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/* Copyright (C) 2004 David Decotigny
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
#ifndef _SOS_PAGING_H_
#define _SOS_PAGING_H_
* @file paging.h
* MMU management routines (arch-dependent). Setup the MMU without
* identity-mapping physical<->virtual addresses over the whole
* physical address space: a single, restricted and known, area is
* identity-mapped, the remaining kernel/user space is not. To access
* and manage the MMU translation tables (PD/PT on x86), we rely on a
* particular configuration, called "mirroring", where the top-level
* translation table (PD on x86) maps itself at a known and fixed (virtual)
* address. The only assumption for this to be possible is that the
* structure of the translation table entries are compatible at the
* different levels of vadddr->paddr translation process (PDE and PTE
* on x86 are Ok). Credits go to Christophe Avoinne for that.
#include <sos/types.h>
#include <sos/errno.h>
* Basic SOS virtual memory organization
/** Frontier between kernel and user space virtual addresses */
#define SOS_PAGING_BASE_USER_ADDRESS (0x40000000) /* 1GB (must be 4MB-aligned) */
#define SOS_PAGING_USER_SPACE_SIZE (0xc0000000) /* 3GB */
/** Length of the space reserved for the mirroring in the kernel
virtual space */
#define SOS_PAGING_MIRROR_SIZE (1 << 22) /* 1 PD = 1024 Page Tables = 4MB */
/** Virtual address where the mirroring takes place */
* sos_paging_map flags
/** Usual virtual memory access rights */
#define SOS_VM_MAP_PROT_READ (1<<0)
#define SOS_VM_MAP_PROT_WRITE (1<<1)
#define SOS_VM_MAP_PROT_EXEC (1<<2) /* Not supported on IA32 */
/** Mapping a page may involve an physical page allocation (for a new
PT), hence may potentially block */
#define SOS_VM_MAP_ATOMIC (1<<31)
* Setup initial page directory structure where the kernel is
* identically-mapped, and the mirroring. This routine also
* identity-maps the BIOS and video areas, to allow some debugging
* text to be printed to the console. Finally, this routine installs
* the whole configuration into the MMU.
sos_ret_t sos_paging_subsystem_setup(sos_paddr_t identity_mapping_base,
sos_paddr_t identity_mapping_top);
* Map the given physical page at the given virtual address in the
* current address space.
* @note *IMPORTANT*: The physical page ppage_paddr *MUST* have been
* referenced by the caller through either a call to
* sos_physmem_ref_physpage_new() or sos_physmem_ref_physpage_at(). It
* would work if this were untrue, but this would be INCORRECT (it is
* expected that one is owning the page before mapping it, or
* otherwise the page could have been stolen by an interrupt or
* another thread).
* @param ppage_paddr The address of a physical page (page-aligned)
* @param vpage_vaddr The address of the virtual page (page-aligned)
* @param is_user_page TRUE when the page is available from user space
* @param flags A mask made of SOS_VM_* bits
* @note Unless the SOS_VM_MAP_ATOMIC bit is set in the flags, the
* function may potentially block, because a physical page may be
* allocated for a new PT.
sos_ret_t sos_paging_map(sos_paddr_t ppage_paddr,
sos_vaddr_t vpage_vaddr,
sos_bool_t is_user_page,
sos_ui32_t flags);
* Undo the mapping from vaddr to the underlying physical page (if any)
* @param vpage_vaddr The address of the virtual page (page-aligned)
* @return >= 0 when OK (the number of bytes of RAM unmapped), < 0 on error
sos_ret_t sos_paging_unmap(sos_vaddr_t vpage_vaddr);
* Undo the mapping from [vaddr .. vaddr + size[ to the underlying
* physical pages (if any)
* @param vpage_vaddr The address of the virtual page (page-aligned)
* @param size The size (in bytes) to unmap. MUST be page-aligned
sos_ret_t sos_paging_unmap_interval(sos_vaddr_t base_vpage_vaddr,
sos_size_t size);
* Return the page protection flags (SOS_VM_MAP_PROT_*) associated
* with the address, or SOS_VM_MAP_PROT_NONE when page is not mapped
sos_ui32_t sos_paging_get_prot(sos_vaddr_t vaddr);
* Change the page access rights
sos_ret_t sos_paging_set_prot(sos_vaddr_t vaddr,
sos_ui32_t new_prot);
* Change the access rights of the mapping from [vaddr .. vaddr +
* size[ to the underlying physical pages (if any)
* @param vpage_vaddr The address of the virtual page (page-aligned)
* @param size The size (in bytes) to unmap. MUST be page-aligned
sos_ret_t sos_paging_set_prot_of_interval(sos_vaddr_t vaddr,
sos_size_t size,
sos_ui32_t new_prot);
* Return the physical address of the given virtual address. Since page
* at physical addr 0 is not mapped, the NULL result means "page not
* mapped".
sos_paddr_t sos_paging_get_paddr(sos_vaddr_t vaddr);
* Tell whether the address is physically mapped
#define sos_paging_check_present(vaddr) \
(sos_paging_get_paddr(vaddr) != NULL)
/* *************************************************
* Functions restricted to mm_context module
* Release the references to all the referenced pages (and PT on
* x86). On x86, this applies only to the USER pages and PT.
sos_ret_t sos_paging_dispose(sos_vaddr_t vaddr_PD);
* Copy the MMU configuration related to the kernel virtual area
sos_ret_t sos_paging_copy_kernel_space(sos_vaddr_t dest_vaddr_PD,
sos_vaddr_t src_vaddr_PD);
* Retrieve the current physical address of the PD
sos_paddr_t sos_paging_get_current_PD_paddr();
* Change the current MMU configuration.
* @note DANGEROUS. Don't use it unless you know exactly what you're
* doing !
sos_ret_t sos_paging_set_current_PD_paddr(sos_paddr_t paddr_PD);
#endif /* _SOS_PAGING_H_ */