PAGE_OFFSET
#define PAGE_OFFSET (PHYS_OFFSET)
#endif
/*
* The module can be at any place in ram in nommu mode.
*/
#define MODULES_END (END_MEM)
#define MODULES_VADDR (PHYS_OFFSET)
#endif /* !CONFIG_MMU */
/*
* We fix the TCM memories max 32 KiB ITCM resp DTCM at these
* locations
*/
#ifdef CONFIG_HAVE_TCM
#define ITCM_OFFSET UL(0xfffe0000)
#define DTCM_OFFSET UL(0xfffe8000)
#endif
/*
* Convert a physical address to a Page Frame Number and back
*/
#define __phys_to_pfn(paddr) ((paddr) >> PAGE_SHIFT)
#define __pfn_to_phys(pfn) ((pfn) << PAGE_SHIFT)
/*
* Convert a page to/from a physical address
*/
#define page_to_phys(page) (__pfn_to_phys(page_to_pfn(page)))
#define phys_to_page(phys) (pfn_to_page(__phys_to_pfn(phys)))
#ifndef __ASSEMBLY__
/*
* Physical vs virtual RAM address space conversion. These are
* private definitions which should NOT be used outside memory.h
* files. Use virt_to_phys/phys_to_virt/__pa/__va instead.
*/
#ifndef __virt_to_phys
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
extern unsigned long __pv_phys_offset;
#define PHYS_OFFSET __pv_phys_offset
#define __pv_stub(from,to,instr) \
__asm__("@ __pv_stub\n" \
"1: " instr " %0, %1, %2\n" \
" .pushsection .pv_table,\"a\"\n" \
" .long 1b\n" \
" .popsection\n" \
: "=r" (to) \
: "r" (from), "I" (0x81000000))
static inline unsigned long __virt_to_phys(unsigned long x)
{
unsigned long t;
__pv_stub(x, t, "add");
return t;
}
static inline unsigned long __phys_to_virt(unsigned long x)
{
unsigned long t;
__pv_stub(x, t, "sub");
return t;
}
#else
#define __virt_to_phys(x) ((x) - PAGE_OFFSET + PHYS_OFFSET)
#define __phys_to_virt(x) ((x) - PHYS_OFFSET + PAGE_OFFSET)
#endif
#endif
#ifndef PHYS_OFFSET
#define PHYS_OFFSET PLAT_PHYS_OFFSET
#endif
/*
* The DMA mask corresponding to the maximum bus address allocatable
* using GFP_DMA. The default here places no restriction on DMA
* allocations. This must be the smallest DMA mask in the system,
* so a successful GFP_DMA allocation will always satisfy this.
*/
#ifndef ISA_DMA_THRESHOLD
#define ISA_DMA_THRESHOLD (0xffffffffULL)
#endif
#ifndef arch_adjust_zones
#define arch_adjust_zones(size,holes) do { } while (0)
#elif !defined(CONFIG_ZONE_DMA)
#error "custom arch_adjust_zones() requires CONFIG_ZONE_DMA"
#endif
/*
* PFNs are used to describe any physical page; this means
* PFN 0 == physical address 0.
*
* This is the PFN of the first RAM page in the kernel
* direct-mapped view. We assume this is the first page
* of RAM in the mem_map as well.
*/
#define PHYS_PFN_OFFSET (PHYS_OFFSET >> PAGE_SHIFT)
/*
* These are *only* valid on the kernel direct mapped RAM memory.
* Note: Drivers should NOT use these. They are the wrong
* translation for translating DMA addresses. Use the driver
* DMA support - see dma-mapping.h.
*/
static inline unsigned long virt_to_phys(const volatile void *x)
{
return __virt_to_phys((unsigned long)(x));
}
static inline void *phys_to_virt(unsigned long x)
{
return (void *)(__phys_to_virt((unsigned long)(x)));
}
/*
* Drivers should NOT use these either.
*/
#define __pa(x) __virt_to_phys((unsigned long)(x))
#define __va(x) ((void *)__phys_to_virt((unsigned long)(x)))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
/*
* Virtual <-> DMA view memory address translations
* Again, these are *only* valid on the kernel direct mapped RAM
* memory. Use of these is *deprecated* (and that doesn't mean
* use the __ prefixed forms instead.) See dma-mapping.h.
*/
#ifndef __virt_to_bus
#define __virt_to_bus __virt_to_phys
#define __bus_to_virt __phys_to_virt
#define __pfn_to_bus(x) __pfn_to_phys(x)
#define __bus_to_pfn(x) __phys_to_pfn(x)
#endif
static inline __deprecated unsigned long virt_to_bus(void *x)
{
return __virt_to_bus((unsigned long)x);
}
static inline __deprecated void *bus_to_virt(unsigned long x)
{
return (void *)__bus_to_virt(x);
}
/*
* Conversion between a struct page and a physical address.
*
* Note: when converting an unknown physical address to a
* struct page, the resulting pointer must be validated
* using VALID_PAGE(). It must return an invalid struct page
* for any physical address not corresponding to a system
* RAM address.
*
* page_to_pfn(page) convert a struct page * to a PFN number
* pfn_to_page(pfn) convert a _valid_ PFN number to struct page *
*
* virt_to_page(k) convert a _valid_ virtual address to struct page *
* virt_addr_valid(k) indicates whether a virtual address is valid
*/
#define ARCH_PFN_OFFSET PHYS_PFN_OFFSET
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
#define virt_addr_valid(kaddr) ((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory)
/*
* Optional coherency support. Currently used only by selected
* Intel XSC3-based systems.
*/
#ifndef arch_is_coherent
#define arch_is_coherent() 0
#endif
#endif
#include <asm-generic/memory_model.h>
#endif