source: trunk/hal/generic/hal_gpt.h

Last change on this file was 686, checked in by alain, 12 months ago

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1/*
2 * hal_gpt.h - Generic Page Table API definition.
3 *
4 * Authors  Alain Greiner (2016,2017,2018,2019,2020)
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_kernel_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 architecture-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 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 currently accessed by a thread         */
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    uint32_t     pte1_wait_events;  /*! total number of pte1 wait events on this gpt   */
73    uint32_t     pte1_wait_iters;   /*! total number of iterations in all pte1 wait    */
74    uint32_t     pte2_wait_events;  /*! total number of pte2 wait events on this gpt   */
75    uint32_t     pte2_wait_iters;   /*! total number of iterations in all pte2 wait    */
76}
77gpt_t;
78
79
80/****************************************************************************************
81 * This function allocates physical memory for a local GPT,
82 * and initializes the GPT descriptor, creating an empty GPT.
83 ****************************************************************************************
84 * @ gpt     : pointer on generic page table descriptor.
85 * @ returns 0 if success / returns ENOMEM if error.
86 ***************************************************************************************/
87error_t hal_gpt_create( gpt_t * gpt );
88
89/****************************************************************************************
90 * This function releases all memory dynamically allocated for a generic page table.
91 * For a multi-levels radix tree implementation, it includes all nodes in the tree.
92 * All GPT entries are supposed to be previously unmapped.
93 ****************************************************************************************
94 * @ gpt     : pointer on generic page table descriptor.
95 ***************************************************************************************/
96void hal_gpt_destroy( gpt_t * gpt);
97
98/****************************************************************************************
99 * This blocking function atomically set the GPT_LOCKED attribute in a target PTE
100 * of a remote GPT identified by the <gpt_xp> and <vpn> arguments, after checking
101 * (in a busy waiting loop) that this attribute has been reset.
102 * It returns in the <attr> and <ppn> buffers the value of the PTE before modification.
103 * It atomically allocates memory  to register this attribute in the PTE when
104 * required by a specific GPT implementation (example : allocate a PT2 in the TSAR GPT).
105 * WARNING : Only small pages can be locked.
106 ****************************************************************************************
107 * @ gpt_xp  : [in]  extended pointer on the generic page table.
108 * @ vpn     : [in]  virtual page number of the target PTE.
109 * @ attr    : [out] local buffer for GPT attributes.
110 * @ ppn     : [out] local buffer for physical page number.
111 * @ returns 0 if success / return -1 if error (no memory or big page).
112 ***************************************************************************************/
113error_t hal_gpt_lock_pte( xptr_t     gpt_xp,
114                          vpn_t      vpn,
115                          uint32_t * attr,
116                          ppn_t    * ppn );
117
118/****************************************************************************************
119 * This function atomically reset the GPT_LOCKED attribute in a target PTE in a
120 * remote GPT identified by the <gpt_xp> and <vpn> arguments.
121 ****************************************************************************************
122 * @ gpt_xp  : pointer on the generic page table
123 * @ vpn     : virtual page number of the target PTE.
124 ***************************************************************************************/
125void hal_gpt_unlock_pte( xptr_t  gpt_xp,
126                         vpn_t   vpn );
127
128/****************************************************************************************
129 * This low level function maps a new PTE or modifies an existing PTE in a remote GPT
130 * identified by the <gpt_xp> and <vpn> arguments, as defined by <ppn> and <attr> args.
131 * This function can be used for both a small page (PTE2), and a big page (PTE1).
132 *
133 * WARNING : For a small page, it checks that the GPT_LOCKED attribute has been
134 *           previously set, to prevent concurrent mapping accesses.
135 ****************************************************************************************
136 * @ gpt_xp    : [in] extended pointer on the page table
137 * @ vpn       : [in] virtual page number
138 * @ attr      : [in] GPT attributes
139 * @ ppn       : [in] physical page number
140 ***************************************************************************************/
141void hal_gpt_set_pte( xptr_t     gpt_xp,
142                      vpn_t      vpn,
143                      uint32_t   attr,
144                      ppn_t      ppn );
145
146/****************************************************************************************
147 * This low level function unmaps and unlocks a PTE from a remote GPT identified by the
148 * <gpt_xp> and <vpn> arguments. It does NOT release the allocated physical memory.
149 * This function can be used for both a small page (PTE2), and a big page (PTE1).
150 ****************************************************************************************
151 * @ gpt_xp   : [in] extended pointer on the page table
152 * @ vpn      : [in] virtual page number.
