source: trunk/hal/generic/hal_gpt.h @ 407

Last change on this file since 407 was 407, checked in by alain, 5 years ago

First implementation of fork/exec.

File size: 10.6 KB
Line 
1/*
2 * hal_gpt.h - Generic Page Table API definition.
3 *
4 * Authors  Alain Greiner (2016)
5 *
6 * Copyright (c) UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH.
9 *
10 * ALMOS-MKH is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-MKH is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#ifndef _GPT_H_
25#define _GPT_H_
26
27#include <hal_types.h>
28
29/////////////////////////////////////////////////////////////////////////////////////////
30//           Generic Page Table Definition (implementation in hal_gpt.c)
31//
32// It is specified as a simple (one dimensional) array indexed by the VPN (vpn_t type),
33// even if implementations can use a more sophisticated organisation (two-levels or more).
34// - The number of entries (number of pages in a virtual space) is architecture
35//   dependent, and is defined as (CONFIG_USER_SPACE_SIZE / CONFIG_PPM_PAGE_SIZE).
36// - Each entry contains a Physical Page Number (ppn_t type), and a set of attributes,
37//   defined as masks on a 32 bits-vector.
38//
39// Any arch-specific implementation must implement this API.
40/////////////////////////////////////////////////////////////////////////////////////////
41
42/****  Forward declarations  ****/
43
44struct page_s;
45struct process_s;
46
47/****************************************************************************************
48 * These macros define the masks for the Generic Page Table Entry attributes.
49 ***************************************************************************************/
50
51#define GPT_MAPPED      0x0001       /*! PTE is mapped                                 */
52#define GPT_SMALL       0x0002       /*! PTE is a small page                           */
53#define GPT_READABLE    0x0004       /*! PTE is readable                               */
54#define GPT_WRITABLE    0x0008       /*! PTE is writable                               */
55#define GPT_EXECUTABLE  0x0010       /*! PTE is executable                             */
56#define GPT_CACHABLE    0x0020       /*! PTE can be cached                             */
57#define GPT_USER        0x0040       /*! PTE is user accessible                        */
58#define GPT_DIRTY       0x0080       /*! PTE has been "recently" written               */
59#define GPT_ACCESSED    0x0100       /*! PTE has been "recently" accessed              */
60#define GPT_GLOBAL      0x0200       /*! PTE is kept in TLB at context switch          */
61#define GPT_COW         0x0400       /*! PTE must be copied on write                   */
62#define GPT_SWAP        0x0800       /*! PTE swapped on disk (not implemented yet)     */
63#define GPT_LOCKED      0x1000       /*! PTE is protected against concurrent access    */
64
65/****************************************************************************************
66 * This structure defines the Generic Page Table descriptor.
67 ***************************************************************************************/
68
69typedef struct gpt_s
70{
71        void           * ptr;    /*! local pointer on GPT root                             */
72        ppn_t            ppn;    /*! PPN of GPT root                                       */
73}
74gpt_t;
75
76
77/****************************************************************************************
78 * This function allocates physical memory for first level page table (PT1),
79 * and initializes the page table descriptor.
80 ****************************************************************************************
81 * @ gpt     : pointer on generic page table descriptor.
82 * @ returns 0 if success / returns ENOMEM if error.
83 ***************************************************************************************/
84error_t hal_gpt_create( gpt_t * gpt );
85
86/****************************************************************************************
87 * This function releases all memory dynamically allocated for a generic page table.
88 * For a multi-levels radix tree implementation, it includes all nodes in the tree.
89 * If the calling thread is running in the reference cluster, it checks that user PTE
90 * entries are unmapped, and releases the mapped physical pages.
91 * The kernel pages are not released.
92 ****************************************************************************************
93 * @ gpt     : pointer on generic page table descriptor.
94 ***************************************************************************************/
95void hal_gpt_destroy( gpt_t * gpt);
96
97/****************************************************************************************
98 * This function prints on the kernel terminal the content of a generic page table.
99 ****************************************************************************************
100 * @ process : pointer on local process descriptor.
101 ***************************************************************************************/
102void hal_gpt_display( struct process_s * process );
103
104/****************************************************************************************
105 * This blocking function gets a lock on a PTE (Page Table Entry) identified
106 * by its VPN, and returns only when the PTE has been successfully locked.
107 * If the target PTE is not present, it allocates and maps a physical page.
