/* 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
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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,
USA.
*/
#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>
/**
* sos_paging_map flags
*/
/** Usual virtual memory access rights */
#define SOS_VM_MAP_PROT_NONE 0
#define SOS_VM_MAP_PROT_READ (1<<0)
#define SOS_VM_MAP_PROT_WRITE (1<<1)
/* EXEC not supported */
/** Mapping a page may involve an physical page allocation (for a new
PT), hence may potentially block */
#define SOS_VM_MAP_ATOMIC (1<<31)
/** Virtual address where the mirroring takes place */
#define SOS_PAGING_MIRROR_VADDR 0x3fc00000 /* 1GB - 4MB */
/** 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 */
/**
* 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_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,
int flags);
/**
* Undo the mapping from vaddr to the underlying physical page (if any)
* @param vpage_vaddr The address of the virtual page (page-aligned)
*/
sos_ret_t sos_paging_unmap(sos_vaddr_t vpage_vaddr);
/**
* Return the page protection flags (SOS_VM_MAP_PROT_*) associated
* with the address, or SOS_VM_MAP_PROT_NONE when page is not mapped
*/
int sos_paging_get_prot(sos_vaddr_t vaddr);
/**
* 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)
#endif /* _SOS_PAGING_H_ */
