source: trunk/hal/generic/hal_gpt.h @ 414

Last change on this file since 414 was 408, checked in by alain, 7 years ago

Fix several bugs in the fork() syscall.
File size: 13.6 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 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 map a local GPT 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 * @ attr      : [in] generic attributes
135 * @ ppn       : [in] physical page number
136 * @ returns 0 if success / returns ENOMEM if error
137 ***************************************************************************************/
138error_t hal_gpt_set_pte( gpt_t    * gpt,
139                         vpn_t      vpn,
140                         uint32_t   attr,
141                         ppn_t      ppn );
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 <attr> and <ppn> arguments the current values
156 * stored in a GPT entry, identified by the <gpt> and <vpn> arguments.
157 ****************************************************************************************
158 * @ gpt_xp    : [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 one GPT entry
170 * identified by the <vpn> argument, from a remote <src_gpt_xp> to a local <dst_gpt>.
171 * It does nothing if the source PTE is not MAPPED and SMALL.
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.
174 * A new second level PT2(s) is allocated for destination GPT if required.
175 * It returns in the <ppn> and <mapped> arguments the PPN value for the copied PTE,
176 * and a boolean indicating if the PTE is mapped and small, and was actually copied.
177 ****************************************************************************************
178 * @ dst_gpt      : [in]  local pointer on the local destination GPT.
179 * @ src_gpt_xp   : [in]  extended pointer on the remote source GPT.
180 * @ vpn_base     : [in]  vpn defining the PTE to be copied.
181 * @ cow          : [in]  activate the COPY-On-Write mechanism if true.
182 * @ ppn          : [out] PPN value (only if mapped is true).
183 * @ mapped       : [out] true if src_gpt[vpn] actually copied to dst_gpt[vpn].
184 * @ return 0 if success / return -1 if no memory for a new PT2.
185 ***************************************************************************************/
186error_t hal_gpt_pte_copy( gpt_t    * dst_gpt,
187                          xptr_t     src_gpt_xp,
188                          vpn_t      vpn,
189                          bool_t     cow,
190                          ppn_t    * ppn,
191                          bool_t   * mapped );
192
193/****************************************************************************************
194 * This function returns true if the MAPPED and SMALL flags are both set
195 * for a PTE defined by <gpt> and <vpn> arguments.
196 ****************************************************************************************
197 * @ gpt       : [in]  pointer on the page table
198 * @ vpn       : [in]  virtual page number
199 * @ returns true if MAPPED is set.
200 ***************************************************************************************/
201bool_t hal_gpt_pte_is_mapped( gpt_t * gpt,
202                              vpn_t   vpn );
203
204/****************************************************************************************
205 * This function returns true if the MAPPED, SMALL, and COW flags are all set
206 * for a PTE defined by <gpt> and <vpn> arguments.
207 ****************************************************************************************
208 * @ gpt       : [in]  pointer on the page table
209 * @ vpn       : [in]  virtual page number
210 * @ returns true if COW is set.
211 ***************************************************************************************/
212bool_t hal_gpt_pte_is_cow( gpt_t * gpt,
213                           vpn_t   vpn );
214
215/****************************************************************************************
216 * This function atomically flip the COW flag and WRITABLE flag for all PTEs
217 * of a remote GPT identified by the <gpt_xp>, <vpn_base>, and <vpn_size arguments.
218 * - it set COW and reset WRITABLE when <set_cow> argument is true and PTE is WRITABLE.
219 * - it set WRITABLE and reset COW when <set_cow> is false and PTE is COW.
220 * It does nothing if the remote PTE is not MAPPED and SMALL.
221 * It is called when a fork is executed, or when a COW must be resolved.
222 ****************************************************************************************
223 * @ set_cow   : [in]  set COW & reset WRITABLE if true / do the opposite if false.
224 * @ gpt_xp    : [in]  extended pointer on the remote GPT.
225 * @ vpn_base  : [in]  first virtual page.
226 * @ vpn_size  : [in]  number of pages.
227 ***************************************************************************************/
228void hal_gpt_flip_cow( bool_t  set_cow,
229                       xptr_t  gpt_xp,
230                       vpn_t   vpn_base,
231                       vpn_t   vpn_size );
232
233/****************************************************************************************
234 * This function is used to maintain coherence amongst the multiple GPT copies.
235 * It modifies an existing entry identified by the <vpn> argument in a remote GPT
236 * identified by the <gpt_xp> argument, using remote accesses.
237 * It cannot fail, because only MAPPED & SMALL entries are modified.
238 ****************************************************************************************
239 * @ gpt_xp    : [in] extended pointer on the page table
240 * @ vpn       : [in] virtual page number
241 * @ attr      : [in] generic attributes
242 * @ ppn       : [in] physical page number
243 ***************************************************************************************/
244void hal_gpt_update_pte( xptr_t     gpt_xp,
245                         vpn_t      vpn,
246                         uint32_t   attr,
247                         ppn_t      ppn );
248
249
250#endif  /* _GPT_H_ */
251
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