153 ***************************************************************************************/
154void hal_gpt_reset_pte( xptr_t  gpt_xp,
155                        vpn_t   vpn );
156
157/****************************************************************************************
158 * This low level function returns in the <attr> and <ppn> arguments the current values
159 * of a PTE in a a remote GPT, identified by the <gpt> and <vpn> arguments.
160 * This function can be used for both a small page (PTE2), and a big page (PTE1).
161 ****************************************************************************************
162 * @ gpt_xp    : [in]  extended pointer on the page table.
163 * @ vpn       : [in]  virtual page number.
164 * @ attr      : [out] local buffer for generic attributes.
165 * @ ppn       : [out] local buffer for physical page number.
166 ***************************************************************************************/
167void hal_gpt_get_pte( xptr_t     gpt_xp,
168                      vpn_t      vpn,
169                      uint32_t * attr,
170                      ppn_t    * ppn );
171
172/****************************************************************************************
173 * This function is used to implement the "fork" system call: It copies a remote
174 * source PTE, identified by the <src_gpt_xp> and <src_vpn> arguments, to a local
175 * destination PTE, identified by the <dst_gpt> and <dst_vpn> arguments.
176 * It does nothing if the source PTE is not MAPPED and SMALL.
177 * It optionnally activates the "Copy on Write" mechanism: when the <cow> argument is
178 * true: the GPT_WRITABLE flag is reset, and the GPT_COW flag is set.
179 * A new second level PT2 is allocated for the destination GPT if required.
180 * It returns in the <ppn> and <mapped> arguments the PPN value for the copied PTE,
181 * and a boolean indicating if the PTE is mapped and small, and was actually copied.
182 ****************************************************************************************
183 * @ dst_gpt      : [in]  local pointer on local destination GPT.
184 * @ dst_vpn      : [in]  vpn defining the PTE in the desination GPT.
185 * @ src_gpt_xp   : [in]  extended pointer on remote source GPT.
186 * @ src_vpn      : [in]  vpn defining the PTE in the source GPT.
187 * @ cow          : [in]  set COW flag & reset WRITABLE flag if true.
188 * @ ppn          : [out] PPN value (only if mapped is true).
189 * @ mapped       : [out] true if src_gpt[vpn] actually copied to dst_gpt[vpn].
190 * @ return 0 if success / return -1 if no memory for a new PT2.
191 ***************************************************************************************/
192error_t hal_gpt_pte_copy( gpt_t    * dst_gpt,
193                          vpn_t      dst_vpn,
194                          xptr_t     src_gpt_xp,
195                          vpn_t      src_vpn,
196                          bool_t     cow,
197                          ppn_t    * ppn,
198                          bool_t   * mapped );
199
200/****************************************************************************************
201 * This function atomically set the COW flag and reset the WRITABLE flag for all PTEs
202 * of a remote GPT identified by the <gpt_xp>, <vpn_base>, and <vpn_size arguments.
203 * It does NOT require the GPT_LOCKED attribute to be set in the target PTE.
204 * It does nothing if the PTE is not MAPPED and SMALL.
205 ****************************************************************************************
206 * @ gpt_xp    : [in]  extended pointer on the remote GPT.
207 * @ vpn_base  : [in]  first virtual page.
208 * @ vpn_size  : [in]  number of pages.
209 ***************************************************************************************/
210void hal_gpt_set_cow( xptr_t  gpt_xp,
211                      vpn_t   vpn_base,
212                      vpn_t   vpn_size );
213
214/****************************************************************************************
215 * This function is used to maintain coherence amongst the multiple GPT copies.
216 * It modifies an existing entry identified by the <vpn> argument in a remote GPT
217 * identified by the <gpt_xp> argument, using remote accesses.
218 * - The MAPPED and SMALL attributes must be set, and the LOCKED attibute must be reset
219 *   in the <attr> argument.
220 * - The MAPPED and SMALL attributes must be set in the target PTE.
221 ****************************************************************************************
222 * @ gpt_xp    : [in] extended pointer on the page table
223 * @ vpn       : [in] virtual page number
224 * @ attr      : [in] generic attributes
225 * @ ppn       : [in] physical page number
226 ***************************************************************************************/
227void hal_gpt_update_pte( xptr_t     gpt_xp,
228                         vpn_t      vpn,
229                         uint32_t   attr,
230                         ppn_t      ppn );
231
232
233#endif  /* _GPT_H_ */
234
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