108 * A big page cannot be locked.
109 ****************************************************************************************
110 * @ gpt     : pointer on the generic page table
111 * @ vpn     : virtual page number of the target PTE.
112 * @ returns 0 if success / return ENOMEM or EINVAL if error.
113 ***************************************************************************************/
114error_t hal_gpt_lock_pte( gpt_t * gpt,
115                          vpn_t   vpn );
116
117/****************************************************************************************
118 * This function releases the lock on a PTE identified by its VPN.
119 ****************************************************************************************
120 * @ gpt     : pointer on the generic page table
121 * @ vpn     : virtual page number of the target PTE.
122 * @ returns 0 if success / returns EINVAL if error.
123 ***************************************************************************************/
124error_t hal_gpt_unlock_pte( gpt_t * gpt,
125                            vpn_t   vpn );
126
127/****************************************************************************************
128 * This function maps a page table entry identified by its VPN, from values defined
129 * by the ppn and attr arguments. It allocates physical memory for the local generic
130 * page table itself if required.
131 ****************************************************************************************
132 * @ gpt       : [in] pointer on the page table
133 * @ vpn       : [in] virtual page number
134 * @ ppn       : [in] physical page number
135 * @ attr      : [in] generic attributes
136 * @ returns 0 if success / returns ENOMEM if error
137 ***************************************************************************************/
138error_t hal_gpt_set_pte( gpt_t    * gpt,
139                         vpn_t      vpn,
140                         ppn_t      ppn,
141                         uint32_t   attr );
142
143/****************************************************************************************
144 * This function unmaps a page table entry identified by the <vpn> argument in the
145 * local page table identified by the <gpt> argument.
146 * It does NOT release the physical memory allocated for the unmapped page.
147 ****************************************************************************************
148 * @ gpt       : [in] pointer on the local page table
149 * @ vpn       : [in] virtual page number
150 ***************************************************************************************/
151void hal_gpt_reset_pte( gpt_t * gpt,
152                        vpn_t   vpn );
153
154/****************************************************************************************
155 * This function returns in the ppn and attr arguments the value of a page table
156 * entry identified by its VPN.  It returns attr == 0 if the page is not mapped.
157 ****************************************************************************************
158 * @ gpt       : [in]  pointer on the page table
159 * @ vpn       : [in]  virtual page number
160 * @ attr      : [out] generic attributes
161 * @ ppn       : [out] physical page number
162 ***************************************************************************************/
163void hal_gpt_get_pte( gpt_t    * gpt,
164                      vpn_t      vpn,
165                      uint32_t * attr,
166                      ppn_t    * ppn );
167
168/****************************************************************************************
169 * This function is used to implement the "fork" system call: It copies all valid GPT
170 * entries for a given vseg identified by the <vpn_base> and <vpn_size> arguments,
171 * from the source <src_gpt> to the <dst_gpt>.
172 * It optionnally activates the "Copy on Write" mechanism: when the <cow> argument is
173 * true, the GPT_WRITABLE flag is reset, and the GPT_COW flag is set for each valid
174 * entry in the destination GPT (The data page will be dynamically allocated an copied
175 * when a write access is detected).
176 ****************************************************************************************
177 * @ dst_gpt   : [in]  pointer on the destination GPT.
178 * @ src_gpt   : [in]  pointer on the source GPT.
179 * @ vpn_base  : [in]  first vpn in vseg.
180 * @ vpn_size  : [in]  number of pages in vseg.
181 * @ cow       : [in]  activate the COPY-On-Write mechanism if true.
182 ***************************************************************************************/
183error_t hal_gpt_copy( gpt_t    * dst_gpt,
184                      gpt_t    * src_gpt,
185                      vpn_t      vpn_base,
186                      vpn_t      vpn_size,
187                      bool_t     cow );
188
189/****************************************************************************************
190 * This function returns GPT_COW flag for a PTE defined by <gpt> and <vpn> arguments.
191 ****************************************************************************************
192 * @ gpt       : [in]  pointer on the page table
193 * @ vpn       : [in]  virtual page number
194 * @ returns true if GPT_COW is set.
195 ***************************************************************************************/
196bool_t hal_gpt_pte_is_cow( gpt_t * gpt,
197                           vpn_t   vpn );
198
199
200#endif  /* _GPT_H_ */
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