sos-code-article7/sos/physmem.h

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2017-01-29 14:33:48 +01:00
/* Copyright (C) 2004 David Decotigny
Copyright (C) 2000 The KOS Team
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_PHYSMEM_H_
#define _SOS_PHYSMEM_H_
/**
* @file physmem.h
*
* Physical pages of memory
*/
#include <sos/errno.h>
#include <sos/types.h>
#include <sos/macros.h>
/** The size of a physical page (arch-dependent) */
#define SOS_PAGE_SIZE (4*1024)
/** The corresponding shift */
#define SOS_PAGE_SHIFT 12 /* 4 kB = 2^12 B */
/** The corresponding mask */
#define SOS_PAGE_MASK ((1<<12) - 1)
#define SOS_PAGE_ALIGN_INF(val) \
SOS_ALIGN_INF((val), SOS_PAGE_SIZE)
#define SOS_PAGE_ALIGN_SUP(val) \
SOS_ALIGN_SUP((val), SOS_PAGE_SIZE)
#define SOS_IS_PAGE_ALIGNED(val) \
SOS_IS_ALIGNED((val), SOS_PAGE_SIZE)
/**
* This is the reserved physical interval for the x86 video memory and
* BIOS area. In physmem.c, we have to mark this area as "nonfree" in
* order to prevent from allocating it. And in paging.c, we'd better
* map it in virtual space if we really want to be able to print to
* the screen (for debugging purpose, at least): for this, the
* simplest is to identity-map this area in virtual space (note
* however that this mapping could also be non-identical).
*/
#define BIOS_N_VIDEO_START 0xa0000
#define BIOS_N_VIDEO_END 0x100000
/**
* Initialize the physical memory subsystem, for the physical area [0,
* ram_size). This routine takes into account the BIOS and video
* areas, to prevent them from future allocations.
*
* @param ram_size The size of the RAM that will be managed by this subsystem
*
* @param kernel_core_base The lowest address for which the kernel
* assumes identity mapping (ie virtual address == physical address)
* will be stored here
*
* @param kernel_core_top The top address for which the kernel
* assumes identity mapping (ie virtual address == physical address)
* will be stored here
*/
sos_ret_t sos_physmem_subsystem_setup(sos_size_t ram_size,
/* out */sos_paddr_t *kernel_core_base,
/* out */sos_paddr_t *kernel_core_top);
/**
* Retrieve the total number of pages, and the number of free pages
*/
sos_ret_t sos_physmem_get_state(/* out */sos_count_t *total_ppages,
/* out */sos_count_t *nonfree_ppages);
/**
* Get a free page.
*
* @return The (physical) address of the (physical) page allocated, or
* NULL when none currently available.
*
* @param can_block TRUE if the function is allowed to block
* @note The page returned has a reference count equal to 1.
*/
sos_paddr_t sos_physmem_ref_physpage_new(sos_bool_t can_block);
/**
* Increment the reference count of a given physical page. Useful for
* VM code which tries to map a precise physical address.
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*
* @return TRUE when the page was previously referenced, FALSE when
* the page was previously unreferenced, <0 when the page address is
* invalid.
*/
sos_ret_t sos_physmem_ref_physpage_at(sos_paddr_t ppage_paddr);
/**
* Decrement the reference count of the given physical page. When the
* reference count of the page reaches 0, the page is marked free, ie
* is available for future sos_physmem_ref_physpage_new()
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*
* @return FALSE when the page is still referenced, TRUE when the page
* is now unreferenced, <0 when the page address is invalid
*/
sos_ret_t sos_physmem_unref_physpage(sos_paddr_t ppage_paddr);
/**
* Return the reference count of the given page
*
* @return >= 0 (the referebce count of the page) if the physical
* address is valid, or an error status
*/
sos_ret_t sos_physmem_get_physpage_refcount(sos_paddr_t ppage_paddr);
/*
* In some cases (Page Tables on x86 for example), the physical pages
* might contain a set of slots available for "allocation" (x86
* example: a PT contains a set of PTE). We provide here a set of
* functions to manage a per-page additional counter that holds this
* number of slots currently in use in the page.
*
* A newly allocated physical page has a occupation count of 0.
*
* The management of this counter is up to the subsystem that manages
* the page (mainly: paging), however a simple set of rules applies:
* - it can only be incremented/decremented if the page is referenced
* - when it reaches 0, no automatic action is undertaken
* The first rule means in particular that a page whose reference
* count reaches 0 (=> being freed) cannot have a occupation_cnt
* value > 0 ! The system will be HALTED if this ever happens
*/
/**
* Increment the occupation count of the given physical page.
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*
* @return TRUE when the occupation count was previously NON-ZERO, FALSE
* when this occupation count was 0, <0 when the page address is invalid.
*
* @note the page MUST be marked as REFERENCED by somebody !
*/
sos_ret_t sos_physmem_inc_physpage_occupation(sos_paddr_t ppage_paddr);
/**
* Decrement the occupation count of the given physical page.
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*
* @return FALSE when the occupation count is still NON-ZERO, TRUE when the
* page now is ZERO, <0 when the page address is invalid
*
* @note the page MUST be marked as REFERENCED by somebody !
*/
sos_ret_t sos_physmem_dec_physpage_occupation(sos_paddr_t ppage_paddr);
#include <sos/kmem_vmm.h>
/**
* Return the kernel memory allocation range associated with the given
* physical page, or NULL when page has no associated range
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*/
struct sos_kmem_range* sos_physmem_get_kmem_range(sos_paddr_t ppage_paddr);
/**
* Set the kernel memory allocation range associated to the given
* physical page.
*
* @param ppage_paddr Physical address of the page (MUST be page-aligned)
*
* @return error if page is invalid
*/
sos_ret_t sos_physmem_set_kmem_range(sos_paddr_t ppage_paddr,
struct sos_kmem_range *range);
#endif /* _SOS_PHYSMEM_H_ */