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001 /* Copyright (C) 2004 David Decotigny 002 003 This program is free software; you can redistribute it and/or 004 modify it under the terms of the GNU General Public License 005 as published by the Free Software Foundation; either version 2 006 of the License, or (at your option) any later version. 007 008 This program is distributed in the hope that it will be useful, 009 but WITHOUT ANY WARRANTY; without even the implied warranty of 010 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 011 GNU General Public License for more details. 012 013 You should have received a copy of the GNU General Public License 014 along with this program; if not, write to the Free Software 015 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 016 USA. 017 */ 018 #ifndef _SOS_PAGING_H_ 019 #define _SOS_PAGING_H_ 020 021 /** 022 * @file paging.h 023 * 024 * MMU management routines (arch-dependent). Setup the MMU without 025 * identity-mapping physical<->virtual addresses over the whole 026 * physical address space: a single, restricted and known, area is 027 * identity-mapped, the remaining kernel/user space is not. To access 028 * and manage the MMU translation tables (PD/PT on x86), we rely on a 029 * particular configuration, called "mirroring", where the top-level 030 * translation table (PD on x86) maps itself at a known and fixed (virtual) 031 * address. The only assumption for this to be possible is that the 032 * structure of the translation table entries are compatible at the 033 * different levels of vadddr->paddr translation process (PDE and PTE 034 * on x86 are Ok). Credits go to Christophe Avoinne for that. 035 */ 036 037 #include <sos/types.h> 038 #include <sos/errno.h> 039 040 041 /** 042 * Basic SOS virtual memory organization 043 */ 044 /** Frontier between kernel and user space virtual addresses */ 045 #define SOS_PAGING_BASE_USER_ADDRESS (0x40000000) /* 1GB */ 046 #define SOS_PAGING_TOP_USER_ADDRESS (0xFFFFFFFF) /* 4GB */ 047 048 /** Length of the space reserved for the mirroring in the kernel 049 virtual space */ 050 #define SOS_PAGING_MIRROR_SIZE (1 << 22) /* 1 PD = 1024 Page Tables = 4MB */ 051 052 /** Virtual address where the mirroring takes place */ 053 #define SOS_PAGING_MIRROR_VADDR \ 054 (SOS_PAGING_BASE_USER_ADDRESS - SOS_PAGING_MIRROR_SIZE) 055 056 057 /** 058 * sos_paging_map flags 059 */ 060 /** Usual virtual memory access rights */ 061 #define SOS_VM_MAP_PROT_NONE 0 062 #define SOS_VM_MAP_PROT_READ (1<<0) 063 #define SOS_VM_MAP_PROT_WRITE (1<<1) 064 /* EXEC not supported */ 065 066 /** Mapping a page may involve an physical page allocation (for a new 067 PT), hence may potentially block */ 068 #define SOS_VM_MAP_ATOMIC (1<<31) 069 070 071 /** 072 * Setup initial page directory structure where the kernel is 073 * identically-mapped, and the mirroring. This routine also 074 * identity-maps the BIOS and video areas, to allow some debugging 075 * text to be printed to the console. Finally, this routine installs 076 * the whole configuration into the MMU. 077 */ 078 sos_ret_t sos_paging_subsystem_setup(sos_paddr_t identity_mapping_base, 079 sos_paddr_t identity_mapping_top); 080 081 /** 082 * Map the given physical page at the given virtual address in the 083 * current address space. 084 * 085 * @note *IMPORTANT*: The physical page ppage_paddr *MUST* have been 086 * referenced by the caller through either a call to 087 * sos_physmem_ref_physpage_new() or sos_physmem_ref_physpage_at(). It 088 * would work if this were untrue, but this would be INCORRECT (it is 089 * expected that one is owning the page before mapping it, or 090 * otherwise the page could have been stolen by an interrupt or 091 * another thread). 092 * 093 * @param ppage_paddr The address of a physical page (page-aligned) 094 * @param vpage_vaddr The address of the virtual page (page-aligned) 095 * @param is_user_page TRUE when the page is available from user space 096 * @param flags A mask made of SOS_VM_* bits 097 * 098 * @note Unless the SOS_VM_MAP_ATOMIC bit is set in the flags, the 099 * function may potentially block, because a physical page may be 100 * allocated for a new PT. 101 */ 102 sos_ret_t sos_paging_map(sos_paddr_t ppage_paddr, 103 sos_vaddr_t vpage_vaddr, 104 sos_bool_t is_user_page, 105 sos_ui32_t flags); 106 107 /** 108 * Undo the mapping from vaddr to the underlying physical page (if any) 109 * @param vpage_vaddr The address of the virtual page (page-aligned) 110 */ 111 sos_ret_t sos_paging_unmap(sos_vaddr_t vpage_vaddr); 112 113 /** 114 * Return the page protection flags (SOS_VM_MAP_PROT_*) associated 115 * with the address, or SOS_VM_MAP_PROT_NONE when page is not mapped 116 */ 117 int sos_paging_get_prot(sos_vaddr_t vaddr); 118 119 /** 120 * Return the physical address of the given virtual address. Since page 121 * at physical addr 0 is not mapped, the NULL result means "page not 122 * mapped". 123 */ 124 sos_paddr_t sos_paging_get_paddr(sos_vaddr_t vaddr); 125 126 /** 127 * Tell whether the address is physically mapped 128 */ 129 #define sos_paging_check_present(vaddr) \ 130 (sos_paging_get_paddr(vaddr) != NULL) 131 132 #endif /* _SOS_PAGING_H_ */
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